Myth 14: More Lumens Make a Better Light

As the days get shorter, many cyclists are thinking about lights. How do you measure the quality of a headlight? It’s tempting to look at how many lumens the light puts out. After all, brighter is better, isn’t it?

On the road, what matters is not lumens, but lux. What is the difference?

Lumens looks at the source: how much light does the headlight emit?
Lux looks at the result: how much light arrives on a given surface area of road.

In the image above, the circle on the left is the wall projection of the beam. Its brightness multiplied by its size give you an idea of how many lumens the light puts out. The side view shows where the light is going. The plan view illustrates how many lux arrive on different parts of the road surface.

Lumens can be expressed as a simple number, but lux depends on where you measure it. This makes lumens easy to measure, while lux are difficult to quantify.

The headlight shown above is a typical high-powered bicycle headlight. It’s got an impressive bright spot with a lot of lumens. But when you look at the road surface, you see that not much of that light arrives on the road. The symmetric beam shines almost half the light into the sky, and there isn’t enough left to illuminate the road. In addition, you are blinding oncoming traffic, which isn’t just a bother, but can be dangerous on narrow roads.

What if you orient the beam downward? Now you have a super-bright spot right in front of the bike. Why is that bad? It makes it difficult to see into the distance. Your eyes adjust to the bright illumination, and you can’t see the darker parts of your field of vision.

It’s like walking out of a brightly-lit room at night – you can’t see until your eyes have adjusted to the darkness. On the bike, the bright spot just ahead prevents your eyes from adjusting to the darkness. You feel like you’re peering through a layer of fog. It’s difficult to see the darker road surface in the distance.

This is especially tiring when descending mountain passes, where you need to see far ahead. In the city, you can’t see potholes, debris and other obstacles until the last moment.

If we make the beam square and even, it gets better, but we’ve fixed only part of the problem. The wall view looks great, but looking at the side view, you notice that the beam hits the ground at different angles: steeper near the bike, shallower further away.

The dashed lines split the beam into thirds. Notice how the lower third illuminates about 15% of the road surface, while the upper third spreads its light over a much greater area (~50%). With an even beam, the area in front of the bike is three times brighter than the distant road surface. You’re still peering through a fog of brightness.

The way to solve this is to use a layered beam – shown above is the SON Edelux II headlight. The wall projection (left) shows how the light intensity increases upward. This compensates for the different angles at which the beam hits the ground (side view): The lower portion of the beam is darker, because it illuminates less of the road surface. The upper portion of the beam is brighter, because it spreads its light over a greater surface area. This ensures an even illumination of the ground ahead of the bike (plan view).

At the top, the beam is cut off. This eliminates any wasted light and ensures that you aren’t blinding oncoming traffic.

With a light like this, all the light goes where you need it. None is wasted, and the ground is illuminated evenly, making it equally easy to see objects near and far. You aren’t peering through a bright ‘curtain of light,’ so your eyes adjust to the darkness. This in turn allows you to see outside your narrow beam, for example, when deer are about to cross the road.

There are very few headlights that use a layered beam. The two best known are the SON Edelux II (above) and the Busch & Müller headlights.

Layered beams are used by car headlights, so why don’t more bicycle headlights use them? The answer is cost: The complex reflector takes much R&D to develop – the cost is in the $100,000s –  and to work properly, the LED must be located with great precision. If you ride at night, you’ll gladly pay a bit more to get a light that illuminates the road evenly.

So what matters isn’t how many lumens your light puts out, but how brightly and evenly it lights up the road surface. When we descend gravel mountain passes in the middle of the night, we need lights that show what’s ahead without fatiguing our eyes. It’s fair to say that the SON Edelux headlights have revolutionized how we ride our bikes at night. That is why we sell them at Compass Cycles, and why we distribute them to bike shops, too.

