Laws of Physics

rando_ti

In the last issue of Bicycle Quarterly, we compared the performance of a 17-pound titanium racing bike and of a 26-pound steel randonneur bike. We were surprised when both bikes climbed at the same speed in a set of controlled experiments. Others shared our surprise, but added: “That cannot be true. Physics require that the heavier bike climbs slower.”

Having ridden the bikes myself, I know that their performance was evenly matched. And as a scientist, I also know that this result does not contradict the laws of physics.

Our critics assume a constant power output. If we always put out 600 Watts during these climbs, then any added weight will slow us down, all other things being equal. And an extra 9 pounds is significant enough that it should be measurable. There is little disagreement on this.

And yet the two bikes did climb at the same speed, despite their different weights. It’s clear then that our power output was not constant. On one bike, we were able to put out slightly more power than on the other – just enough extra power to equalize the weight handicap.

It should not come as a surprise that one frame performed better than another. We documented the same effect in Bicycle Quarterly’s double-blind test of frame stiffness. There, we sprinted up a hill five times, side-by-side, on two bikes. The frames had different frame tubes, but otherwise, the bikes were identical. They even weighed the same.

We switched bikes after each run. We used a PowerTap to measure power output without the rider being able to see the numbers. We found that one frame consistently was faster than the other – no matter who rode it. It wasn’t for lack of trying – as most racers know, nothing makes you ride harder than another rider pulling away.

When we downloaded the numbers from the power meter, we found that our power output was higher on the faster frame – not just a little bit, but about 5% for Mark, and 2% for me. And these were relatively similar frames, both made from lightweight, standard-diameter steel tubing.

Why did we put out more power on some frames than on others? In the above-mentioned double-blind test, we found that frame stiffness and how the frame works with our pedal strokes influences our power output. Here is how we think this works: There are different factors that limit our power output on a bike. Our hearts beat at their maximum, we are gasping for air, our legs start burning…

Our absolute maximum probably is determined by our maximum heart rate. As anybody who has trained with a heart rate monitor knows, it often is impossible to reach one’s maximum heart rate. (I used to reach ultra-high heart rates during runs that I could not achieve on my bike.)

Why can’t we always reach our maximum heart rate? The limiting factor is our muscles. If the muscles aren’t able to use the oxygen our heart pumps to them, then there is no use for our hearts to beat faster. And if one bike frame leads to more rapid muscle fatigue than the other, then our power output will be lower on that frame. (In running, I may use more muscle groups, so the cumulative oxygen use is higher, hence the higher heart rate.)

This straightforward explanation does not require invalidating the laws of physics. The simple fact is that the human body is a complex machine, and doesn’t have a constant power output.

Most cyclists have experienced inexpensive bikes that simply were “dogs” and did not perform well. We often try to explain that lack of performance with extra weight or other factors, but these bikes don’t perform well even on the flats, so one has to look for other reasons. And most of these inexpensive bikes have heavy, stiff frames that may fatigue our muscles prematurely.

Now none of the titanium bikes we tested for the Winter 2012 issue of Bicycle Quarterly were “dogs.”  They all offered awesome performance and were great fun to ride, but even near the absolute top, there were some slight, but noticeable differences in how these bikes performed for us.

Further reading:

About Jan Heine, Editor, Bicycle Quarterly

I love cycling and bicycles, especially those that take us off the beaten path. I edit Bicycle Quarterly magazine, and occasionally write for other publications. One of our companies, Bicycle Quarterly Press publishes cycling books, while Compass Bicycles Ltd. makes and distributes high-quality bicycle components for real-world riders.
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70 Responses to Laws of Physics

  1. John Doncevic says:

    Planing seems to be a factor that may help explain this result. I am not sure that a titanium frame has the same properties that “store up” the kinetic energy and then release it as a high quality, thin walled steel frame. What do you think?

    • The titanium bikes definitely did plane for us. They were awesome. If we had compared them to my beloved Alex Singer, I have no doubt they’d have been faster. Mark’s randonneur bike has been fine-tuned to our pedal strokes and riding style over years of Bicycle Quarterly research, so it’s not surprising that it works extremely well for us. There aren’t many bikes that even come close to the performance of the Lynskey Helix and the Seven Axiom SL that we tested.

  2. cbratina says:

    The PowerTap data is very intriguing, I think it would be a good idea to use a PowerTap more often in testing. It would be interesting to know what the difference between the bikes would be with a much stronger and much weaker rider. It seems like the frame flexibility may need to be tailored to a rider’s power output. Would a pro level rider be faster on the Lynskey than on Mark’s bike?

    • Those are good questions. We answered them in part: During the original “double-blind” test, I put out more power than Mark. And I did better on the stiffer frame than Mark… We put out about 600 Watts on these uphill sprints, so a stronger rider may well prefer a different frame. Also, it’s a matter of cadence – I find myself spinning less on stiffer frames to get them to flex more. So if you ride with a lower cadence, you may well prefer a stiffer frame. There are other potential variables…

      • MattS says:

        I second what Jan is saying about stiffer frames asking for a higher cadence. Look at LA’s pedalling style on his carbon Trek way back. Other riders emulated him. Some, Ulrich, for example, could not ride efficiently at the higher cadences. I suspect the frames that yield less at the bb need to get
        turned over quicker to prevent bogging down. If, like me, you are a grinder, a stiff frame will likely feel slow, unless/until you adapt your pedaling style. However, decades of grinding is not likely to be undone over night, and vice versa.

