Power loss up Cols

ravenvrider

I have previously posted about my planned ride up the iconic Alpe'd'Huez to coincide with breaking my back exactly 2 years ago and my hope to do the climb in less than an hour just to make my task ...er interesting oh and being 52 didn't help. I did the climb a week ago so thought I would update here with some interesting info for anyone attempting a similar attempt.

Just to be clear i am a stats and numbers man so like to be able to quantify examine and rationalise my rides. I started training in ernest for my climb 4 months ago, I was in reasonable shape and started my 4 month schedule with a 20 minute wattbike FTP Test to get a baseline, the result was 263 watts, my weight was 146lbs (66.3kg) giving a w/kg 3.96 my coach gave me a training plan based on my daily commute plus 3 weekly wattbike sessions and a 2 hour Sunday ride.

In short over the 4 months my 20 minute wattbike FTP went up to 287 watts my weight went down to 139lbs (63.1kg) giving me w/kg 4.54...now take 5% off to get my hour FTP and you get 272 watts and w/kg of 4.32 now there is a really good and accurate graph http://alex-cycle.blogspot.co.uk/2011/07/lalpe-dhuez-one-for-mortals.html online that gives expected times up the Alpe based on your w/kg, for my 4.3 I was expecting to climb the Alpe in around 54 minutes which I was very happy with.

I rode the Alpe the second day I was there, the weather was good and I felt strong, I got into it immediately and took my hr up to my threshold (176bpm) and held it there for most of the climb going up to 180 ish on a few steeper ramps then sprinting the final straight taking it up to 187, my av hr was 178 for the climb so I was clearly on it all the way up, funny thing though my legs never really felt pushed which was clearly shown by my ability to sprint flat out from a long way out after an hours climb at threshold.

I completed the climb bottom to tourist office in 58.17 and to the Tour de France finish in 1.03.15 which is the one I was going for and the graph was based on.....so frankly I was very disappointed being 10 minutes off my expected time. I spent a lot of time researching afterwards and found something that I had completely overlooked and made perfect sense. I had totally misjudged the effect of altitude on my power. At the Alpes height (1860m 6,100ft) as a unacclimitised rider I would lose up to 11% of my power http://alex-cycle.blogspot.co.uk/2014/12/wm2-altitude-and-hour-record-part-ii.html http://www.joefrielsblog.com/2010/09/altitude-and-aerobic-performance.html ....I expected some loss but nowhere near that, 11% brought my achievable power down to 242watts which better explains my time and also why my legs did not feel pushed.....so the moral to this story....if you are planning to attack any large Cols do not forget about your power loss at altitude.... like I did.

fastandfurry

I made the same mistake and tried to do a couple of 5' intervals on the last few k's of Col D'Agnello (tops out at 2,700m) - tried to maintain normal power output for that sort of effort and completely blew up after about 90 seconds...

ravenvrider

I was lucky I was planning on hiring some garmin vectors which if I had I would have started the climb at my hour FTP which would have destroyed me and ruined my climb ....I was lucky the company didn't get back to me.

I only posted the information because in all my earlier research I had not seen anyone post anything more than a passing comment about the subject hence why i thought the loss was negligible, clearly if you are not interested in riding a climb at threshold it's irrelivant but at threshold it is very significant.

davidof

With those kind of outputs I would expect you to go faster than you did, altitude or not. The summit of the Alpe is only 1800 meters. I would put it down to more lack of riding uphill for an hour plus at FTP on a regular basis than than altitude. Maybe pacing? Maybe psychological as well as physiological. You have a very good power to weigh ratio and good power output for your age, I'm sure if you'd been paced up you would have easily broken the hour.

ravenvrider

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19696097#p19696097]davidof[/url] wrote:

With those kind of outputs I would expect you to go faster than you did, altitude or not. The summit of the Alpe is only 1800 meters. I would put it down to more lack of riding uphill for an hour plus at FTP on a regular basis than than altitude. Maybe pacing? Maybe psychological as well as physiological. You have a very good power to weigh ratio and good power output for your age, I'm sure if you'd been paced up you would have easily broken the hour.

I think its a bit of everything, it was certainly my first climb that length flat out, so possibly inexperience, i was certainly surprised i was able to significantly up my speed from the start of the last hairpin after the tourist office (under the bridge and through the shops then there is a hairpin) maintain through the roundabouts and even increase again up the last straight so clearly there was more in the bank, but the whole way up i was having to hold back due to my hr being on or just above my threshold so there was power left to use but if i went harder (for any length of time) than my hr threshold (which from my wattbike FTP tests was 176) i was concerned i would blow. I do now wonder if i should have pushed my hr a bit more...but who knows what would have happened if i had!

Yep for an old git i seem to be in reasonable shape thanks, i was thinking of attacking it again at the end of my holiday...but decided to ride the Telegraph and Galibier (not flat out) instead, that was a long day.