So… serious question. Why is virtually every member of the Pro Tour peloton on tubs? They'd go quicker on clinchers, they're at the weight limit anyway, is it just the improved handling when you puncture?

I am indeed on WW, although I find it all very anal and frequented by people with too much money and not a clue about what's going on! See that 18lb Mojo on the MTB forum for a cracking example…

Why not a bit of thread drift? If you're up for trying to understand I'll have another go.

Pre-stressed concrete basically consists of concrete with steel bars going through the middle of it. Now most concrete has steel bars in for reinforcement, but in the case of pre-stressed they then put great big wahsers and nuts on the ends of the steel bars and tighten. This results in the steel bars going into tension and the concrete going into compression. What this means is that when the concrete gets a bending load (as in when it is used to make a bridge), rather than the bottom of the beam going into tension, the compression in it is just reduced. However from an engineering forces point of view you can consider the pre-stressed beam to be one homogeneous whole and the bottom of the beam to be in tension which the concrete beam is supporting.

Got that so far? Well a bicycle wheel spoke works in a similar, but opposite way. Obviously a steel spoke can't support any compression force as it will simply buckle (not to mention that the nipple isn't supported). However by pre-stressing the wheel by tensioning the spokes a spoke can then support a superposed compression force, which is as far as the spoke is concerned a decrease in tension. What you have to get your head around here is the difference between considering the wheel as a whole, in which case the spoke takes a compression force due to the pre-stressing, and considering the spoke in isolation, in which case the "compression" is simply a decrease in tension. You might think we're simply arguing semantics here, but this is important, as the hub isn't supported by the top spokes having increased tension, but by the bottom spokes having decreased tension, which can be correctly considered as a compression force.

I have a feeling that will still leave you confused – I'll try and think of a better way to put it. One of the problems with this is that I don't think Jobst explains this very well, though to be fair to him it is a difficult concept to explain (and I've probably done no better).

Very, very good question, njee. Not sure of the answer – partly sponsorship, partly the ability to ride on a flat (eg Olano in the '95 World Champs – if he'd been on clinchers he'd probably not have won). It's plausible they could use hard track glue, though I suspect not given that does have it's disadvantages even though they get a spare wheel if they puncture. I do remember one TdF stage a few years ago though which was a downhill finish in the wet where the winner got away on the technical downhill, and he was definitely using Michelin clinchers.

I know what you mean about ww – I rarely go on the MTB forum nowadays as that is what you get (in any case I don't have the money to "improve" my current bike at all, so it's not very interesting to me any more). However the road forum has some of the most knowledgeable people you'll find on a cycling forum anywhere – provided you can sort the wheat from the chaff you can get some very good advice, and you get some really interesting* technical discussions on there.

*interesting to a sad engineer like me

cheers aracer I think I get that (you've done a way better job than JB)

But…when loaded the bottom spokes do indeed have decreased tension, however the other spokes must have increased tension to balance that surely? Not sure if this makes any difference to the concept tho.

A few summers back whilst waiting for my mate to pick me up from work, I watched a roadie attempt and struggle to fix a puncture in a tub. After about 25 mins of faff, lots of swearing, dust and bits of grass stuck to the mess and stickiness that was the cement on the tub and rim, he gave up and called his misses to pick him up.
This proves that clinchers are faster as he would have been on his way in 5 mins or so with a clincher…

twohats that is excellent proof of:

Incompetent folk do ride bikes
one story alone can be pretty meaningless

Swapping a tub takes no longer than a tube