What Is a Road Bike?

In past decades, there was little doubt about what made a “road” bike: narrow tires, drop handlebars, no fenders.

Then randonneur bikes were re-introduced into cycling’s mainstream, leading to some confusion. “That is a touring bike,” said many. “It has a rack and fenders.” But the performance of the randonneur bike is the same as that of a racing bike, and far from a touring bike. Basically, the randonneur bike is a racing bike with integrated fenders, lights and a small rack. (The geometry also has been tweaked to carry the load.) If you take the meaning of “road bike” literally, a randonneur bike fits it at least as well as any other bike.

And then along came wide tires, and suddenly you have a bike like the Open U.P. (above) or my Firefly. “It has 26″/ 27.5″ wheels and fat tires. It’s a rigid mountain bike with drop bars,” opined some when they saw me on one of these bikes. But it isn’t.

Imagine replacing the wheels on these bikes with 700C and installing 28 mm tires – easy enough with disc brakes. Now everybody would accept them as “road” bikes, yet the riding position, handling and even the performance would be unchanged. In fact, I would go one step further, and call them “racing bikes”, not just “road bikes”. Let me explain what I mean by “racing bike.”

The photo above shows me during my racing days. You can’t even see the bike, but there is little doubt I am riding a racing bike, not a mountain or touring bike. You can see it from my riding position.

For me, the definition of a racing bike comes down to how the bikes feels when I ride it. This is determined by:

  • Riding position: A racing bike has a relatively low, stretched-out riding position.
  • No equipment: A racing bike doesn’t carry a load, nor does it have fenders. Why is this important? These parts actually do change how the bike feels. When you ride out of the saddle and rock the bike from side to side, extra weight makes a difference. With less weight, the bike rocks much more easily. Even lightweight fenders and an empty rack change that feel – more so when that load is placed higher.

When I conceptualized this post, I expected this list to be long, but these two points already define the racing bike for me. There are other factors that are important, but they aren’t unique to a racing bike:

  • Performance: A racing bike – in fact, any performance bike – should entice its rider to go faster. It either “planes” and gets in sync with its rider, or it’s stiff and ready to sprint forward as long as the rider stays on top of his or her pedal stroke.
  • Nimble handling: A good performance bike goes exactly where you point it. It’s stable and holds its line until you ask it to change direction. Then it assumes the new course with precision and without delay. On a racing bike, most of this is due to the rotational inertia of the wheels. Whether you use 650B wheels with ultralight carbon rims and tubeless tires (as on the Open) or 26″ wheels with a more traditional setup (like the Firefly), the rotational inertia is about the same as that of a traditional racing bike with 25 mm tires. And that, as much as anything, determines how an unloaded bike feels.

On the road, this is borne out. The Open feels like a racing bike. So does my Firefly. They sprint like racing bikes. They corner like racing bikes. The biggest difference to a racing bike with narrow tires is that these bikes feel great on all roads, not just smooth ones.

This doesn’t mean that every bike with wide tires, no fenders and drop handlebars feels like a racing bike. Even before I installed a handlebar bag, the Specialized Sequoia (above left) felt like a mountain bike. Seeing the Sequoia next to my Firefly illustrated the difference between a mountain and a road bike: a more rearward weight distribution, a (slightly) more upright riding position, and much wider handlebars. The front-end geometry is different, too, with a slacker head angle and much more trail.

Riding both bikes back-to-back on mountain bike trails drove home the point: The Firefly had to be guided rather than forced, whereas the Sequoia was easy to manhandle across the bumpy terrain. The rougher the trail got, the less the Firefly was in its element, and the more the Sequoia came into its own. On gravel and paved roads, the tables were turned, and the Firefly shone with its easy, intuitive handling. Despite being superficially similar, the two bikes couldn’t have felt more different.

If the Firefly is a road bike – despite it wide tires and 26″ wheels – then what is it when equipped with low-rider racks? And what about the Specialized Diverge, a 700C bike with medium-width tires, which we also equipped with low-rider racks (below)? 

