Re: Compact vs Standard double for sprinting
Posted: Wed Aug 10, 2011 3:49 pm
Cadence and Speed for 23-622 clincher, inflated to 120psi, diameter 209mm with rider and 1/2 filled drink bottle.
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Damn, there goes my excuse for getting rolled in the finish sprint there last Sunday in 52 x 13! Bugger bugger bugger!="Alex Simmons/RSTI've won A grade on the Eastern Creek downhill sprint and was in the 53x13.
Is it? I've turned up to races and TTs with a $799 (new price) Sora/2200 roadie or an old $600 TT bike, Katmandu jersey, MTB shoes and cheap Cell knicks, and never had a single elitist remark. All the club and ATTA events have been very welcoming and everyone has been very friendly.fenn_paddler wrote:Compact criticism is just another form of elitism. Which is common in road cycling...
how fast, what cadence?Alex Simmons/RST wrote:I've won A grade on the Eastern Creek downhill sprint and was in the 53x13.
Said rider deserved to lose the sprint for over estimating his hydration requirement!winstonw wrote:Cadence and Speed for 23-622 clincher, inflated to 120psi, diameter 209mm with rider and 1/2 filled drink bottle
Or deserved to lose the sprint for not drinking all of his hydration requirement, which is probably more common.sogood wrote:Said rider deserved to lose the sprint for over estimating his hydration requirement!
That assumes,winstonw wrote:And if he drank the half bottle 10-15 minutes pre sprint, the weight on the tires in the sprint would be close to what it was by not drinking it.
Is there are typo in there somewhere? If not then maybe it's time to replace the 20 inch wheels.ft_critical wrote:I have raced the same two courses on both a 12-25 and an 11-23 on 172.5 cranks and a 39/53 Chainring set. Both times I raced the 12 I ran out of gearing. At West Head, solo, chasing the break into Salvation Creek and a second time at Eastern Creek in the sprint finish (68kmh, 158rpm is my best sprint here on a 11-23 by way of reference.)
Quite possibly, but when you aren't exactly smashing yourself much before the sprint, that's no surprise. That was my point about the pros sprint power. Per se it's not that spectacular. But after smashing yourself, it is damn fine work.ft_critical wrote:The B and sometime C grade sprints are faster than A grade in my experience.
Actually I was wrong. I was in the 53x14, not the 13.ft_critical wrote:how fast, what cadence?Alex Simmons/RST wrote:I've won A grade on the Eastern Creek downhill sprint and was in the 53x13.
No typo sblack, but fair to call it out. This is from my notes, and at the time I was only using a PRO wireless computer. So the top speed is accurate, but I don't know when that 158 was printed. Whilst not a lie, it was just the top rpm on the PRO computer for that day. But owing to your keen eye I checked two recent Garmin sprints, I don't know the gears but not more than a 12, probably a 13, but at 100rpm I was at 55, and at 110 at 62, both flat. And, I don't think I can spin faster than about 130 anyway. So let's call 158rpm bull. Thanks for keeping it honest.sblack wrote:Is there are typo in there somewhere? If not then maybe it's time to replace the 20 inch wheels.ft_critical wrote:I have raced the same two courses on both a 12-25 and an 11-23 on 172.5 cranks and a 39/53 Chainring set. Both times I raced the 12 I ran out of gearing. At West Head, solo, chasing the break into Salvation Creek and a second time at Eastern Creek in the sprint finish (68kmh, 158rpm is my best sprint here on a 11-23 by way of reference.)
Thanks ft-critical, those numbers make better sense, pretty much right for a 53x12 combo. What data do you have on the times you felt you'd run out of gearing with the 53x12? That'd give better details on what cadence you feel you spin out at and maybe provide a better estimation of how you'd go with a 50x11 (bringing it all back to the 53 vs 50 originally asked). From what you provided so far it would seam it's somewhere in the 120-130 range, where the 53x12 combo may not allow you to hit your 68 km/h sprint but a 50x11 could. It would be interesting to see how you'd go on those same courses with a 50x11.ft_critical wrote:No typo sblack, but fair to call it out. This is from my notes, and at the time I was only using a PRO wireless computer. So the top speed is accurate, but I don't know when that 158 was printed. Whilst not a lie, it was just the top rpm on the PRO computer for that day. But owing to your keen eye I checked two recent Garmin sprints, I don't know the gears but not more than a 12, probably a 13, but at 100rpm I was at 55, and at 110 at 62, both flat. And, I don't think I can spin faster than about 130 anyway. So let's call 158rpm bull. Thanks for keeping it honest.sblack wrote:Is there are typo in there somewhere? If not then maybe it's time to replace the 20 inch wheels.ft_critical wrote:I have raced the same two courses on both a 12-25 and an 11-23 on 172.5 cranks and a 39/53 Chainring set. Both times I raced the 12 I ran out of gearing. At West Head, solo, chasing the break into Salvation Creek and a second time at Eastern Creek in the sprint finish (68kmh, 158rpm is my best sprint here on a 11-23 by way of reference.)
sogood wrote:That assumes,
1) There's no water loss during the drinking phase, which we know happens regularly.
ok let's presume 30mls makes its way into the jersey but that's still weight on the tyres, and another 30ml gets tossed with the bottle.
2) The rate of insensible fluid loss is identical between the two hydration states of said rider, which may not be true.
it's possible he sweats more in the underhydrated state, considering he will be shunting heat less effectively. Hard to say which state retains the greater weight.
3) A fuller stomach will alter the aero profile of said rider, affecting the sprint outcome.
any aero disadvantage of a fuller stomach will be offset by having tossed his water bottle.
4) Risk of stomach upset by that 1/2 bottle of water.
true. ideally if sweat rate was 1L/hr, 300mls should be taken in over 20 minutes
5) Weight on tyre is a determinant of sprint success.
I've never witnessed a constant speed sprint, so I'll presume acceleration, hence weight, matters.
Still a good try though!winstonw wrote:...too hard.
OK, after giving my brain a restsogood wrote: Still a good try though!
Of all things, cadence is the easiest thing to measure on a bike, so you have to wonder about whatever is hooked up to those bikes.mikesbytes wrote:Anyway the point being that it makes me wonder about the accuracy of bike computers.
Don't need to, speed and cadence tells you what gear you are in. You can plot it if you like.mikesbytes wrote:Alex, some questions;
1. You corrected yourself to saying you were using the 14 in the A grade sprint, do you keep data on your gears? If I remember correctly there was a tail wind down the straight.
It's pretty common finding in the science studying maximal power development. We are talking very short range power here. Here's an item that might be of interest:mikesbytes wrote:2. You have noted that max power comes out in the 130 - 140 range, have you got any more info on this? I'm also interested in this figure from a training viewpoint
We are talking short range maximal power.winstonw wrote:Regarding max power occurring around 130-140, my googling says TdF sprints are commonly around 110-125.
As Alex says, maybe they are just too shagged after 200+km.
And is anyone efficient doing 130-140 out of the saddle?