More information:

  • Lights in the Compass program
  • Other posts in this series:
    Myth 1: Wider tires are slower
    Myth 2: Titanium is lighter than steel
    Myth 3: Fenders slow you down
    Myth 4: Stiffer frames are faster
    Myth 5: An upright position is always more comfortable
    Myth 6: Tread patterns don’t matter on the road
    – Myth 7: Tubeless tires roll faster
    – Myth 8: Modern components are lighter
    – Myth 9: Fork blades don’t flex
    Myth 10: Stiffer forks steer better
    Myth 11: Rear tires should run at (significantly) higher pressures
    Myth 12: Disc brakes work better than rim brakes
    Myth 13: Leaning without Countersteering
    Myth 15: Marginal gains

Illustrations of beam patterns courtesy of Schmidt Maschinenbau.

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 the high-performance components we need for our adventures.
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47 Responses to Myth 14: More Lumens Make a Better Light

  1. RickH says:

    I had an older B&M and replaced it with a newer version that had a different reflector on the light. Unfortunately the newer (brighter) model had a more distinctive letter box type of bright square with lighter diagonal projections to the side and I didn’t like it. I bought a IQ-X 100 lux model, but wasn’t happy with that beam shape, although bright it was. I then made a comparison of reflector shapes and notices differences.
    One thing I haven’t been able to do is compare the Edelux light with the B&M variety.

    Riding with friends at night who have them showed that were clearly better than mine. It would be good if I could get a comparison image of all the lights.

    • One issue with plastic lights: The LED isn’t located with the same precision, so the beam pattern varies more. If you get a good one, it’s probably great… On the Edelux, the housing is precision-machined from aluminum, so the LED’s position is always the same. The aluminum housing also offers better cooling, which improves the performance of the LED. (Many B&M lights now also attach the LED to a metal cooling surface.) Overall, I don’t think you’ll find a better light than the Edelux II.

  2. David Morgan says:

    Amazingly informative!!! Info and perspectives we would otherwise NEVER obtain.

  3. Eli says:

    I switched from round-beam battery lights to an Edelux II last year and, while I agree that it does a better job illuminating the road, I’ve struggled because it does not really light up reflective traffic signs at all (as they are usually placed above the beam cutoff). This makes navigation difficult. I can angle the light up, but then I lose illumination of the road surface immediately ahead of me. I’m curious how other users of Edelux and similar lights handle this.

    • When you orient the beam at the horizon, you’ll illuminate the road signs without blinding oncoming traffic. You are right, though, the Edelux II doesn’t put much light in the first few meters in front of the bike. We find that this isn’t really a problem, because we want to look ahead and select the straightest line through the maze of potholes, debris and obstacles, rather than swerve to avoid them at the last moment.

      Putting more light right in front of the bike would mean losing illumination elsewhere, or increasing the resistance of the generator hub to produce more Watts.

      The only time when the beam cutoff can be an issue is when riding brevets at night, and having to navigate by street signs. Reflective signs require very few lux to light up, but out in the country, many signs are old and no longer reflect, if they ever did. You can see the street signs from a distance, but as you get closer and they loom almost overhead, they no longer are in the beam of the light. We’ve suggested to Schmidt to put a little more light above the cut-off in the future – but not so much that we blind oncoming traffic. We also find that a headlamp on our helmet illuminates the signs, plus it also allows you to see the cue sheet on your handlebar bag.

  4. Dr J says:

    Thank you Jan for addressing this ongoing problem. This is my biggest complain about most bike headlamps. Companies seem to push those 1000 lumen “death rays” without actually understanding how a headlamp should work properly.

    If I could add anything, I would even simplify it and say it’s not lumen vs. lux but just a symmetrical torch-like pattern vs. a shaped pattern with horizontal cutoff.

    There’s a good reason why all properly-built bike headlamps are German-made. It’s the only country I know that has a detailed standard for bicycle headlamps requiring horizontal beam cutoff.

  5. Kyle says:

    For those of us – few as they may be on this site 🙂 – who don’t have immediate plans or means to make the upgrade to a Edelux type light + dynohub, can you make any comments on how to make the 1st example less bad?

    For instance, I have read elsewhere that getting your light as low as possible is advantageous – both in reducing glare for oncoming riders and for grazing the beam along the ground surface so there is less of a hotspot. This makes intuitive sense to me, but any thoughts on its veracity? Any other tips?

    This is a timely article as I am about to diy a low mount for my previously handlebar mounted light.