Both bikes carried a camping load, but they didn’t feel like touring bikes. Of couse, the extra weight was noticeable, but all that weight is down low, so it doesn’t have a huge effect, even when riding out of the saddle. Even with a camping load, these bikes felt like performance road bikes.

If we try to categorize the Firefly or the Sequoia (above) in this form, what would they be? Should we make up a new category: Performance tourer? Gran Turismo? Loaded racer? It starts getting silly, but in the end, it doesn’t matter. The categories between my favorite bikes are blurring, but what they all have in common is that they are performance bikes. And that is the important thing, because it makes them great fun on the rides that I enjoy!

About Jan Heine, Editor, Bicycle Quarterly

Spirited rides that zig-zag across mountain ranges. Bicycle Quarterly magazine and its sister company, Compass Cycles, that turns our research into high-performance components for real-world riders.
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46 Responses to What Is a Road Bike?

  1. mike says:

    What bike ever makes you fast on a given purpose can be called a racebike.
    Some have kickstands mounted, because it makes them fast on section controls, some have handlebar bags, fenders, wide tires, or even suspension.

    It makes sense to categorize your performance bikes, if you have different ones for different purposes. If you do all your activities with the same multi purpose bike, you can just call it “bike” 😉

    You are right, the categories between my favourite bikes are blurring too. There is no big loss using big tires on perfect concrete, but you win much on other terrain. So just mount some wider ones to enlarge the playground for that bike.
    The same is true for fenders, racks and lights – only a bit more weight, but a lot more usability and comfort.

    But a direct compare between a clean and pure road bike with small tires and a good all terrain bike shows the different nature and feel.

    This reminds me on mountain bikers, who usually tend to be prepared for each and everything with a filled backpack. It’s a good feeling to be prepared and to be independent, but being out without any freight is nice too, sometimes 😉

    • I agree with you 100% that many bikes can be performance bikes. What struck me, however, is how little the feel of a traditional racing bike depends on its tire width. As long as you keep the rotational inertia the same, the Firefly with its 54 mm tires feels remarkably like a classic racer with 25 mm tires – at least on smooth roads.

      • Thomas Anhalt says:

        My suspicion it’s more about the overall outside diameter of the particular wheel/tire combination, and its resulting effect on trail and other “working geometry” measurements, than it is about rotational inertia differences. Have you measured and/or calculated the rotational inertia differences of the combination you’re talking about? Have you then compared those differences to the total rotational + linear inertia of the entire bike plus rider system? Just curious…

      • We did test three identical bikes, one with 700C, one with 650B, and one with 26″ wheels, each with narrow, light and wide, heavy tires. Three testers independently preferred the same setups, despite coming from different backgrounds. The preferences didn’t track the outside wheel diameter, but when we calculated the rotational inertia, we found that our testers preferred rotational inertia within a narrow range. I believe this is the reason why bicycle wheel diameters haven’t changed in over a century, despite many experiments with other wheel sizes.

        If you read Jim Papadopolos’ work on bike handling, you’ll see that this matches the physics. The rotational inertia determines the bike’s stability. The changes in trail caused by a few millimeters increase in wheel diameter are of minor importance by comparison.

        Alex Moulton also was aware of this, and he made a steel ring to fit into the rims of his small-wheeled bike to increase the rotational inertia to “normal” levels. It was never put into production, though.

      • Thomas Anhalt says:

        When you say “identical”, how do you mean? If the frames where the same and you were able to put different sized wheels/tire in them, then you were changing other factors such as the C.G. as well.

      • The frames were different to adjust for the wheel size, so the geometry, BB height, etc., were the same despite the different wheel sizes.

      • Thomas Anhalt says:

        Thanks. Are there details anywhere? I’d like to see what was “adjusted” to make the the “same”…just curious.

      • The main adjustment was the BB drop and fork offset to keep BB height and trail the same with the different-sized wheels. You’ll find all the details in BQ 31. If you’re interested in the topic, it’s a must-read! Back issues are available, or check your local library.

      • jasonmiles31 says:

        Hi Jan I don’t remember your Inertia calculations. Can you remind me where these were published?

