Do the track bikes used by Chris Hoy and Vicky Pendelton have a minimum weight limit? Is Chris's bike heavier? If Chris rode Vicky's bike would it crumple under the weight and power?

I know there are minimum weights for road racing but I was thinking about the Colin Chapman idea that if your vehicle does not fall apart just after crossing the line its stronger thus heavier than it needs to be – and Chris Hoy must be a significant % heavier and more powerful than Victoria Pendleton so from that logic her bike should be a lot lighter and if Chris rode her bike it should just collapse under him

I don't think the weight is so important when you're riding around a track, but I'd still be interested to know if the 6.8kg weight limit is imposed on track bikes.

I'm pretty sure the UCI rules apply to all track, road and cyclocross bikes used in their races.

It's no different to road cycling. Emma Pooley is only 7st 10lbs or something and has to ride a bike with the same weight limit as Jens Voight who's 12st something (about the heaviest pro I can think of at the moment!).

I wonder how much power / torque Chris Hoy puts out?

I would think that the stiffer the bike the better the transfer of power, regardless of the actual power levels involved. I don't think weight makes any difference in some of the longer events, but stiffness would probably.

Acceleration is affected by power to weight and both of them do events where acceleration is critical

The weight limit does apply, and sprinters usualy use different bikes (with super stiff round tubes) to longer distance riders (more like TT frames with 120mm rear ends).

To do 1km, at sea level, in 50seconds (flying start) takes about 650W of power, although I guess his peak power is probably towards the end of his acceleration (once he's reached 60-70rpm) where he's traveling some speed, but still able to keep the power going through whatever gear he's in. (power = force*speed).

Back of an envelope calc I recon his peak power is about 2000W!!!

in other words he can boil enough water for four mugs of tea in about three minutes?

2KW is about 3 bhp. that's fairly impressive. I seem to remember one of the motorcycle magazines putting one of their staff who was a keen MTBer on a dyno and getting 1.2 bhp.

Torque of course will be massive – like a 2 l diesel car as its power / revs and with a rev in the 70- 100 rpm range rather than thousands

I think Mark Cavendish has a peak power output of about 1800w – so Hoy must be 2000w at least…

For anyone who has ridden using a power meter, that's scary!!!

Hoy's measured peak power is around 2400 watts.

the Colin Chapman idea that if your vehicle does not fall apart just after crossing the line its stronger thus heavier

That wasn't ever really Colin Chapman's idea. Well it sort of was for things like engines/brakes/etc which wear (eg the engine should ideally blow as you cross the line, the brakes blow apart, etc) but not for the things that don't – eg suspension, the body, etc.

I was umming and ahhing arround 2500W, but its just seemed incredible, apparently my calculation was playing it safe!

n.b. in comparison the average person can output 400W for a few seconds (measured by sprinting up a 45deg flight of stairs)

Yea peak torque will be as he leaves the start line guestimate about 300n/m at the crank (effectively yout doing a leg press), but theres little power here as he's barely moving. Peak power I guessed would come as he was gettign upto speed but wasn't spining out, i.e. was still outputting near the maximum torque but was moving at a fair pace.

This is not a spoon – the dyno graph I saw form a keen cyclist had a torque curve that went virtually straight to maximum and stayed there until 60 / 70 rpm when it dropped of fairly quickly.

Those are totally mad numbers for Hoy – but believeable.

The bikes are subject to the same weight limit as road bikes, ie 6.8kg. You're also not allowed moveable weights any more – all the weight must be structural with no lead weights down the seattube!

Bikes are custom built to the athlete, the sprint ones are heavier than the pursuit bikes cos they use thicker carbon for stiffness. All the Team GB riders use PowerCranks, there's a room full of them at Manchester Velodrome, each athlete has their own: one for road, one for track. The wheel rack there holds about £500,000 of Mavic wheels!

The sprint wheels are custom built by Mavic, normal ones they found had too much flex in them! I've seen regular 32h track wheels break under the strain of sprints, you can sometimes see wheels of more normal track bikes flexing under a heavy rider. Lockrings are compulsory for sprints, it's not unknown for riders to strip threads and it stops the cog flying off.

There's a whole raft of technical rules and regs re bike weights, measurements and angles that the UCI stipulate, in fact some of the Team GB track bikes have had to be changed recently to accommodate this.

Oh and in answer to the original question, no Vicky's bike would stand up fine to Chris riding it, cos she puts out somewhere in the region of 1800 – 2000W!

Ta chaps

no Vicky's bike would stand up fine to Chris riding it, cos she puts out somewhere in the region of 1800 – 2000W!

Indeed – she was pretty rapid on Tuesday night on the women's 500m time trial (though got notably fewer cheers than my clubmate doing the Kilo).

What I find interesting about the BC bikes is that although they are incredibly strong in "normal" use, they snap a lot more easily than bikes on the open market when crashed. Even the flyweights shap them! (Kennaugh in the worlds Madison for example)

a bike coming apart in a crash really doesn't depend on whether the rider is big or not. Seen lots of 'normal' track bikes disintegrate..

FWIW I can do about 1400W peak, without having ever trained for it. The average person (man?) would easily trash 400W on a bike for a few seconds. My guess is about 1000W for a generally capable normal bloke.

Me too Andy, but I don't think I've ever seen a BC bike survive a crash!

Me too Andy, but I don't think I've ever seen a BC bike survive a crash!
Plenty do…eg Lizzie Armitstead seemed to do OK when she crashed in the scratch race at the Worlds…?

The bikes are amazingly tough, they'll survive fairly hefty impacts. Most are OK, it's very rare for carbon to fail spectacularly. If it does it's a major PITA cos the track needs to be meticulously swept to get all the carbon fragments off it, they can easily cause punctures and more crashes.

you got me there! Must be frontal impacts when the forks come flying off

carbon bits….

wow, that keirin race is bloody exciting. why don't they show more track racing on TV? beats the pants off F1!