I was after a road bike to help the fitness and loose a few lbs for my DH racing and a mate of mine suggested i bought his cross bike. As i could mix things up a bit on that (more my style)
Having riden the road on alls good in terms of what i bought it for. Now having taken it round the local trail center and trails, im supper impressed with how it rolls and keeps speed through the bends etc, if a 29er feels more like this than a 26er then im sold for future trail riding

I’ve a 26er,29er and a cross bike!

Without wishing to wee on anyone’s chips, a 700c wheel with a skinny CX tyre is about the same diameter as a 26″ wheel with a fat MTB tyre. So, the ease of rolling and keeping of speed on a CX bike is more to do with the lack of resistance due to the overall light weight and the skinnyness of the tyre, not the size of the wheel.

Saying that, CX bikes are a hoot and 29rs are good too.

What Mr IHN said.

Although I do like the way 29ers seem to carry their speed, where you have to pump a 26er through a compression or coerner to maintiain speed, the 29er seems to just roll through it.

Given what IHN says, I’m becoming more and more convinced it’s all placebo effect.

What is?

CX bikes ‘roll’, i.e. keep their speed, better than 26″ MTBs as CX’s are lighter and the tyres are skinnier. They’re also more ‘responsive’ for the same reason

29rs ‘roll’ better because their wheels are bigger (although they weight about the same overall), giving basically greater flywheel effect. You could argue that they’re slightly less ‘responsive’ for the same reason.

IMHO of course, but from riding all three types.

CX bikes ‘roll’, i.e. keep their speed, better than 26″ MTBs as CX’s are lighter and the tyres are skinnier. They’re also more ‘responsive’ for the same reason

Hmm – well my crosser is hardly porky (no heavier than most of yours I’m sure), but it weighs just as much as my full-susser. Anyway if you take the whole bike and ride package then 1kg difference in weight is only just over 1%, which is too small a difference for a normal human to detect. Meanwhile, more weight equals more inertia, which from Newton’s Second Law will result in keeping speed better!

You do also realise that on typical off-road terrain fat tyres actually roll faster than skinnier ones?

IMHO of course

Indeed – that certainly doesn’t rule out placebo effect.

my crosser is hardly porky (no heavier than most of yours I’m sure), but it weighs just as much as my full-susser

That suggests a pretty porky crosser or a pretty svelte full-susser.

Anyway, it’s all fun and mainly same-same but different 🙂

Speak for yourself… a kilo is definitely more than 1% of me on a cx bike. One of the reasons I love cx riding.

[shuts up before she starts an iDave-BMI-what did you have for breakfast thread]