Is there a max gear ratio in UCI Road Events ie TDF

[hdcsb]

Is there a max gear ratio (ie in gear inches or whatever) for UCI Road Events? I figure there must be be as they generally free wheel above 85kmph or so and tend to hit no more than roughly 120kmph on the most extreme descents. For guys capable of dishing out over 400 watts you'd think in the right gear in the right place, they could smash that.

[trek52]

No I dont believe their is, I think aero dynamuics take over and 100km/h needs more than 400w to go to 105km/h. the faster you go the more aero drag meaning more watts to increase speed.

[hdcsb]

Makes sense, air resistance does become exponentially larger the faster you go, but when you hear of Fred Rompelberg hitting 268.831kmph on flat land behind a drag car, TDF speeds seem way slow. Granted the drag car causes minimal air resistance and is possibly sucking him along? Still, I'd tend to think all the freewheeling means UCI cyclists can go faster for sure.

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[JdM]

Iso and tend to hit no more than roughly 120kmph on the most extreme descents. For guys capable of dishing out over 400 watts you'd think in the right gear in the right place, they could smash that.

Perhaps they don't want to die?

[BenGr]

Makes sense, air resistance does become exponentially larger the faster you go, but when you hear of Fred Rompelberg hitting 268.831kmph on flat land behind a drag car, TDF speeds seem way slow. Granted the drag car causes minimal air resistance and is possibly sucking him along? Still, I'd tend to think all the freewheeling means UCI cyclists can go faster for sure.

http://fredrompelberg.com/EN/world-record" onclick="window.open(this.href);return false;

Take a descent at their speed and come back.

I'd also recommend you take a look at the power required to exceed the various forces on a bike. Roughly put above 20kph drag is the dominant factor, and drag increases to the square of velocity.

Racing is about crossing the line first, not having the highest max speed. Whilst both may occur at the same time, many cyclists would trade descent speed for accent speed.

[hdcsb]

Take a descent at their speed and come back.

I'd also recommend you take a look at the power required to exceed the various forces on a bike. Roughly put above 20kph drag is the dominant factor, and drag increases to the square of velocity.

Racing is about crossing the line first, not having the highest max speed. Whilst both may occur at the same time, many cyclists would trade descent speed for accent speed.

Hey, I have huge respect for anyone willing to do those speeds, with my current ability anything over 80kmph is still a big unknown . A big reason why I ask the question is because there's probably someone here that has the experience (or at least UCI knowledge) to know.

From what I've seen on tele there's usually at least one descent finish every Grand Tour and even then, there's a fair amount of freewheeling. It makes me wonder.

[Uncle Just]

Is there a max gear ratio (ie in gear inches or whatever) for UCI Road Events? I figure there must be be as they generally free wheel above 85kmph or so and tend to hit no more than roughly 120kmph on the most extreme descents. For guys capable of dishing out over 400 watts you'd think in the right gear in the right place, they could smash that.

53 x 11 is the usual max on road stages. No official max gear is prescribed by the UCI it just depends on the rider's ability to handle the right gear for the course without disadvantaging him for any climbs. The idea is to get up to high speed then get into the right tuck to increase the aero effect. TTing will bring out the 54/56 ring for those strong enough to push that monster.

Never seen a verifiable 120km/hr descent recorded. Plenty of 100-110km/hrs but the real good descenders in the past such as Yates or Salvodelli for example were pre sophisticated GPS devices and while some say Kelly reached a 110+ on one descent it can't be verified. IME anything over 90 is fast and best left to the gung ho and capable.

[ldrcycles]

From what I've seen on tele there's usually at least one descent finish every Grand Tour and even then, there's a fair amount of freewheeling. It makes me wonder.

Easy one, the person who wins is the one who puts in the least effort until the finish. Especially in a Grand Tour, conserving energy is critical.

[Strawburger]

From what I've seen on tele there's usually at least one descent finish every Grand Tour and even then, there's a fair amount of freewheeling. It makes me wonder.

Easy one, the person who wins is the one who puts in the least effort until the finish. Especially in a Grand Tour, conserving energy is critical.

Bingo!

Also, TTers are known to use 56 rings on the front for flat stages.

[MattyK]

TTers are known to use 56 rings on the front for flat stages.

This I believe is so they can sit in the middle of the rear cluster for maximum driveline efficiency.

As for the road racers, at 100 kmh downhill they would be facing a few kW of drag force. Their human effort of an extra 400W isn't going to add much top speed, as per the cubic law quoted above. So there's not much benefit to providing the gearing to help with this, especially if it takes away from other factors like gearing for flat or uphills or weight or shift quality.

[danny the boy]

Descending at those speeds has little to do with watts or gearing. Try sitting on the top tube next time you go down you local hill.

[rogan]

53 x 11 is the usual max on road stages. No official max gear is prescribed by the UCI it just depends on the rider's ability to handle the right gear for the course without disadvantaging him for any climbs. The idea is to get up to high speed then get into the right tuck to increase the aero effect. TTing will bring out the 54/56 ring for those strong enough to push that monster.

Never seen a verifiable 120km/hr descent recorded. Plenty of 100-110km/hrs but the real good descenders in the past such as Yates or Salvodelli for example were pre sophisticated GPS devices and while some say Kelly reached a 110+ on one descent it can't be verified. IME anything over 90 is fast and best left to the gung ho and capable.

FWIW, Gerro says the fastest he has done on a bike is 117 km/h [source - after dinner speech]. I would have thought guys like Cancellara and Sagan might be even faster. On steep straight downhills, many of us forum warriors of mixed abilities have done over 90, and some well over. I've heard unverified suggestions of over 100 being reached coming off Tawonga Gap during 3 Peaks, and even down New Line Rd heading south from Dural (in northern Sydney, if you know that area). But pros who know what they are doing, with some kind of draft happening, in a serious race, on REAL mountain descents? Significantly faster, I would have thought.

