29ers. Are they faster?

I love Ti29ers leap of logic.

His 29er is faster on road so all 29er are faster off road!

You simply cannot extrapolate that – too many unadjusted factors and anyway the on road is a sample of one – so not significant. Are the tyres the same width and at the same pressure? Riding position the same? Gearing the same?

My tandem is significantly quicker than a solo on road and slower offroad – depending on the type of terrain.

Ti29er – Absalon described the course at the recent World Cup in Offenburg, Germany as being "tight, with very technical sections and good climbing". Koerber on her 29'er finished in 15th.

I like 29'ers, infact I like all bikes. It's a bit daft though to say that one wheel size will always be quicker than an other wheel size. When you look at all the evidence and reports it illustrates that both 26 and 29" wheel sizes both have their strengths, and each wheel size will be quicker than the other when the conditions suit them.

In the not to distant future I think you will see XC racers swapping between 26 and 29" wheel sizes depending on the course and conditions, in a manner similar to which they swap between full-suss and hardtails at the moment.

But, if we are going to fan the flames.

Road bikes have gone through loads of wheel size changes over the years, but they now seem to have settled at a 700c wheel size as being the optimum size for the average person. If you measure the diameter of a 700c wheel with a 23c tyre you'll see that it's smaller (or about the same size) than a 26" MTB wheel with a 2.2/2.3 tyre. Why then do roadies prefer a smaller wheel?

Why then do roadies prefer a smaller wheel?

Do they? My next door neighbour has a triathlon road bike he bought about ten years ago when 26" wheels were all the rage.

The smaller wheel size means that you accelerate faster, according to the hype. But now, all these bikes have gone back to 700c (much to his annoyance).

Anyway, I don't think TI29er's results should be treated quite so dismissively – there's clearly something going on. Perhaps the real question is how to judge when a 29er will shine, and when to stick to a 26er.

I said this in another thread, but with a 29er you have more stored energy in the flywheels that are the wheels. The more often you have to turn this energy back into heat (i.e. using the brakes) the more you are penalised for carrying this energy because every time you re-accelerate you have to put it back in. So as a 29er will have lower rolling resistance than a similar 26er the 29er will be faster on courses that require less braking whilst the 26er will be faster on courses with more changes of speed.

With road bikes a course would have to be very bendy for a wheel with higher rolling resistance but lower angular momentum to be advantageous.

I just felt myself nodding off again towards the end of page 2. 😉