        I am very curious how my Rat Trap pass wheel and tire combo would compare to a traditional 700x23c “racing” wheel tire combo. For me the extra comfort from the large tires is a requirement, but when I used large tires on 700c wheels the toe overlap with fenders was unacceptable for low speed riding. The switch to 26″ wheels fixed this issue and my light wheel build with Stan’s ZTR 355s saved some grams.

        It would be fun to setup a inertia test as described here: http://www.bikephysics.com/wheel.pdf

      • The test was published in BQ 31. Inertia is easy to calculate – basic physics. You’ll need to make some assumptions where the center of gravity of tires, rims and tubes is, but as long as you use the same values (relative to the bead seat diameter), your relative values will be accurate across the different wheel sizes.

      • wheelriderx says:

        The inertia argument makes a lot of sense (at least in my mind). Which issue had the results? I have seen references to your wheel size experiment before (e.g., “Wheel Size Matters” – Adventure Cycling – 2013), but the actual issue has never been cited.

      • mike says:

        Rotational inertia is one thing. There is still a difference in feel and performance (just my subjective observations) going uphill aggressively or or cornering downhill long curves at the limits. This is also part of “how a bike behaves” and has to be different on wide smooth tires since we want this extra suspension on less ideal terrain.
        Nevertheless I prefer the performance and comfort of wide tires on mixed surfaces or long tours.

      • I agree – wider tires will always offer more grip in cornering. That is why I prefer them even on smooth roads.

      • mike says:

        I have the feeling, that the flexing of wide tire slows me down in long curves. Even if the max speed can be higher due to more possible grip you may leave long and fast curves slower?! Subjective observation, of course, I cannot measure it.
        Well, that’s a very specific use case, winding downwards on perfect concrete …. The more important part probably is the way your tire (wide or small) tells you where the limit is 😉 It always takes me some kilometers to get the right feeling when switching from small to wide or vice versa.

        Same feeling climbing uphill steep roads in an aggressive manner. The flexing seems to steal performance here, subjective observation too. If the surface gets less ideal, the wide tire trumps here as well as downhill.

        And, of course, I talk about bits of performance, that get lost in the overall performance on a complete track …

      • When we measure tire performance on a velodrome, most of the measurement is in long curves, yet wider tires aren’t slower. Of course, at higher speed any flex could be more pronounced, but so far, I haven’t noticed any disadvantage when descending with riders on narrower tires or vice versa.

  2. Chris says:

    Interesting read. You guys should ask these guys (masoncycles.cc) for a “Bokeh” to review. It’d be right up your alley. Their “Resolution” is a great steel (with carbon fork) “road bike” that I ride, but the Bokeh can take different sized wheels. I’d love to hear your thoughts on that bike.

  3. Jores Juarez says:

    I remember when touring bikes were considered road bikes as well — they were designed to be ridden on roads, as opposed to being ridden in a velodrome. The term was co-opted around the late 1980s (with the rise of mountain bikes and the decline of sport touring bikes) to be synonymous with “road racing” bikes. I do not think it was an improvement in the nomenclature.

  4. Jenny says:

    The way I see it, there are walking bikes and there are running bikes, depending on which they are most designed to assist. Considerations of load and surface are orthogonal to that.

  5. Chris Pavsek says:

    Jan Heine wrote: “We did test three identical bikes, one with 700C, one with 650B, and one with 26″ wheels, each with narrow, light and wide, heavy tires. Three testers independently preferred the same setups, despite coming from different backgrounds. The preferences didn’t track the outside wheel diameter, but when we calculated the rotational inertia, we found that our testers preferred rotational inertia within a narrow range.”

    I’m curious, what was the preferred setup? And was this the setup with the lowest rotational inertia?

  6. François says:

    Do you think the diverge is currently the best option for a relatively low-cost, easy-available versatile kind of bike ? Did you have a look at the new diverge 2018 ? Do you think it goes in the right direction with respect to the 2017 version ? It seems quite hard to find an affordable and easy to obtain bike that fits what you have promulgated : wide tires, road geometry, ability to take fenders and racks at the same time… Thanks in advance for your help.