    Thanks for your great work!

    • As you suggest, mounting the light lower allows you to make the beam more parallel to the surface. Depending on your light, this may spread the hot spot over a larger surface area, because you are using only the middle part of the beam to illuminate the path ahead. On the negative side, you’ll blind oncoming traffic more, because the light isn’t angled down any longer.

      The lower beam makes it easier to see potholes and obstacles by illuminating them at a slight angle, which gives them more definition due to the shadows it creates. A helmet light is worst in this respect, because its beam is parallel to your line of sight, and you don’t see any shadows.

      Experiment and see if you can improve your light pattern. It’ll be a compromise, but better than nothing. Just one thing: Please don’t clamp your light to a tapering fork blade – the light almost inevitably will slide down and rotate into the spokes. I know of some very bad accidents…

      • Kyle says:

        Thanks!

        Very good tip. That wasn’t my plan, but very good to keep in mind esp for future projects.

      • heather says:

        Oh yeah! I was thinking about getting one of those adaptors that can go on the fork fender/rack eyelet or front rack mount. When I have my front rando bag on the rack it sits too high so the bike light on the handlebar is blocked. I have to ride in the dark with a box shaped shadow. I keep imaging duct taping the light to the front of the rack. The never ending increase of lumens is just so tempting and they are getting less expensive as every new product upgrade comes along. I have trouble seeing at night in the miserable rain and oncoming traffic. I need bright lights, but I also feel bad when I scare bears and see them running because the beam was so bright!

      • You are right, how much light you need at night depends on your eyes. These days, all but the cheapest lights have enough lumens, so the beam pattern is becoming more and more important. I still recall the days of halogen bulbs, when you had to choose between a long, but incredibly narrow beam, or a wide beam that didn’t reach far. Now we can have it all, and even when descending mountain passes at 70 km/h (45 mph), you don’t outrun your light’s beam.

      • Garth says:

        You could experiment with blacking out the top portion of your Example 1 light, such as with black paint on the inside of the lens. It’s ad hoc but I’ve seen such black paint utilized in certain motorcycle sidecar situations.

        On a related note, I recently drove a Chevrolet rental car with a very limited top portion of the beam. Perhaps the headlights were pointed too low but on a dippy road I became dizzy because instead of looking past the tops of the headlight illumination, my eyes went up and down with the rise and fall of the lights. Oy.

        Another factor to think about is the temperature of the emitted light. When LED flashlights first came out my son and I discovered on a camping trip that we preferred a cheap led light to the big incandescent one. Why? Because the LED light matched the color temperature of the moon and expanded our field of vision, we could see beyond the otherwise yellow tunnel created by the Mag Light.

        Just curious, though, about a yellow accessory fog light lens for the Edelux. Are yellow lenses really helpful or just nostalgic?

    • Neil says:

      One option could be a battery headlight with a better beam shape. The B&M Ixon IQ Premium worked very well for me before I switched the last bike to dynamo lighting.

      • Kyle says:

        Nice, I’ll have to check it out.

      • John C. Wilson says:

        A warning about B&M Ixon IQ Premium. If you allow the battery to discharge entirely you will fry the electronics. This would include simply being out too long or being delayed by a mechanical. And of course when you find your way to new batteries you still have no light. If you allow the battery to discharge entirely neither B&M nor their retailers will honor the warranty. Information provided with the light does not warn of this.

        Why does something so simple as a headlight require electronics?

      • Garth says:

        If you can access to the weatherproof inside of your light you could obtain neutral density gel filters from a phography store (eBay) and experiment with dimming select portions of your beam.

        There’s no regrets about a well-designed headlight such as the Edelux, though. Quality truly is remembered long after price.