      • That matches my experience: On very stiff frames, shifting to a larger gear has me bog down, so I spin like crazy…

        On the other hand, on bikes that do plane for me, I find that a stiffer frame requires a lower cadence, perhaps to increase the force on the frame. On my Singer, which has stiffer tubing than my Herse, I spin at a lower cadence, especially when I get tired. And when I ride bikes made from thinwall, oversized tubing, which are a tad stiffer yet, I reduce my cadence even further. Even stiffer, and I just bog down (see above). It often takes me about 100 miles to adjust my cadence to a new bike, unless I’ve ridden a similar one recently.

  3. stevy says:

    When I was racing we used to say that some bikes had “a motor in the bottom bracket” or a “built in tailwind”.

    Sometimes a friend would buy a new bike from a reputable builder and not be happy. More often though, was someone selling a nearly new bike and saying it was OK or “good” and moving on to something else.

  4. MattS says:

    Can’t wait to read the test in print, Jan! Your post inspired me to write a short post on the subject: http://talltreerides.blogspot.ca/2013/02/understanding-cyborg-cyclist.html

  5. tom schibler says:

    Fascinating. Another potential factor here has to do with the “central governor theory”. Basically, perceived exertion limits output as a self-protective mechanism. So, if one bike felt easier, then your brain would allow you to push harder, generating more power, on that bike. http://www.bulletproofexec.com/3-hacking-fatigue-with-tim-noakes-plus-more-4-hour-body-fun/

  6. John Hawrylak says:

    Good explanation of why you were able to increase your power output on the steel bike and why there was no law violation.
    Based on this and your previous reports on frame planning, do you conclude the Ti frames do not plane as well as the steel frame?
    John Hawrylak
    Woodstown NJ

    • See my reply to an earlier comment… Generally speaking, I don’t think frame material is the determining factor. I used to ride an old Alan that planed wonderfully, but I have ridden other aluminum bikes that didn’t plane well. Same about carbon. Titanium to a lesser degree, because it may be hard to make it too stiff. As I said, those two bikes were wonderful, and very few steel bikes will perform that well.

  7. Bryan Willman says:

    So there are two other things to think about.

    1. Rhythm . It’s well known in lots of sports (most notably race cars of all places) that rhythm is a very big deal. So a bike’s structure might affect a particular rider’s rhythm, which I suppose might mean that ideal frame type is set by one’s body type.

    2. Training and “used-to-it-ness” – that is, it *might* be that I, who have ridden nothing but Ti bikes on road for a very long time, would now find even the nicest steel bikes not quite as fast – until I rode one quite a lot. (It was certainly true that in the days when I rode a fine steel bike I found aluminum and carbon bikes to be dogs.) This would be very difficult to double blind, since each tester would have to ride some large number of miles on each “blind” test frame.

    Finally, I am personally faster over most any coarse using my prefered shifting setup. Even if the task is to ride up a hill in a single gear. This used to befuddle me until I realized the brifters are key part of how I hang onto the bike.

    It does sometimes seem to me that discussions about “which kind of frame should I ride” are nearly as silly as when I was asked “what kind of saddle should I ride?”:

    • What we found is that the frames we used to ride were not the ones we preferred in a double-blind test. The same happened with geometries, where we found our own bikes lacking after riding “optimized” bikes.

      You are right, though, that generalized prescriptions of which frame stiffness will work best are difficult. Riding styles, pedal strokes, weights, power outputs, etc., vary a lot, and if you want to tune the frame stiffness to the rider, you need to consider those variables.

  8. Dax says:

    Jan have you calculated how much additional power it would take to neutralize the 9 lb weight advantage? I am curious why you chose to test these two bikes instead of testing bikes that are being raced on the world tour? To my knowledge there is not a single titanium bike being ridden by any team on the world tour. If you want a meaningful comparison to the state of the art why not choose among the bikes being raced at the highest level? In my mind it would be almost impossible for you to create the highly nuanced combination characteristics found in the best carbon layups using metallurgy and I think it would be interesting to try to quantify what the advantage actually is.

    • The weight difference was about 5%, once you include the rider. So the extra power required on this steep hill is probably on the order of 2-4%. It depends on the gradient, wind, etc. It’s not huge.

      Why these bikes? Well, we test any bike that shows potential. And I am very glad we did test them. They were awesome. We’ve ridden a Trek Madone, which was fine, but not nearly as nice for riders like us who are fit, but nowhere as strong as a professional racer. We’ve also tested a Calfee and a Crumpton. Those actually were nicer than the Trek, but I don’t think they were superior to the ti bikes.

      The reason that virtually all professional race sponsors have their riders use carbon bikes is pretty simple: Sponsoring a pro team makes sense for large companies that have economies of scale. If they increase their sales by 10%, their profits go up by much more, since the molds of the carbon frames are a one-time investment, no matter how many bikes you make. Titanium doesn’t scale that way, since the cost is in the labor. Making twice as many ti frames just means that your costs roughly double as well.

      • Steve Palincsar says:

        I hope you consider testing the Trek Domane. We have a couple in the club, and judging by the comments from the owners this bike seems far better suited to cracked and broken pavement on the “real world roads” we ride than the Madone. A follow-up on the Madone might be interesting, too: another club member has a new one as a replacement for the frame that was destroyed when a spoke broke on a ride and ripped the derailleur off the chainstay. He says the chainstay-mounted brakes on the new Madone are much less powerful than the Ultegra dual pivots the old frame had, and require much more lever effort to operate.

      • Dax says:

        I agree with Steve and would add that exploring the merits of the best carbon cyclo-cross frames set up as fully equipped Randonneuring bikes would be a good read.