    • Conrad says:

      I’ll add my 2 cents: the Diverge has a lot of flaws for being billed as an all road adventure bike: doesn’t really have low trail geometry, no generator lights for starters. Carbon fiber, so how long will it last? For what the Diverge costs, you would be well on your way to a cost-be-damned hand built dream bike by a well regarded builder. I am in your shoes in terms of what I want in a bike and having a limited amount of money to spend. I bought a Boulder brevet and I have been really pleased with it. Even less expensive is to find a suitable old used mountain bike (that are practically being given away now because everyone thinks 26inch wheels are obsolete) and do a drop bar conversion and install the rat trap pass tires. If you think about it, 8000 dollars for a mass produced plastic bike with numerous design flaws is ludicrous. I get that it is a zippy bike, but for that much money you can get a well made steel bike that will perform just as well if not better, and last a lifetime.

      • One minor point: The Diverge’s price has come down significantly – now with mechanical derailleurs instead of Di2.

      • François says:

        Thanks Conrad for your input ! I do agree, but my budget is actually much lower than the carbon diverge. My budget is more around 1500 dollars. I’m a newbie so building a bike myself is too complex for me. I’ve tried the old diverge and the sequoia (juste have specialized shop bikes around me). The diverge (even the low cost one since it has the same geometry) has that planing feeling and yes it feels great! On the other hand, fenders and racks at the same time on the diverge : not really possible I think. The sequoia, I love the more upright position, it’s steel, and more possibilites for racks and fenders. But I’m not sure to really use it for what it’s made for. I would be able to order a surly (Gert suggested the cross check) but I will not be able to test it before. Thanks again for your advice.

      • Chris P says:

        Conrad–I’m sort of doing what you suggest. I have an old mountain bike that I just put Naches Pass tires on as a first step toward what I hope would be a bike that I could use on long gravel rides or even something like the Tour Divide, which I fantasize about doing perhaps next summer.

        The tires have made a huge difference already and the next step is a new fork.

        But I can tell I’m going to run into at least two problems: one, I think my frame might be rather heavy, and two, I don’t think the geometry will end up being good for all-day riding. Top tube is too short, I think, and there is something off about the fork angle or trail, though this is beyond my ken. Even if the project fails

        So I wonder if there are good old mtb frames out there that would have a good geometry for touring/long-distance riding. Thoughts?

        The other problem I’m running into is cost: when you start buying new components, they add up fast and a new bike can end up costing not much more than a free or cheap old one, especially if you have to pay labour to do part of the assembly. I’m not one to shop around on the internet or scrounge through used parts bins at the local community bike repair place, so I’m sure there must be a way to keep these costs down that I’m not pursuing.

        So if it fails as a project, I’ll look elsehwere. Soma seems to have some possible steel-frame wide tire possibilities in the Pescadero and Fog Cutter….

  7. Laurent Fournier says:

    Hey Jan, I had kind of a spooky experience this afternoon. I was listening to your comments in the Cycling tips podcast about frame stiffness while driving down from Col de Rousset when I saw you and your stoker speeding up the road on your tandem! You looked terrific by the way in comparison to the 2 other tandems behind you which seemed to struggle their way up the mountain. The strangest part of all is that we do not know each other. I just happen to have read a couple of your books and was involved in getting your tyres to the store of the Danish Cyclist Federation in Copenhagen (I live in Denmark). Anyway, have a great time riding in the Alps and keep up your great and inspiring work.

  8. David Lewis says:

    When you built up the Firefly, what rims did you use? 26″ rims appropriate to the Rat Trap Pass seem a bit hard to find, especially in carbon.