      • snilard says:

        @John C. Wilson: It is quite simple in principle.
        Battery has some voltage. It is higher for charged battery and lower for empty (4.2V to ~3V for li-ion batery). Different LED light intensity is dependent on current (higher current – higher intensity, but it is not linear dependence). This LED current is dependent on voltage, temperature (higher voltage – higher current, higher temperature – higher current for same voltage, but it is not linear dependence) and it may change piece to piece a bit. Usual working voltage of white LEDs is ~2.5 to 3.5 V.
        As You can seet these voltages are not same. You can place resistor between LED and battery to burn voltage difference. But this will mean that Your light will be very bright on charged battery byt very weak on discharged on. To solve this issue You can place some “smart” resistor what would change it’s value to pass specified current to maintain same intensity for whole battery voltages. But there is still problem that Your LED voltage may be higher in high intensity than voltage of Your battery. You can use two batteries in series to get higher voltage (6 – 8.4V).
        So You have two batteries in series and You use “smart” resistor that passes specified current. This “smart” resistor simply burns diference of voltages to heat. Voltage difference is 2.5 – 5.9 V in this setup. It means that efficiency of this setup may as low as 29%. That is very low.
        But there is better way. You can use switched-mode DC/DC voltage converted (https://en.wikipedia.org/wiki/Switched-mode_power_supply). This converter is way more complex and delicate that linear voltage converter what I called “smart” resistor but it operates at much higher efficiency. It may operate at >95% efficiency. Converters in bike lights have to be cheap so I would say that it operates at >80% efficiency. You can imagine switched-mode converted as high frequency on-off switch with smoothing circuit. You regulate output voltage by changing on/off ratio. There have to be some electronics what precisely measure voltage or current and changes on/off ratio of the switch. This electronics is not simple.

    • DarinM says:

      B&M makes some battery powered lights with reflectors and beam cut-offs. Not widely available in the states but I think there are a few sellers.

  6. Thomas Prehn says:

    Great post! We have long since past the state of our ability to produce enough light. I applaud that companies are now looking at how to actually use appropriate design and technology.

  7. kai says:

    avoiding partially naked leds and instead using lenses or indirect reflectors is more efficient, and a good start for a useable light without blinding or self-blinding.

    once there, more lumens are of course always beneficial for a better light. but as this article points out, not enough in itself. however if you dont have the power of the light source to start with you cant distribute light where you want it.

    so therefore i somewhat disagree with the heading here:)

    in germany as you most likely know Jan, people are instead of lumens preoccupied with maximum light on the road expressed as lux values. enter keyhole albeit layered light patterns with optimized lux values in a very narrow sector in the distance, and virtually nothing to the side or in the nearfield. althought nearfield should not be so bright that it blinds the eyes it should nevertheless be there, and preferably quite wide.

    so both lux and lumen figures are clearly higher with better lights, but neither of them have much to say over useability if you don know the light pattern.

    then redundancy; a most important factor when it comes to lights (as it is with brakes), and i therefore use a pair. can thus get something from both worlds, a layered german-type light for distance, and a lens-type wider light angled down for nearfield. and mostly on a low setting so not disturbing oncoming traffic.

    increases useability a whole lot.

  8. Thank you for writing this. With the continued battery and LED improvements, many battery powered “bike” lights being marketed to cyclists have an brightness level similar to that of a car’s headlight and a round beam pattern, we will start seeing legislation governing bicycle light design (like Germany has done). Essentially we now have bunch of cyclists riding around with a car high beam strapped to their bikes. This is dangerous for all road users.

    The cynical side of me figures most of the manufactures have got into the habit of repackaging their trail lights as “urban” lights. This was especially true in the first wave, but as the “urban” market continues to expand and more urban specific features are added, it baffles me that few if any bother with optics! There are a few exceptions (e.g., Specialized Flux lights – but the light shaping while better than most is not as good as Schmidt or B&M which are StVZO compliant), but so far most offerings look pretty bleak.

    I used to run a dynamo light for many years (E6 then B&M LED light), but found they don’t reach deep enough in the rain to ride at full speed so I ended up supplementing with a trail light as a high beam, and now just use a Specialized Flux Expert as it had the shaped light low beam and high beam combined in one package which simplified things for me. That, said, I still preferred the beam pattern from the StVZO compliant lights like the Edelux… perhaps I need to build up a dynamo wheel again…

  9. Emmerich says:

    Slightly off-topic: is there an Edelux variant that can be powered by 5 v only, e.g,, by USB? I ask this since on one bike I have a USB setup already (more for powering USB devices like phones), but would like to add this existing power source for lights as well, when needed.

