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What's your avg speed on a 20k TT ?(12 posts)

What's your avg speed on a 20k TT ?jukosho
Aug 29, 2002 9:53 AM
I am entering my first ever race in 2 weeks, and wondering what a good avg speed for a Cat 5 20k TT would be. I know wind and terrain matter, just wanting some general guidelines. I avged 20mph on 20k without aero bars,etc and just don't want to place dead last.
Half an answer and a couple more ?sJakob
Aug 29, 2002 12:09 PM
For a 10 mile (roughly 16k) TT I average about 23-23.5 mph. It's a totally flat out and back course with minimal wind. That's without an aero bar. I'm in pretty average shape and my times are usually middle of the field.

Are you entering a TT race? You won't be dead last.

Is there a standard percentage gain for using aero bars? I mean, assuming your bike fits you well without aero bars, then you put aero bars on that fit you, and you're on a flat, relatively wind-free course, is it a 3% speed increase? Maybe 5%? Someone told me it was more like 10-15% and I just find that hard to believe.
Half an answer and a couple more ?sjukosho
Aug 29, 2002 12:47 PM
Yes it is a TT (20K). I am riding my same course tonite with my aero bars and will post the difference. Last time, w/o bars, I got:
12.24 miles, Avg Speed 20.0, Time 36.39

This was AFTER I got dropped from the group ride, so I had been going hard for about 18 miles. I expect that could cost me some time. Tonite I am shooting for ~35 mins. I have heard aero bars give a 1-3mph advantage. Based on only a 1mph gain, that would be 9 seconds/mile, thus 110 seconds on 20k.
1 mph gain way to muchtao
Aug 29, 2002 3:28 PM
I've seen a couple studies based on 40k TTs. One had the advantage at 30 seconds the other at nearly 60, one was by Burke. Of course it really depends on how much you reduce your drag but 1.5 seconds per k seems about the most you can hope for, or 30 seconds for your 20k.
TT bike vs. standardKerry
Aug 29, 2002 5:41 PM
I've had the opportunity to ride the same course a few times with a "semi" TT bike a standard road bike, and a road bike with aero bars. The TT bike was actually a crit bike (75 degree seat tube angle) with 36 bladed spoke front wheel, aero bars, and wheel cover in the back. I found this set up to be good for about 90 seconds in 10 miles. Putting an aero bar on a road bike was worth nothing for me. The reason being that my position was not good - I could tell that it was easier to pedal but I could not breath well (seat too far back, legs hitting chest). So aero bars can be a highly variable thing, depending on whether you can breath, how low you get, how close together your arms are, etc.
Power vs SpeedLeGrimper
Aug 29, 2002 9:27 PM
When you fit the bars to your bike you have to find the middle ground that will allow you to deliver your optimum power but also you need to be able to breath fully, be comfortable and be able to hold an aero posistion. Dont just slap them on an expect to go a few mph quicker.

Also I have never seen it posted but the trick to a fast time is a steady effort. I use a 7 heart beat window. For 20km you need to know your best average heart rate for the distance, say its 177 (out of a 191 max). Then set the alarms to 175 and 182 and stay in these limits. Going too high or too low will cost you time. Too low (ie less than 175) and wattage drops. Go too high and excess lactate for the effort will slow you up in the final leg. The best guys can sit in on 1 or 2 beats and hold the effort. Whether up hill or down, into the wind or tail make the numbers.

For your first time dont expect too much, there is more to it than meets the eye. Tell us all how you go.

Most important of course, have fun!

Le Grimp
TT resultsjukosho
Aug 30, 2002 5:54 AM
Well, I attempted my 20K TT ride with the aero bars. Unfortunately, there was a major head wind. I took off too fast, trying desperately to better my previous avg speed even tho there was wind. Needless to say, I burned up in just a few miles. Side started hurting, legs aching. One thing I did was find my LT tho. About 170 seems to be where my legs really fill with lactic acid. I seem to most effective at 160-165. I also agree about proper fit with aero bars. I have been fit for my bike (w/o bars), but just clamping these bars on myself is not the way to go. Had alot of neck pain and difficulty breathing. But I could still tell they helped about 1mph-1.5mph in the wind. Will try again on a less windy day to get a fair comparison.
TT resultsjukosho
Sep 9, 2002 5:21 AM
Did another 20k, this time with mild wind. Took me 35:30 and averaged 20.9. We will see this Sunday how I do in the field.
re: What's your avg speed on a 20k TT ?AjayM
Aug 30, 2002 7:03 AM
If you want to check out some good aero articles here are a couple of links,

http://www.cervelo.com/qa/article5.html
http://www.bicyclesports.com/index.html (got to the technical section).

The first link just kind of shows you some differences that some changes will make (like position, wheels, wind, etc). The second link will give you some ideas on achieving a good aero position. There is also a lot of wind tunnel testing of different products, etc.

Looking at some of the club TT's around here, on a 10k TT the times vary from 16 minutes for the fastest to 22 minutes for the slowest. I don't know the weather conditions on those days, but it would have been a flat course for sure.

Andrew
re: What's your avg speed on a 20k TT ?IcemanG17
Aug 30, 2002 8:21 PM
Well I haven't actualy tried a TT that long, but I would guess that an average speed of 20.0mph for a CAT5 should not be last place...probably won't win...but should be mid pack. Personally I only do short TT's...around 5K, just to measure fitness over the season (since thats the distance in Lance Armstrongs/Chris Carmichael's book...which states a 3 mile flat time trial of less than 8 minutes (male times) is considered good....the only time I tried it I got 8:23(which end up 21.6mph)...which I was happy with, but my HR was too low...should have been higher...Hopefully it will be faster next time:>) Figure a Pro could do it in less than 6 minutes!!
Iceman
Iceman
re: What's your avg speed on a 20k TT ?legs
Sep 2, 2002 2:06 PM
20 mph in 20k tt sounds a little off the pace and i am going to bet you will finish in the last third at that pace..
and i am willing to bet you can find 1 or 2 mph in there somewhere.... (either in your postion or gearing or by practicing a bunch of thirty-minute efforts at tempo).

a typical winning time would be at about 26-28 mph on a rolling hill course with a little breeze at your face).

best of luck to you....
re: What's your avg speed on a 20k TT ?DougSloan
Sep 3, 2002 5:58 AM
The harsh reality is that 20.0 mph is going to be very slow. While I'd rather make you feel good about it, I assume you really want an honest answer. I don't think I've seen people come in under 22 mph; there are many riders who can average 20 mph for 200 miles.

If you can, get the aerobars on immediately and get used to them before your race. I have found they can add 1 mph -- it's overwhelmingly the best improvement you can make to a bike for riding solo. Nothing else even comes close, not even a complete aero bike with aero wheels does as much good.

Doug