[Closed] Any scientific studies on lap times with different wheel sizes?

You'd think there would be something published seeing as most manufacturers claim to have "done the research" and "have the data" before deciding to ditching 26". Probably just mean market research 🙂

Has there been any real scientific studies with riders on a course recording lap times on different wheel sizes? If so could you post a link?

Don't be daft, that would prove what most of us already know, wheel size makes bugger all difference.

Has there been any real scientific studies with riders on a course recording lap times on different wheel sizes? If so could you post a link?

Just spent a few moments seeking this one out - closest I've seen to what you describe:

Just watch the Olympic mtb final and see what the winner was using. If you're slower than him you can be sure it's not wheel size that's the problem.

Don't be daft, that would prove what most of us already know, wheel size makes bugger all difference.

Yeah right 😆

Every trip round the countryside is a race.

To be scientific, it needs to be a double blind test. Would love to see that 🙂

And lots of riders riding lots of bikes lots over lots of different courses and terrains, and doing stats on all the results.

each size has pros and cons, basically no wheel is faster, just faster in one situation.

Yeah right

Get back under your bridge.

That video- he precedes the "scientific" test by saying he's going to find out just how much quicker the 29er is.
He then goes out and proves that is just over 4% quicker.
Make of that what you will. Not science though

And another kitten dies a painful death.

each size has pros and cons, basically no wheel is faster, just faster in one situation.

Yeah but a certain size is faster in more situations than other sizes 😆

A magazine test was quoted and linked to on a recent 29er thread, there was only some data though, not all of it.

It's pretty much an impossible challenge- because you can't change wheel size without changing a stack of other factors, so there's no way to isolate it. (so for example you get boneheaded MBR commentary on how amazing 650b is because it works so well in the completely different new Orange Five compared to the old 26 inch one). But even if you could isolate it, that'd still not be a fair comparison because you'd end up with a basic spec that favoured one wheel size or another- so frexample convertible bikes, which were designed for 26 inch but now have adaptors to take 650b.

So what you're left with is a lot of new model vs old model comparisons, and no surprise, new models are often better, and almost all the new models are 29 or 650b with most being 650b right now. So the best you can hope for is comparisons between either broadly similiar bikes, or the best you can do in each wheel size.

But even then, since there's no such thing as a best bike, everyone'll probably end up going fastest on the bike that suits them best not the bike that is best.

Still there's been some good attempts, the mad scientist Nico Vouilloz tested 26 vs 650b and decided to his satisfaction that 650b is fractionally faster. This is a guy who spent hours machining down and testing different maxles to see which has the preferred amount of flex, after discovering Lapierre had made their bikes too stiff, so marketing aside I reckon if he says it's better for him, it is. But that's only 2 sizes.

I read about one in either Singletrack or MBR, but to be honest the times between different wheel sizes were pretty similar, something like 20 sec in a lap of about 14 mins, so depends if you're after a podium spot or not.

If you really mean scientific, then no. I've never seen anything, in print or online, that would stand a snowball's chance in hell of getting published in a decent peer reviewer journal.

It's interesting to consider whether a scientific test of a bike is even possible. I suspect (for the reasons already outlined by Northwind and andytherocketeer) that it probably isn't.

People will moan that they don't reflect real life, but I'd like to see a lot more lab testing of isolated components though. How about a test of the three wheels (in an identical rigid fork) on a bumpy rolling road. Then you could look at the power required to maintain certain speeds with each wheel size and look at how that varies with, for example, tyre pressure. It wouldn't be a "real world" test, but it would show whether any differences were bigger than the natural variance that you would see in day-to-day riding.

I'd be interested in both your comments on the test I referred to - I'll try to find the thread.

I upset a few people by questioning how scientific it was.

And people question hi fi magazine claims...

Do people who don't think wheel size makes any difference also think head and seat angles make no difference?

JCL nobody is saying it makes no difference just it's hard to tell in many ways. The change in wheel size also leads to other changes like angles.

The nico test was a great example where the difference was down there in the margins of error but people still extrapolated it to make it seem like he could have finished a round the world trip 5 weeks faster.

I have no issues with the fact that some bikes with some wheel sizes do some things better. Though to say it's all about wheel size is a little ambitious. But I'm sure you will be back to tell us Chris Froome should be doing the tdf on an enduro 29

The nico test was a great example where the difference was down there in the margins of error but people still extrapolated it to make it seem like he could have finished a round the world trip 5 weeks faster.

The test Nico did was between 26" and 650b. The difference there is marginal as we know.

Anyway I think what I asked is a valid question.

Worth noting that any off road back to back comparison can never really be a back to back comparison.

Unless of course you can guarantee that the rider will hit every bump at exactly the same angle, have their weight on the suspension in exactly the same way at the same points, etc. Way too many potential variables.