  10. Phillip Cowan says:

    I’ve been using battery powered lights so far. However this winter I plan to build a generator front wheel. That’s the easy part. Then I have to choose a light. The two front runners in mind are the Edelux II and the Sinewave Beacon. You make a strong case for the Edelux II and I believe it has the best beam shape on the market and is probably superior to the Sinewave in that respect. However, I think the Sinewave is probably equally well made (in the U.S. even) and it has that damned USB port so tidily built into the back of it. To someone like me who can scarcely tell the difference between lux and lox the ability to charge my phone out in the middle of BF Egypt is a very attractive feature. Any chance that SON may one day incorporate a USB port into the Edelux II design?

    • The symmetric beam shapes are more noticeable with brighter lights, so I feel that the more lumens you have, the more important the beam shape becomes. The Sinewave Beacon has a symmetric shape like the top graphic. On their web site, Sinewave recommends the Beacon for off-road use, where your front wheel rarely points in the direction you are headed, and thus a symmetric beam shape may make sense. On the road, I think you’ll prefer a more sophisticated layered beam.

      USB port: When we visited Schmidt this summer in Germany, we talked a lot about USB ports. It’s a neat idea, and something I’d love to have on our lights. The biggest issue is that without a buffer, you risk damaging your devices when you stop and start, or if you ride just at the speed where the electronics turn the charger on and off. Most separate chargers have a battery that keeps the charge going even when no power comes from the generator, but that battery is too large to fit into the headlight. (The relatively large size of external chargers is almost entirely due to the battery.)

      I have some ideas how to work around this, and we’re discussing ways with Schmidt to make an Edelux with a USB port, but SON won’t put products on the market until they are perfect in every way.

      • Gerard says:

        If only there was some space nearby to one’s headlight to store a flat lithium battery, for example in a canvas pocket built into the rear or floor of a front-mounted bag…

        🙂

        I’d like to think there was a market for battery-supplemented lighting systems like this. Would be great to see the power pack integrated this way and also available for USB charging for phones etc

  11. The Phillips Saferide dynamo 60 & the battery Saferide 80 were/are fantastic lights with great beam patterns. Spaninga took over their design when Phillips opted out of bike lighting. I don’t know what the S’ga versions are like, but the Phillips ones are worth chasing down. I had a B&M Ixon Premium that ran on torch batteries that was absolute rubbish: well shaped beam, but dim, short battery life, and fragile. I do think that dynamo lights are great and will always use them for general riding, but for really fast riding on country roads with lots of critters and away from traffic, a trail light is a better option as a high beam for my 60+ years old eyes.

    • kai says:

      the heralded philips saferide 80 was a good example what you can achieve with intelligent beam design and only 270 lumens. but with so little light to start with compromises had to be made, and the nearfield is too dark when you meet oncoming traffic, also the beam is narrow by today’s standards.

      unfortunately the lamp had a most unsatisfactory power system and would turn itself indefinitely off after only 45 minutes.

      there is a number of better street lamps today. for example cateye gvolt80, just to name one. two to three times as wide beam as the philips and two hours on full blast which is about 800 lumens and 80 lux. it warns well in advance when its time to dim, and in addition also has reserve power. and batteries you can easily change when on the road.

      report have come that the spaninga is unfortunately not up to it, too dim. and the same narrow beam as the philips.

  12. ryanfrancesconi says:

    Riding off road speeds are generally slower and you want more light closer to you, so a symmetrical beam is supposedly a better choice in that case.

  13. Conrad says:

    I can’t say enough nice things about the Schmidt hubs and Edulux lights. Its so much better to have a good light all the time without ever having to do anything. When you consider how well they are made, and that they will last forever, and that you will use them almost every day ( in Seattle at least) , they are also the best bargain around.

  14. scott g. says:

    B&M have the new IQ Space battery light, 150lux max, or IQ Core 50lux battery light.
    Cateye also make lights with a shaped beam, the GVolt 80, 50 lux, but you have buy
    them from Germany.