      • Cyclocross frames are an exciting development. I qualified for PBP in 1999 riding an Alan cross frame, since my “road” bike was involved in a crash and insurance dispute. The added tire clearance definitely is a plus compared to modern racing frames. However, compared to a fully integrated randonneur bike, you’ll face two major issues:

        1. Modern cyclocross frames for the most part use mtb geometries that aren’t well-suited for front loads. So adding a handlebar bag means messing up the handling. Read here why a handlebar bag is a good idea.
        2. Cyclocross frames usually are not designed for fenders, beyond having a few eyelets. Read here what it takes to design a bike for fenders. This makes it harder to install fenders, and the clamps and brackets you need negate any weight advantage of the carbon frame.

        So you end up with a bike that doesn’t handle as well as a steel randonneur bike, weighs the same or more, and probably costs more. (For example, you’ll have to get a new front wheel with a generator hub…) Randonneuring, like cyclocross, time trialing, road racing and mountain biking, is best done on equipment that is specifically designed for the job.

  9. Dax says:

    So you feel that there is not a single pro team that would jump on the competitive advantage of a steel or titanium bike if it existed? Not one? Given the 6.9 kg weight requirement the weight disadvantage of steel would be pretty minimal…if there were climbing advantage to be had wouldn’t someone be exploiting this to achieve world wide fame and fabulous wealth? I think it would be interesting to pit those two titanium bikes vs a BMC Time Machine and a Cervelo R5 and see what the results are.

    • I don’t believe there is an inherent advantage to steel or ti, nor a disadvantage. The pro teams will use the bike that comes with the biggest offer from a sponsor, unless a component offers a huge advantage. (For example, virtually all pro teams use hand-made tires, even though they have to pay retail for them.)

      The goal of our test was not to find the fastest bike in the world. We tested two titanium bikes, and when we found them to offer awesome performance, we wondered how much we were giving up by riding our fully equipped steel randonneur bikes. To our surprise, the answer is: “Nothing.”

      • Dax says:

        It is an extreemly exciting result. Do you plan any follow up tests? If you were to design a follow up trial to confirm these results, what would it consist of?

      • Actually, this research is about 5 years old. Back then, we found that some bikes performed better than others. When we looked at the trends in the data (easy to do once you’ve ridden about 20 bikes extensively), it appeared that frame stiffness was the significant variable. So we had three frames built, two with the same “superlight” tubing we hypothesized would work best for us, one with a slightly heavier-weight tubeset. The frames were built by the same builder, on the same jig settings, painted the same color, and built up with the same components. (This was a major undertaking that cost a significant amount of money.) Then we did a double-blind test, and confirmed our hypothesis that the “superlight” frames did perform better for two of us. (The third rider was unable to tell on which of these frames he was riding.) The results were published in Bicycle Quarterly Vol. 6, No. 4.

        A follow-up was to continue the experiment, but with power measurements. This confirmed that the “superlight” frames weren’t magically faster for the same power output, but that our power output was higher on those frames. It also showed that in an all-out sprint, the rider with the higher power output could make the slightly stiffer frame work better than the rider with the slightly smaller power output. More on these experiments is here. The full report with power readings, etc., was published in Bicycle Quarterly Vol. 7, No. 4.

        We then went on to measure the stiffness of the frames and others we had tested, and found that the balance of frame stiffness mattered more than the overall stiffness. Both traditional steel racing frames and excellent modern frames like the Trek Madone have a very similar balance front-to-back. Many lesser frames don’t have it. We published that in Bicycle Quarterly Vol. 9, No. 3.

        Where to take it from there? Well, we showed that for some riders, frame stiffness matters, and that for some riders, more flexible frames with a certain, classical balance work better. We also showed that the higher the power output, the stiffer the frame should be. Considering that we put out about 600-700 Watts in these tests and liked the frames that were among the most flexible ever made, we also hypothesized that many of today’s frames are stiffer than is ideal, especially for steel frames made from oversized tubing with relatively thick walls.

        What we didn’t show is how applicable these results are to the general population. Are we freaks of nature, or is this something that benefits everybody? (The fact that two testers had the same results indicates that it’s applicable to at least a portion of the cycling population.) It would be nice to repeat this test with a bunch of cyclists, fast and slow, tall and short, etc. However, to be statistically significant, such a test would require hundreds or thousands of test subjects, dozens of frames, years of time, and that is just beyond our budget. Testing this is not as simple as a medical trial where you have patients swallow a pill or a placebo and then follow up on whether their condition improves…

        In the mean time, we are very lucky, because we now know how to make bikes that are totally optimized for us. And our new bikes are the result of that, and their performance does not disappoint. However, the fact that we, who pedal similar to generations of racers, prefer the bikes that generations of racers rode, indicates that these results are applicable to a wider population of people who pedal like those generations of racers.

  10. GuitarSlinger says:

    I also wonder how much comfort and less vibrations transmitted to the rider played a part in your experiment . Alex Moulton in the process of creating his iconic bikes proved that the vibrations transmitted to a rider in fact creates upwards of 35% extra fatigue on both the muscles and joints : thereby diminishing the capabilities of the rider especially in longer distances . Assuming Sir Alex to be correct ( and as a Moulton rider my personal experiences say he is ) its only logical then that the Randonneur bike : being both more comfortable to begin with as well as being well set up to yours and Marks riding style would at the very least equal the performance of the 17 lb Ti bike : which by its very nature is designed for performance – not comfort .

