Trying to correlate my trainer’s resistance to road speed. Does anyone know the average relation between power and speed on the roads for an IM? I’ve read somewhere that a 6hr ride will be around 200 watts for the 112 miles?
Thanks everyone!
I’d say 6hr/200w is a bit high based on my experience. My last IM earlier this year results were 5:40 at 173w. My un-sciencetific guess, 200w=5:20. There are really too many variables to say (x)watts will correlate to (y) time at (z) distance.
Maybe someone a lot smarter than me will chime in.
Seems way too high for me - I used a tacx trainer for a 3 hr steady ride trying to hold 200w after. After 3 hours at about 197 average I couldn’t walk a straight line and was toast for 2 days. About a month later I rode 5:05 at Taupo.
Another of the hardest workouts I did on the trainer was 10 x 5 mins at 260 watts followed by 1 min recovery. This was a total death session about 3 weeks out from an Ironman - unless my trainer is way out of calibration (I hope so as my watt output seems feeble compared to others figures that I hear of!) then I think averaging 200w depending on external factors would see you off the bike in way under six hours - possibly sub 5:20 in good conditions.
Correction: after 3 hours on the trainer your brain was fried, and that’s why you weren’t able to walk in a straight line.
Yhea, its weird, when I have (had) a big race coming up training in no mater what form was never boring - I would quite happily sit in the garage, no music, no tv and ride for 3 hrs without thinking twice about it.
Half an hour of that now would be like psychological torture - thats motivation I guess and part of the reason that I am “retired” (for the moment!)
P.S. Love the quote from Bordin
Why did you retire? Are you a pro/former pro?
Pro? - don’t think I’ll be making any dough with a 5:05 bike split!
Really only wanted to do 1 Ironman but was a bit better at it than I thought I’d be so ended up doing a couple more finishing with Kona.
To go Ironman again I would want to be able to perform better than I had in the past and just don’t have the time to be able to grind out 20 - 40 hr training weeks.
Maybe I’ll go play golf.
Well, a 5:05 bike split is still downright impressive!
Thanks for the “power” advice.
What do you weigh and how hilly is the course? I averaged 201W at IMNZ, and weighed in at about 86Kg (190 lbs). I had to make a mechanical stop, but taking that out (was about 5 min) I was right around 6:00 even. On the other hand, Fernanda Keller averaged something like 177W and IMH and had a split in the 5:20 range.
I don’t think enough is made of the difference weight will make regarding power needed for xxx time. It not only bites you on the hills in a very big way, you are also likely to be less aerodynamic. Try riding in a paceline behind a big guy and a small guy and you can tell a lot of difference.
1 Like
The problem with Tacx Trainers is that they don’t Calibrate… they are only relative to each time you sit on them, not to themselves or other power meters, they are frustrating that way.
Trev
I’m just starting to monitor power but for what its worth (FWIW riding) a commuter bike stop and go and just noodling along at times I generated this file…
http://www.angelfire.com/retro/355_rider/pics/power/tt.com.93.1a.jpg
I am planning on riding the powertap for kicks during some races in 2005.
I’m light, around 144 lbs (65kg). I’m going to do IMCDA next june…I think the course is moderate, not TOO hilly but not very flat either.
I’m hoping to average around 19 mph.
ANd I definately agree that weight plays a big part on the hills.
While I’m still curious about how my power and speed compare to others, I’ve ge found comparisons difficult to do. Even for myself, my Computrainer and my Ergomo differ by about 20W.
However, for IMFL last week, my bike results were:
5:33:53 20.13 mph ; 32.4 km/h
193W average ; 202W normalized
HR: 147bpm average
Cadence: 75rpm average
Weight: 186 lbs
Cheers,
Rob
Weight and Aerodynamics play a big role. Also, when you utilize additional power, etc. Lots of factors. I did IMFL last week as well. I weigh 165, 6 feet tall. I rode very steady, with very few spikes…
Averaged 183 watts, 5:30 bike, 20.4 mph…
AVG HR of about 143. I’m 36
Basically, I rode the first 40 or so miles easy, at about 165-170 watts
After that, picked it up a bit, to around 195 watts or so, with some 200w riding. For the hills ( I use that word loosely), I capped wattage at about 225 or so…
200W average, with a reasonably good aero profile (frontal area of .54m^2), will get you 5:00 (10m/sec) on a flat, windless course. Go to analyticcycling.com and plug in some numbers. You may not be able to hold such an aero position for 5 hours, though.
While I’m still curious about how my power and speed compare to others, I’ve ge found comparisons difficult to do. Even for myself, my Computrainer and my Ergomo differ by about 20W.
However, for IMFL last week, my bike results were:
5:33:53 20.13 mph ; 32.4 km/h
193W average ; 202W normalized
HR: 147bpm average
Cadence: 75rpm average
Weight: 186 lbs
Cheers,
Rob
These are right around what many people experience on a flat course. However, it is quite possible to ride around 5:15 or even 5:05 on that wattage. It would take a smaller person (say under 5’8" and 155 pounds) riding in a relatively aggressive aero position. I’ve seen power files on rolling courses (CDA) at 200 watts going 5:15. I know a guy that rode under 5:10 at Brazil on 185 watts average/205 normalized.
I’m 6’ 158lbs and I can hold a very steady 22 mph on 200 watts (not that I can do 200 watts in an IM; I’m more like a 185 watt rider).
I think it is quite possible to ride Florida under 5 hours on 200 watts. A small-ish person on a very slick bike setup can do that.
Don’t forget the aerodynamics. Some may need 200 to go 5:00 and others, less aero and heavier may need 250 to go 5:00. There are too many unknown variables to predict your time based simply on power.
also keep in mind that when your muscles contract they produce energy, much of which is lost in heat. It’s therefore crucial to drink plenty and avoid dehydration. Although you might produce an equal number of watts, inside riding doesn’t give you the cooling effect of the wind. This might be an additional reason you felt toast after it.
Good point, you should have seen the lake of sweat under the bike when I had finished!
Best of all it was my mates garage and his wife had to clean it up as I was too tired… or so I claimed. No dinner invite for me for a while.
I’ve done 4 IM races and not once have I considered that I put out ANY power! 
certainly not enough power.