Will I lose general fitness whilst trying to raise my TT-bike FTP

Morning Gang,

this has been bothering me for a while and i can’t seem to figure it out on my own. I’m a half distance triathlete with a couple of years experience. My most recent a-race took place on a course with a lot of climbing and technical descents and so I trained on my road bike exclusively. I’m at a certain w/kg and naturally the bike fitness carries somewhat over to other disciplines. My brittle body can’t take much very hard running so I think vo2max in particular benefits me beyond cycling.

Now my next race will be on a flat course that favors the tri bike. I can put out much less power in aero position. So the goal for the next months would be to train mostly in my aero bars, with the aim of raising my FTP-in-aero so to speak. As I will be doing less work, albeit at the same or higher RPE, does that mean that I’ll lose overall fitness and might need to compensate for that in other disciplines?

1 Like

I had the same concerns and ended up doing the easier rides on the TT bike in the aero position as much as possible, building up the time in the aero position.
The hard efforts, like vo2max / threshold, I did upright.
After a while I noticed that my FTP on the TT bike got closer to my FTP in the upright position and I ended up doing most of the last weeks of the speciality plan almost entirely in the aero position.


If you’re doing less work then yes, your fitness will drop. Would suggest a more gradual transition to the TT bike, so that you’re still doing some hard sessions on the road bike to maintain the fitness.

Also recommend seeing a good fitter if you haven’t already, to make sure there aren’t other reasons behind the power gap beyond just time on the bike. E.g. a position where your hip angles are too tight. Or strength/flexibility limiters. Most people have at least some power difference between road and TT bikes, but if the position is good it really shouldn’t be that big. My TT position is basically just my road position rotated forwards around the bottom bracket. I find I can get back on the TT bike after a long period off and the power I can put out is pretty close to on my road bike within a few sessions.

1 Like

No, you won’t lose overall fitness. You will be starting at FTP of X Watts and finishing at X+Y Watts.

That’s good advice. Did you adjust your FTP for riding in aero or did you stick with your numbers and just sat up when it got too tough?

Do you want to be “fit” or do you want to be fast?
The point of training is to put you in a position to deliver optimal performance for a given event with specific characteristics. So for example, the crit race specialty plan would not be a good way to prepare you for a TT — you have to adapt your training to the demands placed upon you by the type of race you are doing.

If you do TTs or an iron man, then you have to train to put out power in an aero position. It wouldn’t matter if you could put out more power in an upright position, because that is much less aerodynamic and you’d be slower.

The way I understand your question, though, is that you plan to “dual use” training on the indoor trainer. However, I don’t think this is a good approach: primarily this just helps you to become a faster cyclist, but it isn’t optimal preparation for your other disciplines.

1 Like

Thanks, those are good points. For more context, I’m primarily a half distance triathlete and want to shoot for 70.3 worlds early next year. So I want to be fast. My a race this year was a half distance on a tough course that heavily favored the road bike, hence I did my recent 6 months block on the road bike. Next course will be flatter so now I need to transition back to my TT bike. Right now I am putting out much less power in my aero position.

I guess what I am wondering this: Taking into account that for triathletes a fair amount of fitness carries over between the disciplines, Should I test my FTP in aero position and start from scratch, building it up from there in aero position? Or rather like others have mentioned try to transition my already sufficiently high “road bike FTP” gradually to aero position?

I would retest in the aero position since this is going to be the position you are going to be training in. That means the difficulty of the workouts scales with the FTP for that position. Otherwise your workouts would be too hard.

not necessarily lose fitness because you focus on FTP efforts on the TT bike, but would lose fitness in specific energy systems if you don’t stress them at all during this period, ie vo2max.

Good luck with the training!