  9. Gert says:

    Randonneur bike is a good term for a fast tourer. Fenders and light being optional.
    I more or less stumpled into getting mine. As I in general cannot use standard bikes because the top tubes are to short and bb drop to large, I suddenly found that Surly made the cross check frame with my top tube length and a high bb so I could fit 185 mm cranks. I bought it for riding in the woods in winter. Now I use it for everything. It is a bit heavy, but it was cheap, and I can sit exactly in the same riding position as on my custom built “race bike” frame.
    It can be a naked cross bike, and I can fit fenders, racks etc.
    For me even though I ride without fenders it is my randonneur bike.

    Not that You asked me Francois but in my wiew, it is a way better cheap option. Also because the Diverge in 2018 is getting shorter top tubes giving a more upright riding position. Not much racing in that. And they lower the bb even on the 64 cm frame.

    • What a coincidence! The Col du Rousset was fun. We saw the other tandems a few times when we stopped to take photos. They pedaled smoothly, but their tandems clearly had much more wheel flop than ours, hence perhaps your impression. They had a great time, too.

    • François says:

      Thank you Gert for the answer, so difficult to choose a do-it-all bike for a newbie ! Jan seems to insist on how good it feels when the bike have planing (the feeling of getting in sync with the bike) ; does the cross check has that too ? Thanks for your help !

      • Gert says:

        I do not really know about planing. I would probably have to try many different bikes to find out, what it is. I guess the cross check is probably to stiff to be planing, (relatively heavy and oversize tubing). At the last PBP I met two other guys within the last 100 km on cross checks. One who was not that happy, but that was based on the components of the standard bike, not so much the frame. The other one was like me very happy. He rode 38 mm Barlow Pass on it, and I rode 32 mm Stampede Pass. We both felt it rode like dream down hill, but we both also felt it was the tyres, which did that. I will probably replace it with a custom built frame some time in the future. I bought the frame when it was just below 400 euros, and with all the fun I have had out of it, I am very happy.

      • Harald says:

        As a Cross-Check owner since 2008 or so: While the bike has many qualities in the value and versatility departments, in my experience it does poorly in the performance and planing categories. Compared to my other bikes (a SOMA Grand Randonneur and a Gunnar Roadie), the Cross-Check has always felt dead.

      • François says:

        Thank you Gert and Harald for your help ! The cross-check would be an interesting option. So no planing, but it seems impossible to have it all on a low cost easy available bike! One problem though, I will only be able to order it and not try it before. Is the size tricky to choose ? It’s kind of scary to order a bike without the possibility to try it first, even if it is for 10 minutes or so (I was able to try the diverge and the sequoia).

      • Gert says:

        Francois it is difficult to give advice in that situation. I would probably buy something through a local bicycle for my first bike. Even if they are specialized dealers, talk to them about, what you are looking for and hear what they can do for You. Of couse, You can use the geometry of the bikes You tried, and order something online with the same geometry. But if You run into problems it is nice to have somebody close by who will help.

  10. mike says:

    The latest, greatest bang in the market: One frame, that fits several wheel sizes.That’s how bicycles started with different wheel sizes and adjustable brakes. Now we are back here due to the flexibility that comes with disc brakes.
    There is an advantage for bicycle manufacturers – offer one frame for multiple purposes.
    I’m still wondering how many people really switch wheels of different sizes in the same frame on a regular base?!

    If the handling with e.g. lightweight 42 mm tires (650B) is so similar to to 30mm (700C) – why should I switch ?!
    Wouldn’t an addicted rider, one who feels those small differences and ranks them as important enough to buy and maintain a second wheel set to switch regularly between both, wouldn’t such a person not buy a second bike?!

  11. mike says:

    *grins*
    The next big thing on the bicycle market I would love to buy would be on-the-fly-adjustable-tire-pressure. No matter which wheel size 😉

    • Years ago, I dreamt of that. Use the huge down tube of a modern bike as a pressurized reservoir… Turns out that tire pressure isn’t that sensitive and I rarely adjust it during a ride any longer. But still, would be nice…

      • mike says:

        Agree, too much effort for the need. That’s really a point on wide tires, that compromises in pressure are smaller, because snakebites are generally more far away …

  12. Chris Pavsek says:

    Mike said: (can’t find reply button for his post): “Same feeling climbing uphill steep roads in an aggressive manner. The flexing seems to steal performance here, subjective observation too. If the surface gets less ideal, the wide tire trumps here as well as downhill.”

