Without using a powermeter, any way to estimate average watts over a sort TT? I’ve checked out analyticcycling.com but there are a ton of variables to estimate that I have no idea about (frontal area, rolling resistance, etc.). I do a weekly 12 mile TT where I average around 24 mph. The course is rolling with a couple decent climbs. Anyone want to hazard a ballpark average amount of watts I’m putting out? Is it like 200? Maybe someone with a powertap can chime in with their avg watts over a similar course.

Here is some essential info:

Low position on a p2k (16cm saddle to bar drop), pretty small frontal area because I’m a twig
No aero helmet, but disc rear and 60mm front
Total weight of body, bike, equipment, about 160 lbs, 73 kgs

Thanks, I’m just curious most of all. I know my watts probably aren’t that great because I have a pretty low body weight, so I have less mass to move around.

First of all, I’m not a power expert by any means, but I would have to believe that if you’re averaging 24 mph you’re certainly generating more than 200 watts, especially if the course is undulating, as you say it is.

As far as estimating your watts, I ran across this article earlier today: http://le-grimpeur.net/blog/archives/15
The article contains a formula which, if accurate, will allow you to roughly calculate your power output on a climb. Obviously this doesn’t help you for your 12 mile TT, but perhaps you can find a suitable climb in your area to produce some numbers that you can play around with.

The formula is the weight of you and your equipment in kg (so 73 in your case) times 9.8 (downward acceleration due to gravity) times elevation gain in meters. Divide the result by the number of seconds it takes you to climb and you have a rough estimate of your wattage during the climb. The article also suggests adding 10% to the final number to account for air and rolling resistance, I don’t know how reasonable that is.

Since you already know how much you and your bike weigh, all you would need to know is the elevation change of your climb. There are a number of websites out there that should allow you to calculate this reasonably well. I would imagine that the formula is more accurate for a steeper climb, because you will be going slower and the effects of air resistance will be less significant.

Obviously, this is a roundabout way to calculate power and will only be able to give you a ballpark number, but it’s better than nothing. Perhaps some of the more fortunate members who own powermeters can give feedback on the accuracy of this method. Have fun.

Who knows for sure but definately way beyond 200 watts…I did a 14 mile bike leg of a tri last week and averaged 24.1 mph with an average watts of 259 and normalized power of 297 watts. if was flat, modest wind, with about 1.5 miles of slow, technical stuff. I have a very aero set-up.

I find that on the flats with limited wind I can average about 20-21 mph around 190-200 watts. I’m shooting for 22.5 mph at IMFL and figure I’ll need 225-235 watts…

You can get a crude guesstimate using formulas and I’m sure there are more than a few people on ST that could pin a number down within 5%. There are so many variables on an open road that anything other than a run on a dead flat road with no wind and your numbers will be off. Riding with a power meter is really an eye opening experience about how variable your output can be.

Just for reference, me + equipment = 163lbs. 20k flat TT, 199 avg watts gets me 23.2 mph. Last test done with P2C, Alps front, 808 rear, pneumo helmet. I’m definitely no power monster but do OK when the road tilts up.

The thing is estimated average watts don’t get you to the finish line and don’t mean diddly shit if you’re not going to train with a power meter.