  11. Dax says:

    That’s really neat work Jan!

    • Tim Evans says:

      Yes, Jan, your reply to Dax is the best summation yet of your fame test results, and experience. Thanks for being so clear.

      You are very lucky because you know how it relates to you. How does it apply to me? Others must wonder, too. For myself, and surely many others, it is a bit of a gamble to buy a new custom bicycle. (A 650B MAP is on order.) I am not experienced enough to know what type of frame to get for my riding style. My custom 61mm top tube (oversize 8-5-8) 2008 Davidson pedals fine. It was made as a copy of my 61mm (standard [water pipe?]) 1975 Nishiki International, which I still get in rhythm with slightly easier.

      • Dax says:

        I agree. This is a fascinating topic. What I think is worth exploring is a comparison of the bikes Jan used in the trial of five years ago to the state of the art in carbon fiber today. In my mind the advantages of using carbon fiber to build frames far exceeds the weight of the material. Since some fibers can offer extremely high strength and other fibers offer extremely high stiffness an artful weave can achieve a frame that is stiff exactly where it needs to be and strong exactly here it needs to be in a much more nuanced manner that can be achieved with metallurgy. When you add this to the ease of achieving optimal tube shapes and the ease of varying the tube thickness, you really have the ability to craft a frame that has the best of all your desired characteristics. The good news for the Randoneering community is that the explosion in popularity of cyclocross has driven the development of carbon fiber frames that are easily adaptable to the preferred larger tires, fenders and luggage found on a fully equipped bike. I think that the market is moving towards a place where the choices are no longer between the open wheeled indy car and the station wagon. Carbon cyclocross bikes will soon provide a fine selection of 17 lb Lotuses with doors and head lights for Randoneers to choose from!

      • I agree that carbon fiber has a lot of potential. The biggest problem I can see is to identify what design characteristics are desirable. Some builders think stiffer is always better, but we know that this isn’t the case for many riders. (Trek once said that Lance Armstrong found one prototype Madone too stiff, so they backed off the stiffness a bit.)

        Carbon does offer more possibilities than metal tubing. Unfortunately, that also means that it’s much harder to figure out what works well, since there are more iterations to test…

        It’s sort of like suspension tuning in cars, where many large makers with multi-billion-dollar R&D budgets go to a small company in Britain (Lotus), who help them tune their suspensions. How come these makers with all their supercomputers, test tracks, etc., cannot figure it out themselves? The difference in the bike world is that the R&D budgets of most bike companies are much smaller and less impressive in real life than they are in the magazine reports…

  12. Rod Bruckdorfer says:

    My guess is over a 100 mile road race with significant climbs, the 9 lb. difference and higher rotational inertia of the randonneur bike would not fair as well against the lightweight titanium bikes or modern carbon fiber racing bikes with lightweight wheels and tubular tires.

    • That is an interesting question. One could hypothesize that since we put out more power on the randonneur bike, we’d fatigue faster, and thus would get slower at the end of a long ride. However, the data does not support this. During our last intervals, the bikes were as evenly matched as during the first. And we did get tired – we only did about 50 miles that day, but much of it was sprinting up hills.

      It appears that muscle fatigue is a bigger issue that your cardiovascular system getting tired. Thus, the bike that fatigues our muscles the least will be fastest at the end of a long ride. That matches my on-the-road experience. A bike that works really well for me comes more into its own the longer the ride is. During the Cascade 1200 last year, I was amazed at how easy it was to go fast after having been on the road for 1000 km. Those last 200 km were an amazing ride, with the bike surging over hills that I used to bog down on.

      Of course, a bike with those flex characteristics, but no fenders, lights and rack would be even (slightly) faster in a road race…

    • Greg says:

      Rod, I tend to agree (though I would add the caveat that the specific frame material is basically irrelevant, in my opinion, if the frames are designed properly, and also state that I am not a promoter of carbon-fiber or Ti bikes in general, or of modern over ‘classic’ components, so take this all with a grain of salt…). It requires more wattage to maintain the same speed(s) with the heavier bike, so over time you will do more work, i.e. burn more calories. The human body gets fatigued, which often limits performance. The key to performing well in multi-day rides is recovering well overnight. It would be very interesting to see the power data over, say, a 200-km one-day ride where the two bikes from the shorter test were used, without any switching back and forth between bikes, then somehow accurately test the riders for fatigue and overall condition after the ride. Then I guess you would want to make it a multi-day test, and somehow correct for differences between the riders’ capabilities, so it would become rather cumbersome rather quickly, I suppose?

      • Rod Bruckdorfer says:

        Greg:

        Perhaps a simpler approach is to attach power meters to each bike and have the cyclists ride together over a specified 30-40 mile course that has flat sections and climbing sections. Using software, the data from the power meters can be overlaid onto a “mapmyride” plot of the course. A comparison of the power output for each section of the route for each bike would determine which bike requires less power to negotiate the course. Unless power meters are employed in such comparison tests, any conclusion drawn is more subjective than objective. Ideally, the course should be ridden at least twice for each bike tested. Unfortunately, collecting this type of data requires a sizable investment in money and time.

        As a retired R&D chemist, I like hard data but I believe the conclusions Bicycle Quarterly draws base on hard data and subjective date are valid conclusions. After all, humans ride bikes not machines. I am certain Dr. Heine, PhD. would love to have all the testing equipment Trek, Specialize, etc. have but this type of equipment requires a hugh investment that large companies can afford and small publication cannot.