    I wonder about this too. Does the additional flex of a chubby tire take away power on a climb, especially out of the saddle? Doesn’t that kind of approximate having a flexible rim?

    (That said, I bumped up from 28mm to 32mm tires yesterday (Stampede Pass w/extralight casing), which is a noticeable jump in feel and comfort. Who knows if it’s the sidewalls or increased diameter; my saddle sores don’t particularly care! I’ll definitely ride my next long ride/brevet with them. )

    • Some flex can be helpful for performance, and we’ve found that especially very stiff bikes like the Open U.P. performed better with the tires at lower “gravel” pressures than at higher “road” pressures. So it all depends… Generally, even a wide tire can be inflated hard enough that it doesn’t flex noticeably, if that is what you prefer.

  13. Dr J says:

    Not sure if I understand. You wrote “Specialized Sequoia felt like a mountain bike”. In such case, what geometry does your Firefly have? Because Sequoia’s geometry is far from being MTB-like. in size 58, it comes with a 72deg head angle, 435mm chainstay length and a 100mm stem. Yes, bottom bracket is higher (65mm drop), handlebars are a bit wider and stack is slightly higher as well, but trail is still low (64mm) and in general, far from MTB territory. Maybe if head angle was slacker, but I wouldn’t consider Sequoia to have any MTB heritage. It looks more like a modified cyclocross bike.

    • I didn’t measure the geometry of the Sequoia, and Taiwanese factories are notorious for not matching the spec that the manufacturers provide. It wasn’t just the front-end geometry, but also the position on the bike. All I can say that by comparison to a “road” bike like the Firefly, the Sequoia felt more like a mountain bike. Perhaps a “real” mountain bike would feel even more like a mountain bike?

      The Firefly has a 73° head angle and about 40 mm trail. The trail figure has been lowered compared to a bike with narrower tires to compensate for the much greater pneumatic trail of the wide tires.

  14. Heather says:

    I live in downhill cross mountain bike heaven, most people are on the trails not the roads due to a long standing fear of the traffic and road conditions. I will be spotted riding a road bike on back roads, multipurpose trails, less gnarly trails or old old old grown over logging tracts. I will either be questioned on the spot or hear about it days later. Somebody saw you riding a road bike on ___trail! Are you crazy? How do you do it? I am even riding fairly skinny tires, often with panniers or a rando bag. The irony of living car free in a rural area is that I do not have time to set aside just for mountain biking. So I will take back roads home, or go on adventures after work or come the fun way home from grocery shopping in the next town. Mountain bikes are so inefficient on roads and I truly regret the years I spent riding mountain bikes because it was all the bike shops had and I had stopped wondering where those beautiful lugged road bikes went. Years and years ago before the mountain bike is best for everything trend took over I thought nothing of riding a road bike or old 3 speed on dirt roads and trails. I never lost those skills.
    I had a ‘touring’ bike and it was horrible. Very slow, awkward, overbuilt even though the frame itself was light. It was not much better than the hybrid I was dragging myself around on. So I searched high and low and found the best lightest speediest vintage road bikes that I could find. It a was challenge being short because less higher end bikes would have been made in smaller sizes. It’s all rural miles for me, I am done with cute commuters and loopy girly frames. Someone had the audacity to ask why I didn’t have a hybrid! For me I can’t do drop handlebars so I have flat bars and thumb shifters, but it works for me. If you are too short, arms and hands too small, or your back is messed up drop bars can be a nightmare-never feel you have to have drop bars to make your bike a road bike! There is no mistaking the handling of a road bike even with flat bars on it. My road/rando bikes have platform pedals too. Out of necessity I put a front rack on a cheap old italian road bike for panniers or a rando bag and was surprised. It handles front loads very well and is only slightly slower depending on how much I’ve piled on. It is the most ridden bike even though I have a much faster summer machine. My bikes all have tires that can manage dirt, gravel, mud.

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