[g-boaf]

One of the Belkin riders (iirc) in the TDF clocked 137km/h on one descent.

I've done some pretty high speeds downhill myself, at 80km/h plus, it feels less about power and more about aero efficiency. Pedalling doesn't feel like it makes much difference, but tucking down (on the top tube) feels like it makes a huge difference - the speed increase is noticeable. That said, it's quite pointless for us to be doing that, what do you get in return for it?

[jules21]

I've heard unverified suggestions of over 100 being reached coming off Tawonga Gap during 3 Peaks,

I doubt it. top of 65 km/h for me and I'm not riding the brakes. there aren't many high speed points in the Vic Alps - probably the fastest is down the pinches on Hotham's upper slopes - Diamantina and CRB and I only get around 80 km/h (no brakes).

I can get 85-90 clicks down Foote St in Templestowe, Melbourne - steep and straight. the mountains aren't straight enough.

[cyclotaur]

I'll go with what others know with respect to regs etc and support the notion that high speed descending is all about aero and technique.

My fastest ever 'believable' recorded speed is low 80s down that long straight hill outside Marysville just before the turn into Acheron Way. That was on a CX bike with only a 46 big ring so I was coasting over about 50kph ...

I have my doubts about some speeds derived from GPS/Garmin/Strava as I just know they're dodgy - otherwise I'd be claiming several 100+ speeds on winding descents. No way they're correct.

[jules21]

I have my doubts about some speeds derived from GPS/Garmin/Strava as I just know they're dodgy - otherwise I'd be claiming several 100+ speeds on winding descents. No way they're correct.

the speeds shown by Strava etc. appear to be post-processed speeds. I can't say for sure, but I agree that the real time speeds displayed on your device are often way off. but once they're uploaded to my computer, Strava etc. seems to do some refining and they come out as more believable - and different to what was displayed during the ride.

[GAV!N]

From what I've seen on tele there's usually at least one descent finish every Grand Tour and even then, there's a fair amount of freewheeling. It makes me wonder.

Easy one, the person who wins is the one who puts in the least effort until the finish. Especially in a Grand Tour, conserving energy is critical.

Bingo!

Also, TTers are known to use 56 rings on the front for flat stages.

I think Tony Martin even had a 58 for the TT worlds last year or the year before didn't he?

[Cheesewheel]

One of the Belkin riders (iirc) in the TDF clocked 137km/h on one descent.

I've done some pretty high speeds downhill myself, at 80km/h plus, it feels less about power and more about aero efficiency. Pedalling doesn't feel like it makes much difference, but tucking down (on the top tube) feels like it makes a huge difference - the speed increase is noticeable. That said, it's quite pointless for us to be doing that, what do you get in return for it?

Potential gravel rash till Christmas?

[ldrcycles]

One of the Belkin riders (iirc) in the TDF clocked 137km/h on one descent.

I've done some pretty high speeds downhill myself, at 80km/h plus, it feels less about power and more about aero efficiency. Pedalling doesn't feel like it makes much difference, but tucking down (on the top tube) feels like it makes a huge difference - the speed increase is noticeable. That said, it's quite pointless for us to be doing that, what do you get in return for it?

Potential gravel rash till Christmas?

I managed this at only 35, so 100+ could be very nasty indeed...

[g-boaf]

One of the Belkin riders (iirc) in the TDF clocked 137km/h on one descent.

I've done some pretty high speeds downhill myself, at 80km/h plus, it feels less about power and more about aero efficiency. Pedalling doesn't feel like it makes much difference, but tucking down (on the top tube) feels like it makes a huge difference - the speed increase is noticeable. That said, it's quite pointless for us to be doing that, what do you get in return for it?

Potential gravel rash till Christmas?

I managed this at only 35, so 100+ could be very nasty indeed...

I've still got scarring on my leg from one at 35km/h. So no, tucking down on the top tube, while I've done it a few times - no thanks. I've seen what can happen in a high speed off at 60+km/h, and that wasn't too pretty. Even seen someone get a broken collarbone at 20km/h, which was just down to some inexperience and truly bad luck.

I bet that gravel rash when they cleaned it up killed like nothing else!

[jules21]

that is a serious flesh pizza!

[TheWall]

^^^ [FEARFUL FACE] Seriously not looking fwd to my 1st crash...

[ldrcycles]

I bet that gravel rash when they cleaned it up killed like nothing else!

Oh yea it was a barrel of laughs. Got back on the bike the same day though .

[__PG__]

I've heard unverified suggestions of over 100 being reached coming off Tawonga Gap during 3 Peaks,

I doubt it. top of 65 km/h for me and I'm not riding the brakes. there aren't many high speed points in the Vic Alps - probably the fastest is down the pinches on Hotham's upper slopes - Diamantina and CRB and I only get around 80 km/h (no brakes).

I can get 85-90 clicks down Foote St in Templestowe, Melbourne - steep and straight. the mountains aren't straight enough.

Agree w.r.t Tawonga Gap. It's too windy and not steep enough.

I hit 78.5 on Sunday b/w Dinner Plain and Omeo. I think that's a record for me. Dead straight road, perfect visibility and fairly steep.

[queequeg]

Strava shows that I did 87.1km/h down one or the descents in the Fitz Epic. I think it was Honeysuckle, and I was hanging on for dear life, tucked in behind my riding partner.

Near my house is also the New Line Rd descent where it has become possible to get into the mid-80's with no effort (thanks to the hotmix and realignment). I reckon an early morning run down the hill and getting into the 90's should be easy.