        Bicycle Quarterly is the only cycling publication I know that invests in testing bicycles and components. Further, they make their assessments/conclusions based on their findings and not whether the manufacture advertises in their publication. Their effort to understand what makes a bike fast without fatiguing the rider is commendable and adds valuable insight into bike design. Dr. Heine, PhD. refers to this characteristic as “planning.” The French called it “nervousness” and others refer to it as “lively.” Regardless, there are many frame builders utilizing the data to build frames that better matched the output of the rider, i.e. they are less fatiguing to ride and fast.

        Regarding the modern carbon fiber performance bike. I have ridden several. They are exciting to ride. Because of their lightweight wheels, “flexible” top tube, beefy down tube, chain stays, and bottom bracket they instantly respond to any change in the rider’s input into the pedals. They are beautiful pieces of engineering and technology. As a side note: I gained my experience by assembling new bikes in the Spring for my LBS. All bikes are test ridden after assembling, hence I have ridden many different types of bike ranging from the commuter type bike to high performance machine.

        Will my next bike be a carbon fiber performance bike? Mike Kone of Boulder Bicycles would answer, “No.” I take delivery of a CrMo Boulder Brevet in the spring.

      • Perhaps a simpler approach is to attach power meters to each bike and have the cyclists ride together over a specified 30-40 mile course that has flat sections and climbing sections. Using software, the data from the power meters can be overlaid onto a “mapmyride” plot of the course.

        This assumes that power output is the important variable. We already know that the rider on the heavier bike will put out more power on the uphills. Our heart rates would be higher, too. Yet at the end, the rider on the bike that “planes” better would pull away. As they have in so many of our tests.

        As so often, the easily quantifiable variable is not the important one. What we want to know is rider fatigue and the reasons for it. If we could do a muscle biopsy while riding, we might be able to measure production of lactic acid on each bike.

        Even the big bike companies do a lot of their testing on the road. That is why it is so helpful when they sponsor pro teams, because they get excellent feedback from their racers. Make three frames that are slightly different, have three racers of similar height ride them, and you’ll get some great feedback. Which isn’t very different from the testing we do at Bicycle Quarterly.

        When I was working on my Ph. D. in geology, the people in geophysics often referred to “garbage in – garbage out” models. What they meant is that even the most sophisticated model is only as good as the underlying assumptions and input data. For example, you can use finite element analysis to make a bike frame very stiff. This is great, but only if your underlying assumption, that a stiffer frame is better, is correct.

  13. Bill Gobie says:

    Jan, It’s great you noticed the “planing” phenomenon and investigated it in some depth. What you have done is tuned the frame to the cyclist’s power output characteristics. You have optimized the bicycle and rider system as a whole. (Similar to your work with wide tires, looking not just at rolling resistance losses in the tires but also taking into account vibrational losses in the rider’s body.) I only wish you had used a term already in use in engineering practice such as tuning or impedance matching.

    Custom building an optimized frame strikes me as a hit or miss proposition. It seems to me there is another method for tuning a bicycle to a rider: Ovalized chainrings. Chainrings are traditionally circular because that shape is easy to make. There is no reason to believe circular rings’ power transfer characteristics are optimal. Indeed, there is evidence, or at least proprietary claims, that ovalized rings are superior. Rotor claims a 6% power increase. http://www.rotorbikeusa.com/science.html

    At least one company, Rotor, makes ovalized rings that can be mounted on the cranks in a variety of orientations relative to the crank arms. Their road rings can be turned in increments of five degrees. This allows one to tune the rings to one’s preferences for mashing vs. spinning. Rotor encourages owners to experiment. It seems to me such chainrings offer a scientific method for tuning bicycle performance.

    • Since we only hypothesize what is going on, I don’t want to use a term that suggests that we know what is happening. People did this before when they said that stronger tubes were stiffer – they ascribed a cause to an observation. This led to great confusion when the cause turned out to be not just incorrect, but counter the laws of physics, see this blog post.

      By using a totally descriptive term borrowed from boating, we leave the door open to identifying the underlying mechanism. Oval chainrings could be interesting. We also did an experiment with a Trek bike that featured a rear suspension, and found that with very small suspension travel, the suspension could store the energy the same way a frame can, but with the advantage that it is easily tuned.

    • Greg says:

      Bill. have you ever ridden a bike with non-round chainrings for a significant distance? It’s extremely fatiguing to the leg muscles, in my experience. I tried it for a period of time back in the late 1980s, and abandoned it.

  14. Bill Gobie says:

    Greg: Yes, I have used Rotor Q-rings on my recumbent for four years, many thousands of miles, and successfully completed brevets up to 600 km. (Had I chosen the Cascade 1000 last summer instead of the 1200 I probably could list that as a success too.) I initially got them because they had a good reputation in recumbent circles for reducing knee pain. They helped with the pain, as did some other measures. An unexpected effect of the Q-rings was they greatly improved the smoothness of my spin on the recumbent. For that reason alone I think they are a fantastic upgrade for a recumbent. Back then, Rotor did not make a granny ring, so I retained a round granny ring alongside the Q-rings. The contrast between the two types of rings was dramatic. The granny was so unpleasant I avoided using it as much as possible. A year or so ago I installed a 27T Rotor granny ring and am quite pleased with it.

    Because the 27T Q-ring replaced a 24T round ring, I was concerned whether my low gear would become too high. It did not. My impression is the effort to turn a Q-ring is similar to the effort to pedal a round ring of the same minor (shortest) diameter. This makes sense when you consider that the most difficult part of the pedal stroke is pushing the pedals past top/bottom dead center.