  15. Ken says:

    I currently use B&M CYO Premium lights on both of my bikes that have dyno hubs. I have been pleased with them on the road. But I train a lot in the evenings on a Multipurpose trail that is a few blocks from my home. It is not a typical rail to trail conversion but has many ups and downs and tight turns. I find myself either riding with a Light Motion Stella on my helmet to supplement the dyno light or using a Light and Motion TAZ on my handkebar so I can see around the corners.
    The cutoff the the B&M Cyo has which makes it such a nice light for the road makes it ineffective when your are leaned over taking a tighter corner.
    I really like the beam the TAZ has and wish you could get something like that for use with a dyno hub.

  16. Xavier says:

    Do you have any opinion on taillights design? I sometimes wish we would have more options for wide-area taillights as I find tiny taillights a bit blinding. Which makes it also harder to understand the speed and position of the bike. Other riders seem to share this opinion: https://ridefar.info/rider/safety/active-lighting/#Function_3_Lights_That_Communicate_Position_Speed

    • The Compass taillight puts a reflector in front of the LED. That diffuses the light, which makes it much more pleasant when you follow closely. Yet from a distance, approaching traffic sees the same lumens as from a point source, so the visibility is the same.

      I am surprised that no other taillights seem do that. The reflector also serves as a safeguard in the (unlikely) case that the taillight or its wiring fail.

      • Xavier says:

        I have the Compass taillight on my Joshua Bryant but I never really had the chance to ride behind it. It diffuses the light from the led AND reflect the light from incoming cars? Neat!

        Does this kind of ‘transparent’ reflectors have a name? I should modify my battery lights to fit such a reflector.

      • All plastic reflectors are translucent. However, not all reflect well. We tested half a dozen reflectors until we found one that reflects well. To test them, put them on the rear bumper of a car. They should reflect as well as the reflectors in the car’s taillight. (The standards for car lights are more stringent than for bicycle parts.)

  17. Mike says:

    Thanks a lot for busting another myth, Jan. I’ve often though about putting some metal reflective tape around the beam of one of my lights to reduce the glare effect, gaining some of the benefit of a light with a cutoff beam without going through the expense of new lights, or a new light + dynohub + wheel + wiring + install.

  18. Richard says:

    Some of the posts here hint at a larger issue: High intensity blue-rich light at night can cause problems.

    “White” LEDs (which are actually phosphor-coated blue LEDs) are the predominant source of blue-rich light. LED streetlights, car headlights and electronic device displays are some of the worst offenders.

    In 2012 and 2016 reports, the American Medical Association states that “Glare from nighttime lighting can [cause] frank visual disability,” and that “intense, blue-rich LED lighting can decrease visual acuity…”

    Blue-rich light was recognized as a problem over a century ago, as evidenced by the Corning Glass yellow “Noviol” headlight lens designed to block blue-violet wavelengths.

    Based on visual acuity research, the French subsequently adopted the “Selective Yellow” headlight standard that specified an upper and lower limit within the yellow part of the spectrum.

    It’s logical that yellow light helps visual acuity. Nighttime lighting was yellow for most of human existence. Intense blue light, a physiological cue to awaken, was until recently not encountered at night.

    Some of us still prefer the E6 over the LED. Glare can be a problem, and on rough terrain, the sharp cutoff is fatiguing.

    Maybe it’s time to resurrect the selective yellow lens.

    • kai says:

      you can always buy the revtronic bt40s, it has warm leds, very pleasant for the eye. however not suitable for street use. have them for mtb. it also comes with a replaceable diffusor lens suitable for running. about 1400 real lumens on max.

  19. ed b says:

    Maybe dynamo equipped lights are not aimed properly because every single light from Mel-Carhaix until after Tintineac on my Retour on PBP 2015 literally fried my eyeballs, especially when I was climbing. The lights on my motor vehicles automatically dip based upon vehicle attitude. Maybe Germany needs and other European Norm. How is there any difference to an oncoming vehicle when a cyclist is descending the other direction. The oncoming rider or motorist is just as blinded by a non-shaped reflector as an old fashioned torch or maybe less so by the old torch. Throw and evenness of lighting is important but so is the tone on the light. Some are very harsh and fatiguing at night. Difficult to get it right.