In short, try some bikes. See what feels best/fastest/nic(h)est for you, then buy it.

Before I bought a 29'er for racing duties I did some timed laps with a hrm of a route to see if they were faster.
So, similar weight bike, just 26" vrs 29" wheel. Xc course, no big drop offs or things. (Whinlatter north loop)
I rode my 'race' bike around the course then did it again on the 29'er with a similar heart rate. I was 3 mins quicker on the 29'er. I then thought I could of been over excite able on the 29'er so I rode out and about for 2hrs before returning to do the test again. The second time I was 1min quicker on the 29'er.
This WAS NOT scientific or controlled but I just wanted to see. Since then I sold the 26'er and got a 29'er.
For me and what I do I find them quicker, however, they are not as nimble.

Horses for courses.

What CFH said ^^.

There's no way it can be scientific cos you can never replicate an exact lap. Same power, same effort, same lines, same weather conditions is almost impossible. Not to mention any inherent bias of the rider - maybe just easing up a touch here or trying a bit harder there in order to rig the result.

Some magazine (MBR??) did some timed laps of Mountain Mayhem one year on FS vs HT by having a load of hire bikes which were as near identical as possible other then the rear suspension. They found that FS was faster although predictably at the time, MBR was convinced that the only way anyone could ride off road was on a 6" travel FS...

Second time around... better warmed up, better line choice... etc. Too many variables.

I guess looking at the sharp end of competition (e.g. World Cup stuff) is a good indicator. Some wheel sizes are definitely more prevalent in different disciplines so some riders definitely think one is quicker than the other (though there are the obvious commercial factors.) Despite this there are riders, all of similar ability, on all different wheel sizes putting in competitive times and winning races. For example, in XC racing, while 29ers are currently dominant in terms of numbers, it's not like all 29ers finish way ahead of all 650B, finishing way ahead of the 26ers. It's nowhere near being that clear cut as far as I can see.

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Drac, sorry, though i think I can be forgiven as this is the first wheel size thread I've ever posted on!

Here we go. Don't say the test in this thread isn't scientific though or some people will get upset!

http://singletrackworld.com/forum/topic/29er-for-xc-racing

I'm tempted to set one of these tests up myself when I get time.

I may just do that in the summer using multiple lap times from different days for both sizes and correlate power meter readings to try and show effort levels were consistent etc.

If there's no screamingly obvious difference, why would it matter to anyone except elite racers?

I've done loads of laps of local trails trying out stem lengths, tyres, different fork travel on a frame, etc etc. Never once have I thought of timing anything : ) It either feels better or worse. What else matters? If it feels right you'll probably either go a little quicker sometimes or be comfier. No science.. same for wheels. If there was any real science we've had about 10 years to do it. None so far. I don't believe there is any. There's some fairly simple mechanics and your preferences. If that doesn't answer it for you, be happy that you don't care!

stick 650b logos all over a 26er frame, wheels and tyres, and I bet the average STWer would probably get a different time to the identical bike with normal 26er logos.

and as I keep saying. every ride is a race.

And another kitten dies a painful death.

That test's a perfect example of why it's so difficult to do this- the weights of all the bikes are the same, which is automatically biasing towards larger wheels since if the spec was equivalent, the bigger wheeled bike would be heavier. 3 different bikes. Same tyres but that doesn't mean equivalent performance. None of these things are unreasonable of course but they make the test imperfect.

(another thing that makes the test imperfect is the wobbly results frankly)

How many people on here race regularly? For them I can see some sort of point to this debate. For everyone else, who gives a crap about whether one sort of bike might be a few seconds faster than another????

No, there is no scientific evidence and there never will be- too many variables and certainly not in the interest if manufactures when marketing alone is doing such a good job.

My thoughts from the thread Cynic-Al linked earlier

However, as Matt as acknowledged himself it isn't a perfect test. It is a good test but hard to draw any real conclusions besides the small amount of data providing some evidence for one user that the 29er appears to be the faster bike and certainly not any slower than the 26er or 650B on the one course tested. To say it is scientific though isn't really too accurate though IMO. I don't claim that a "scientific" test is easy though so I am certainly not intending to criticize and couldn't do better myself!

The small number of observations is an issue. Day to day variability usually requires repeat tests across 3-5 different days for most applications. Inter-subject variability? Again, 10 people would be the absolute bare minimum for anything like this to be published usually but some quick calculations based on the data might require a far higher number of testers are required. An interesting question is do 29ers yield advantages for all? Are 29ers advantageous across all courses? You can keep the mean power output the same between repeat tests but is the total power delivered equally in the same magnitudes and at the same times between repeat tests throughout the duration of a lap? Are the lines taken each lap and the energy used descending (almost impossible to measure!) consistent? You'd imagine a skilled racer can control this pretty well but something like Principal Component Analysis could identify areas of highest variance between power and HR waveforms of multiple laps then use PC scores to determine if there is statistically significant differences in how the mean power (or HR) is applied across the lap. The tester was also not blind to the bike being used so may bias the results. A placebo 29er would be an interesting test too If the bikes were of equal weight overall then the rotational masses and distribution of weight would presumably be different between the bikes. How do you go about making the bikes "identical"??? You could go on and on!