    Another interesting thing I have noticed about Q-rings is that at high effort I feel a springiness or rebound in my pedal stroke. It is similar to the pop you get from alpine skis in short radius turns.

    I tried my Q-rings briefly on an upright. I could tell the Q-rings felt different. I did not continue the experiment long enough to see if I could discern a performance difference. I had no pain issues to address, the test bike was undergeared, and I needed the Q-rings back on the ‘bent. I am sorry I cannot offer any guidance to riders of upright bicycles.

    I have no quantifiable proof of performance enhancement such as improved climbing speed on a set course. What I have noticed and enjoyed is increased comfort and efficiency, quantities hard to measure but very important over long distances.

    Regarding your own experience, these are not the non-circular rings of your (our) youth. I wonder if you are talking about Biopace? I have some elliptical rings from that period (Sugino?) that have very high eccentricity and cannot be turned on the spider to customize them to the rider’s preferences. I have no recollection of their pedaling characteristics. Rotor and others benefit from knowledge of biomechanics that did not exist in the ’80s.

    • Greg says:

      Yes, It was Biopace rings that I tried. Just awful-feeling…..

      • Today’s proponents of oval chainrings say that Biopace rings were all-wrong. It is interesting to note that at the time, Shimano had developed these rings after spending millions of dollars on studying pedal strokes and doing computer simulations. Clearly, the interaction of human body and bicycle is more complex than most makers want to admit.

      • Greg says:

        I always liked Sugino’s “Round-Tech” chainrings! A circle is a perfect oval….
        Sort of like the butted ‘Moron’ tubing that (was it Gary Cunningham? I forget which legendary MTBer it was) marketed. It had ‘more on the ends…’ ;-)

      • I share your preference for round chainrings, but I found the Sugino rings to be so soft that they lasted at most 5000 miles on my touring bike. When I finally located a set of 110 mm BCD Campagnolo rings, I kept them on my bike for 25,000 miles. The extra money was well-spent.

      • Greg says:

        Jan, I was joking. ‘Round Tech’ was a tongue-in-cheek thing from Sugino, basically implying that the Biopace stuff was silly….

  15. marmotte27 says:

    The big difference between bikes like the Rene Herses or other Randonneur bikes that Jan and his friends and many more are riding and the carbon fibre bikes of the big makers sported by the pro teams is not in their engeneering but in their philosopy.

    Herse and the other constructeurs and their modern counterparts look art bikes from what they are meant to be on the road, for a particular rider and his particular goal. Everything, material, geometry, components will be determined by that goal. These bikes are (nearly) one offs, as the individual needs and choices are so manyfold.

    The big manufactures want to sell large numbers of bikes to whomever and the fact that carbon bikes as Jan explains can very easily raise their profits when numbers go up plays a huge role in the use of the material today. But how do you sell big numbers of bikes to the public? By creating fashion trends. So yesterday it was stiffness, today it may be comfort and tomorrow it will be something else. This works for all kinds of bikes, as long as the public is uninformed about their real needs (it takes a long experience of cycling until you know what you really need, and then you may still not have the means to get it).

    Those manufacturers dont look at creating the best bike, they look at creating the best selling bike, and that’s a world of difference!

    • It’s actually a myth that the best bikes of old were totally customized. The tubesets were standard, the geometries rarely varied, and yet the whole worked extremely well. If you take my favorite old Herse, made in 1952, you will find a standard Reynolds 531 “5/10 mm” tubeset, a standard René Herse 650B geometry, a standard René Herse front rack, and even a standard Herse blue color.

      Take my old Singer: Same tubeset as the Herse, slightly different geometry because of the 700C wheels (but again, standard for Singer), standard Singer front rack… You neither need a completely custom bike, nor do you want one, because you’d get an unproven prototype design.

      To me, the importance lies in a different aspect: In those days, the bikes were performance tools first and foremost. Yes, beautiful lugs were important, but they weren’t of any use if the bike didn’t ride extremely well.

      Today, few steel bikes are bought for their performance. If anything, carbon and titanium bike makers care more about the performance of their bikes than many “retro” companies who make steel frames. I know that given a choice between a top-level carbon bike and a “retro” steel bike for Paris-Brest-Paris, I’d pick the carbon bike.

      • Steve Palincsar says:

        I know you’ve blogged about this very point, but believe me — most cyclists would definitely consider your new Herse a “retro” bike.

  16. David says:

    “Why did we put out more power on some frames than on others?”

    You have concluded that there is something inherent about your steel frames that allows greater power output.

    I think a more likely explanation is that you put out more power on your steel frames because you were used to riding these bikes, you felt more comfortable on them, you wanted them to succeed because they are the bikes you like. ( and let’s not get confused about “double blinding” because the test of titanium vs. steel bikes was not double blinded. )

    The important detail in your side-by-side tests of these bikes is that you have used yourselves as the riders. And you are heavily invested in preferring one type of bike over another. That is understandable because part of the enjoyment of bike riding is appreciating your bike, how it looks, its history etc.

    Another point: you state that because the titanium bike is lighter, and the bikes arrive at the top of the hill at the same time, it means you are putting out more power on the steel bike. That is of course true. But this also means that riding the steel bike for a long time would be more tiring, because you would be doing more work to get the same results, since work = power X time.

    But going a step beyond, why are you trying to compare the speed of these bikes anyway? You are treating randonneuring as a form of quasi-competitive sport, training for it, recording your times and comparing them to other people. But it isn’t really racing, is it? The real racers are busy entering open competitive events. (And on the other hand I don’t think the real racers have the same appreciation for the aesthetics and history of their bikes, either. They just use whatever works the best and discard it for a new one that is better, without the same emotional attachment as recreational riders.)

