How much of a drop in power from road to time-trial position is realistic?

What it says in the title basically I have powermeters on both my road bike and my time trial bike. On the road bike I can probably do about 340W for an hour. On the lo-pro on the other hand I did an approximately 1hr time-trial this morning and averaged 280W (not a one-off either.) Is such a drop-off realistic, or is one of my powermeters jiggered? And if it is realistic, is it a sufficiently large difference that I ought to spend a lot of time getting used to the TT position?

FWIW I still go siginificantly quicker on the TT bike...

 

I think it is fairly common... here is a recent thread that may be of interest.

http://www.cyclingforums.com/t393443.html

 

Ah - should have searched before posting. Thanks very much.

OK so one orginal question - is there any way in CP of having 2 simultaneous values for FTP depending on bike (I could change my FTP every time I switch bike I suppose.) It's bad enough only managing 280W for a race but it's a real slap in the face to only get about 80 TSS for it

 

You could create another athlete, say Joe Timetrial and put all your TT numbers in there.

 

Agreed-I save all my races (Edit-copy-paste) in a seperate folder for analysis so that I retain my warm-up, race and cool down as a single simple file for TSS, TSB in CP.

Its is very common for you to drop ftp for TT (15 watts some say), but your drop seems more than you could make up for in aero, but you said otherwise. I am close to my TT goal of the year so I am on my TT bike a couple times a week as well as still racing my road bike. My goal is to compromise and have my ftp on the TT bike to be within 10 watts.

I know at my last TT raising my wattage only 15-20 watts would have gained me 1mph with the tailwind and maybe 0.2 mph into the headwind. Maybe next ride on your bike on a flat section experiment with what speed you can go at say 280 watts and then try 300 watts and if its siginifcant then by all means, chnage something (bar height, saddle height or fore/aft) till you can get closer to your road ftp.

Ray

 

Before you start messing around with different FTPs, or make any drastic changes to your TT position to get some of the missing 60W back, I'd find away to verify that the powermeters on each bike are consistent with each other.

IOW, verify your measurement tools before you draw conclusions and take action.

 

I think you should only loose 5-10% max. Not sure if there is like a six km climb near you can then compare if the time and avg watts are proportional. Also, riding up hill on the TT bike will help you get more efficient.