    • In Paris-Brest-Paris, meeting entire pelotons of oncoming riders in the middle of the night is one of the least fun parts. You immediately see the Edelux and similar lights, because they don’t blind you. It’s also fun riding on a trail and not being able to see the faces of pedestrians – which means I don’t blind them…

  20. kai says:

    if you do some secondary calculations according to friction results on cyclingabout site, on a pbp having a generator headlight off daytime, on at night;

    will cost roughly half an hour.

    are randonneurs aware of this:)??

    • Years ago, we calculated the influence of all kinds of equipment choices on Paris-Brest-Paris times and published the results in Bicycle Quarterly 17. Compared to the advantages of supple tires, the penalty of a generator hub is small, especially once you factor in the the extra weight of a battery-powered setup.

      In any case, the biggest difference in PBP times is at the controls, and it directly relates to fatigue. Riding into a bright spot contributes to your fatigue, which means you’ll take longer at the controls. Key to a speed in PBP is limiting the off-the-bike time to a minimum by moving in and out of controls quickly.

      Beyond that, many of us prefer to generate our own power on a bike. To me, powering my headlight with a battery is no different from powering my cranks with a motor.

      • kai says:

        that was really deep philosophiy Jan! i know about randonneurs that think getting to start should also be self-propelled.. maybe one should include making of the bike and clothing here;)

        of course on a bike for travel generator makes a lot of sense. but i use too many bikes to equip them all this way.

      • I don’t think of it as deep philosophy, but I consider lighting an essential function of the bike. And thus I want to provide the power for that rather than use an e-assist.

        E-assists could give you a significant advantage on a hilly ride like PBP. Start with an empty battery, charge it on the downhills (where a little more resistance takes off little speed since your wind resistance is so high), then use that power to propel you over the top of the next hill (where a little extra power gains you a lot since your speed is low). You haven’t used an outside power source… If they complain about the batteries, you could use a flywheel.

        To me, that sort of ingenuity isn’t what the sport is about. It’s like cyclocross, where they outlawed wide tires because they want to keep the sport true to its roots: riding road bikes across terrain where you shouldn’t really ride a road bike. Chris Kostman called it ‘underbiking.’ I once entered a bike with 54 mm tires in a (dry) cross race, and I rode away from the field with ease. I won’t do it again, even if the tire rules aren’t enforced at the amateur level. I enjoy riding my Alan on its (relatively) skinny tires. (But I won’t take the Alan on a ride where we descend gravel roads at high speeds!)

      • kai says:

        very interesting observation.

        of course having a generator AND a battery opens up to cheating like that. and as more. and more bike travellers have this very setup for powering navigators and the like. maybe its easier in competion and randos to enforce, and cleaner after all to have just battery lights?? above all, no batteries should under such circumstances be allowed to be connected to generators.

        and what about electronic shifting??

        no one would question having battery lights on a longer mtb race, where lights are easily 10-20 watts. as far as i know there are no bike generators that strong, and who would want to propel them?

        when it comes to tyre dimensions in cyclocross i personally think it would be appropriate to have a discussion of wider dimensions. after all back in the days when road racing took place on gravel roads, racing tyres were as far as i know wider. besides, cx tyres are generally wider than their marking, so there is already a gray area there:)

  21. Simon says:

    I’m quite glad that B&M has some battery-powered offerings. While I would absolutely love to have a nice generator hub and light, my college student pocketbook blanches at the cost of such a system. I picked up a Lumotec Eyro at the start of this year and have been really impressed with it. Six hours at 30 lux is enough to satisfy my insomniac night riding, and the fork mount is much more secure than some rubber strap (and a lot nicer looking too). The only issue I’ve had with it is that the beam pattern is a bit more narrow than I would like. I would strongly recommend it or another one of B&M’s battery powered lights for anyone who wants an effective beam pattern, but isn’t sure about or can’t afford dynamo lighting. Perhaps if these sorts of bike lights were more readily available in the US, an average cyclist would be more aware of what a proper beam pattern should be like and wouldn’t settle for these flashlight-on-a-mount offerings we mostly see in bike shops.

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