Not that it'll ever come close to applying to me, but was curious what Cavendish uses to hit 40mph in his sprints on the flats. In the videos on youtube, his cadence is actually quite reasonable for such an insane speed.

53-39 in the front. 11-23 in the back.

Spinning at 120rpm in the 53-12 will get you going 41.4mph on 700x23c tires.

I was looking at a previous thread on BF. Some guy timed it and said he was doing about 115rpm... So probably sprints in the 53-11 on a flat.

This was hashed out recently in the professional cycling forum, and although the thread completely blew apart, it had some useful information...

https://www.bikeforums.net/showthread...ts-and-Sprints

cavendish has said that he has been clocked at 76 km/h, pretty much about 47 mph.
https://www.youtube.com/watch?v=eO82Y...eature=channel
and if you watch the overhead shots, you can see the lead outs and then the jump at the end...the lead outs are going 40 mph and then you can see the jump in speed. 53x11 + spin fast!

Anybody can easily hit 40mph in a sprint. just sayin.

I haven't been able to 40 in years...so I'm not anybody.

max speed is not what makes pros, pro.

I'm guessing it's a 56 x 6.

Aren't you a CAD guy? You can't package 6 teeth on a cassette; the diameter is too small.

Has to be a 60 x 11.

DG

He rides a Scott. Enough said......

I think my man Liggett said Cavendish had a 54 on his big ring. All I remember is he had one step up.

He was explaining how most use 53, but Cavendish used the largest on the tour.

I thought that was someone else that had the 54.

Even if I could, I couldn't do it at the end of a stage.

incorrect

Channelling *****, or Neurosport ? (I get those 2 geniuses mixed up)

Cavendish has turned into the new Lance when it comes to Phil and Paul.

They were saying that Ciolek was using a 54, if I remember correctly.

It's an 11 with 5 teeth missing.

I heard it was a few gallons of high grade jet fuel. The above picture was taken outside the HTC bus at the TDF.

A BIG part of how he goes so fast is that he gets MUCH more aero/lower than any other sprinter. Watch him and he looks almost like he's descending while sprinting, he's so low on the bike. At those speeds, that's a HUGE difference.

Using Kreuzotter's algorithms, consider the following two scenarios:

(Both on flat ground, 2mph headwind, 15 lb bike, 160 lb rider, 70 inches tall, 1200 watts)

Hands on bar tops yields a speed of 34.5 mph.
Hands on the drops yields a speed of 39.8 mph.

Going that fast, aerodymanics makes a bigger difference than putting out more watts. Just moving your hands to the drops gives a 15.3% improvement. So if Thor, Pettachi and Cavendish all put out the SAME watts, Cavendish will go faster.

And here's the amazing thing, if he instead was as "un-aero" as the other riders but instead put out 15.3% more watts (1383.6 watts in this example), he'd only go 36.7 mph!! (Only a 6.3% gain) That's right, watts have a diminishing return against the wind.

That, and he certainly picked the right parents!

Correct.

I've hit 40 in my 52/12 but this wasn't an hour into my ride yet, so I doubt I can sprint that fast at the end of a road race. Plus I'm now equipped with a 52/14, and the max I've gone was about 37...again it was early in my ride.

And 40mph isn't a sprint yet for a pro, unless maybe there is a slight incline or a headwind. I think Mark Cavendish crashed (Stage 4, Tour de Suisse 2010) at around 50mph because that's what i remember hearing from the commentary.

And if you still need proof, take a look a Tyler Farrar's sprint.

Note: 78km/h= 48.5 mp/h

Ah, but that wouldn't change the ratio.

The gear ratios on a chain (or any gear for that matter) aren't actually a function of the teeth but rather of the diameter of the gear. Because the teeth are on a fixed pitch changing the number of teeth and keeping the spacing equal has the effect of changing the diameter, but it's the diameter that matters from a mechanical advantage point of view.

If you take an existing gear and break off teeth, the diameter remains the same and therefore so does the gear ratio.

The diameter of the axle and the axle support bearing is the limiting factor on how small the rear cog can get. At current chain pitch, that corresponds to 11 teeth.

DG

I can't believe I read 8 pages of that without having a satisfying conclusion.

He was banned, so there won't be any conclusion...