    If someone just rides their bike in the country and explores, without keeping track of their time, isn’t that real randonneuring? Even the word means to wander and explore, doesn’t it? In fact your reports that I enjoy most are the ones about your “unofficial” rides with friends, which you obviously get a great deal of enjoyment from.

    But to summarize my point: you like your traditional steel bikes, and there are a lot of great reasons for you to like them. That is why you ride just as fast on them.

    • You have concluded that there is something inherent about your steel frames that allows greater power output.

      I think you are misreading our results. There is something inherent in some frames, whether made from steel, titanium, carbon or aluminum, that makes them perform better for us. We have tested many steel bikes that offered only disappointing performance.

      I think a more likely explanation is that you put out more power on your steel frames because you were used to riding these bikes, you felt more comfortable on them, you wanted them to succeed because they are the bikes you like.

      When we did our first double-blind test, both testers’ own bikes that closely matched the “standard” bike, whereas the “superlight” bike was significantly more flexible. Yet we preferred the bike that felt different from our own. The same happened when we tested front-end geometries. It is clear that we prefer an optimized setup over a familiar one.

      In our most recent test, there were two titanium bikes. Both of us like one better than the other, from a purely aesthetic point of view. Yet in our testing, it turned out to be slightly slower…

      But this also means that riding the steel bike for a long time would be more tiring, because you would be doing more work to get the same results, since work = power X time.

      That assumes that work equals fatigue. If that was the case, then running up ten flights of stairs in 1 minute would be as tiring as walking up those flights in 10 minutes. The work performed is the same. (I am using stairs, because cycling faster, wind resistance increases, whereas wind resistance is negligible when running up stairs.)

      If someone just rides their bike in the country and explores, without keeping track of their time, isn’t that real randonneuring?

      Randonneuring as an organized sport has time limits, so you need to keep track of time. More importantly, part of the enjoyment of cycling is the enjoyment of effortless speed. Otherwise, why ride a bike? You could just walk…

      In fact your reports that I enjoy most are the ones about your “unofficial” rides with friends

      Yes, those rides are great. And you are right, we don’t keep track of time. However, we do enjoy going fast, and riding a bike that offers effortless speed is exhilarating, whether the clock is ticking or not.

    • Rod Bruckdorfer says:

      David:

      I agree with all your points except W = P X T as it relates to fatigue. Over a long period or many repeated cycles, humans do become fatigued. For our purposes, let’s use the example of walking up a flight of stairs vs. running. It’s the power output that causes fatigue in this case. The runner does the same amount of work as the walker but the runners power output is significantly higher to achieve a marked decrease in the time to complete the task. Unlike a car, we can only sustain high power outputs for short periods of time before we become fatigued. As we all know, our power output is dependent on age, conditioning and our DNA makeup.

      I agree, Bicycle Quarterly’s double blind test do not follow the definition of this type of testing. “A double-blind study is one in which neither the participants or the experimenters know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results. Double-blind studies are particularly useful for preventing bias due to demand characteristics or the placebo effect.”

      “A demand characteristic is a subtle cue that makes participants aware of what the experimenter expects to find or how participants are expected to behave. Demand characteristics can change the outcome of an experiment because participants will often alter their behavior to conform to the experimenters expectations.”

      In all fairness, in the case of a bicycle it is very difficult to disguise a bike or ride a bike with a blindfold. Perhaps the tests are not true double blind tests and the results are sometimes more qualitative than quantitative, Bicycle Quarterly’s heart and intentions are on the right track. That must be one of the reasons I renewed the gift subscription my wife gave me. Lenora and I support Bicycle Quarterly and Compass Bikes through our purchases. Bye-the-bye, if you do not have a copy of “Rene Herse, The Bikes, The Builder, The Riders” I highly recommend it.

      • I agree, Bicycle Quarterly’s double blind test do not follow the definition of this type of testing. “A double-blind study is one in which neither the participants or the experimenters know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results. Double-blind studies are particularly useful for preventing bias due to demand characteristics or the placebo effect.”

        There is some confusion here between different studies. The last bike test wasn’t blind, of course.

        We did a true double-blind study five years ago, with identical bikes, marked only with numbers under the BB. The administrator of the test then placed different-colored stem caps on the bikes for each test session, and recorded which bike was “red, pink, green.” Three riders rode the bikes during multiple sessions and recorded their impressions without talking to each other. Not even the administrator knew which bike was using which tubing. And of course, the participants didn’t know whether they were riding Bike 1, 2 or 3. A bike that had the red stem cap might have the green one the next time around.

        After the test was completed, the impressions were turned in, and the test was “unblinded.” The builder told the administrator which bike had the different tubeset. We used two bikes with identical tubing, plus the “different” one, so we had a placebo. Two of three testers could tell the bikes apart 100% of the time, and preferred the two identical bikes (with the superlight tubing) over the “different” bike (with the standard-weight tubing).

        The third rider also reported preferences, but they did not match the bikes he was riding. Basically, he could not tell the bikes apart. In this test, the bikes were quite similar, so it’s not surprising that one rider might not be as sensitive as the two others.

        In any case, that old test was a true double-blind test that met all the demands for such a study.

    • Mark Vande Kamp says:

      I care much, much more about beating Jan up the hill than about the frame material of the bike I’m on when I do it.

  17. Rod Bruckdorfer says:

    Which issue was the above test published? I would love to read about the test results from this well run test.