The test may not be scientific but the reality I think is that there are too many variables to control or account for to actually conduct a "proper" scientific test. Anyone who tried would leave themselves open to criticism one way or another and lets be honest it isn't in the interest of manufacturers when the easiest solution is to just make all bike in one wheel size and force the change Experienced racers certainly don't seem hindered by 29ers. All I know is Matt could ride a BMX and beat me on the pimpest whatever bike on any course

Science and wheel size? That's like matter and anti-matter - can't be combined into anything. Except possibly an earth-obliterating explosion

If you have two bike on a tread mill wit the same gearing, a 26 and 29 get a robot to turn the pedals at the same power output and time. Would one bike go further than the other?

Obviously other factors involved like quicker turning for 26, and smoothing out bumps for 29 etc. But surely the math geeks among you could figure out those.

My examples are crude as im not a scientist. But surely if there is a difference then these thing can be narrowed down to a few simple tests to prove where the majority of speed actually comes from?

PS I don't actually care about the answer. But I just strikes me that claims that it is immeasurable seem unlikely.

How many people on here race regularly? For them I can see some sort of point to this debate. For everyone else, who gives a crap about whether one sort of bike might be a few seconds faster than another????

I agree.

I only currently have a 29" but I have a friend that's faster who has comparable 26" and 29" bikes (actually the 26" is over two pounds lighter) If he rides the 26" I"m on his ass, if he rides the 29" he's gone. We've repeated it countless times on different courses and it's always the same.

Seosamh77: your robot leg test is do full of failure it's not true.

It would prove nothing that simple sums with rolling radii and gear calculations wouldn't predict with 100% accuracy.

It would not in any way show that one of two (three? More?) different bikes ridden at the limit of rider skill and endurance would always be faster everywhere, every time or even same place/time as it's just not possible. By the time you've standardised the variations out you're left with a 'test' so meaningless as to be 'I like this one better'.

And that's fine. But please don't try to call it scientific. An average person with no particularly good skill or fitness levels would probably find the larger wheel size flattered their efforts by moving faster for less effort and not getting anywhere near any situation where the considerations of vehicle size meant a smaller bike could be faster. That's not science, it's product marketing. Personally I ride because it's fun and I enjoy it. The bike industry keeps trying to sell me things it promises will make me faster and enhance my fun. As with the n-thousand pound gramme scrimping carbon roadie, the rider is cheaper to improve. I've seen 26ers moving faster than I can make them go. Once I've achieved that level, maybe new wheel sizes will be relevant to me... unless I wear a bike out or go mad before then... 🙂

JLC- Ever thought the 29er is faster as it has essentially got higher gearing if it is the same? Anyway asking which is faster is all wrong for a lot of people. The real question is which is more fun and luckily the answer is all of them depending on what you are doing.

The real question is which is more fun and luckily the answer is all of them depending on what you are doing.

Here here!

Now can we stop this kitten killing spree?

My original question was has anyone done a scientific experiment and could you link to it... not can we re-visit the merit's of fun vs marketing vs marginal gains again.

Thanks to those who have answered what I asked. The response about vs a mate who has two bikes is interesting and what sparked me to ask as I have a mate who I ride with regularly who has moved to a 29er and suddenly seems a fair bit fitter than before.

On the flat/rolling stuff it's probably faster but thats the bit where it's more noticeable. The missus went to a Tallboy from a Blur LTc which is 2kg lighter and shorter travel so apples and oranges really. She does motor on up the hills and on the smooth these days but not on the tech so much.

But you cannot do a scientific study as faster in one area may mean slower in another.

Take the example of skis. There are loads of different types and the ones that are fastest for Olympic downhill skiing would not be great or fun for most people or fastest in all conditions.

Tyre pressure has more influence than wheel size in my opinion. (Speaking from experience after pumping my 29er tyres up too hard this morning and being pinged all over the place.)

It would not in any way show that one of two (three? More?) different bikes ridden at the limit of rider skill and endurance would always be faster everywhere, every time or even same place/time as it's just not possible. By the time you've standardised the variations out you're left with a 'test' so meaningless as to be 'I like this one better'.

Think this is why it's useful to look at top level of competition. You have a lot of rides who are evenly matched in terms of ability. And you have the best bike available, whatever the wheel size, optimally set up for each rider. And in that arena (be it DH, XC or Enduro) all wheel sizes can get competitive times, and no one wheel size is dominant over the other in terms of lap/run times.