  18. Picko says:

    A very interesting test & result. Great that you’re taking the time and trouble to do controlled studies with bikes – shame the big companies don’t spend some of their massive incomes on objective testing rather than marketing fluff. With the powertap, you’re measuring the power at the rear hub and not necessarily the power you’re applying to the crank. Could it be that you’re not putting significantly more power out, but that the frames are transferring that power to the rear wheel with different efficiencies? Would be very interested to see a comparison of data from a powertap and SRM (or other crank-based power meter) installed on the same bike – might be able to give some insight into the effects of frame stiffness/planing and power transfer efficiency.

    • We thought about that, but it’s hard to see where the power could be lost in the stiffer frame. (Remember, the stiffer frame had the lower power output.) Also, our experience of riding the bikes shows that we simply removed a limiting factor – leg pain – and thus were able to go faster. Our heart rates definitely are higher on the bikes that “plane.”

      • marten gerritsen says:

        All powermeters use some sort of averaging and a sample frequency to come up wth a number. Could it be that the way the peaks and valleys in your power output are treated influence the results?

      • I’ve been thinking about this. However, the fact that we are going faster makes the reading of higher power output believable. If we don’t put out more power on one frame, why are we going faster?

      • bgobie says:

        The faster bike made better use of your physiological effort, perhaps. Too bad it is impractical to measure metabolic parameters on the road.

        High frequency strain-gauge metering on the cranks might show how the frame affects the pedal stroke.

        Have you considered consequences of the frame flexing? When the frame twists the wheels are no longer co-planar. Perhaps this aids balance and steering. Those actions are so instinctive one is likely unaware of how much energy they consume.

  19. picko says:

    As bgobie mentions, I think it’s likely at this level of effort that you’re using a significant amount of your total power output in your core & upper body – staying balanced, pulling on the bars etc. Wonder if the more flexible frame requires a bit less upper body power (easier to balance?? returns some elastic energy??) and so this reduced ‘power overhead’ allows you to put a greater proportion of your total power through your legs? I guess this assumes that you both had a comparable total power output for both runs (very difficult to measure – comparison of AUC for HR versus time over the course of the run as a surrogate??) and that the upper body power saving would be in the region of 12-30 Watts (the 2% and 5% increases reported)

    • I doubt that any steering of a bike requires 12-30 Watts. That is a pretty significant power output, and it would make it impossible to ride no-hands.

      I think it’s simpler than that: Every cyclist has a relatively uneven power stroke. Most of the power is put out during the downstroke. (The “round pedal stroke” is an ideal, but far off the reality.) The harder you go, the more your power spikes.

      No matter how light your bike and wheels, there is too much inertia to accelerate and decelerate 4 times a second (120 rpm). During the very brief power spike on the down stroke, a flexible frame simply stores some of the energy as frame flex and returns it during the “dead spots” (6 and 12 o’clock). A stiff frame will feel like an unyielding brick wall, unable to give. And when you push against a brick wall, you don’t do any work, but you get tired very quickly.

      This hypothesis is supported by the fact that with higher power outputs, we do better on stiffer frames. The more power you put out, the more you flex the frame. Coincidentally, during the 1960s and 1970s, many racers had a stiffer frame for mass-start races, which are won with sprints and accelerations, and a more flexible frame for time trials, which are won by constant efforts at lower power outputs. Clearly, frame flex should be optimized for your power output and pedal stroke.

      • bgobie says:

        When riding no-hands one cannot exert high power, so I do not think riding no-hands is relevant here. Upper body effort is required to counter powerful pedaling. Pushing on a pedal has to be opposed by movement of the upper body over the pedal combined with pushing down less hard on the handlebar on the same side (or even pulling down). These efforts are so automatic few riders are aware of them. Strain gauge monitoring of the handlebars could be enlightening. Go try a recumbent. Until one unlearns upright pedaling instincts and entirely calms the upper body one will wobble all over creation.

        I disagree about “too much inertia”. Newton’s laws of motion apply no matter what. A bicycle has to undergo micro accelerations and decelerations throughout the pedal stroke.

      • Why do you think that riding no-hands, one cannot exert much power? Granted, putting out 600 W would be hard, but I am confident I can climb at 300+ W without holding on to the bars. Experienced riders usually have a very light touch on the handlebars…

        You are right that there will be some micro accelerations and decelerations, but they aren’t sufficient to deal with the power spikes.

  20. picko says:

    I was thinking about the whole core and upper body, not just steering using tens of Watts. The force exerted each time you push down on the pedal acts as a lever to tip the bike to one side. That force MUST be counter-balanced, otherwise you’d fall sideways. Without further measurements it’s impossible to say what level of power this requires but it’s certainly not trivial. As you say yourself, you think you can put out only half the power when not using the bars.
    As with all ‘interesting’ results, there’s a lot of debate but a lack of data with which to objectively evaluate potential mechanisms. Which is probably what makes it so interesting in the first place. Seems like there’s plenty of fodder for further testing though and I look forward to poking around in the next can of worms you open Jan!

  21. Matt Sallman says:

    Since there are now power meter pedals, perhaps you could use both pedal and wheel meters and see if you have differences between the frames.

    • Power meters average power output over 1.2 seconds (or greater intervals), so you don’t get a fine enough resolution. At 100 rpm, you average over three power strokes…

      • Matt Sallman says:

        With that sampling frequency instantaneous differences are impossible. But might there be even subtle differences after a 20 minute climb, or a longer flat section where you regularly plane?

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