i can 100% agree with this. i would never ride my tri bike in any sort of city traffic. that makes perfect sense.
for the sake of the discussion though, eliminating the safety factor, and focusing PURELY on returns from training, it seems to me that one would want to spend as much time in aero. train like you race and all that.
my only citation for this would be a recent podcast the trainerroad guys did (with them referencing the 40k TT they were doing). all of their FTPs were around 20% or so (from what i remember) lower in aero than on their road bikes. it would seem
to me to train in that position to get stronger in that position.
i would recon that if top athletes are not doing this then they are already towards the top of their game and maintaining fitness and incremental gains are what they focus on.
this is all pure conjecture on my part though. maybe i need to pull my tri bike off my trainer and put my roadie back on. :)
This could get into a really long discussion filled with some conjecture but I'll try to keep this brief. I am sure Rapp might add his thoughts, but I believe part of what he might say is he would do specific work in his TT position, but the blocking and tackling riding (base work, recovery work, etc) was just not comfortable to do compared to his bike. I find in Florida it is really hard to ride hard watts because you are going so fast that you are skipping off the pavement and can't get good power transfer and it is hard to get a good workout. In a race, I am likely riding 50-120 watts lower than those intervals where I am really throwing down power. Going slower actually helps me put out more power which helps increase the HR and increase the the fitness response. Skipping back to Rapp, there is something to be said about soft-pedaling on a TT bike. If you are putting out watts it lifts your body off the saddle a bit and relives some pressure. Top pros tend to have some of the most aggressive positions, and while it might be fine if you are putting out a lot of watts. Relatively low watts rides (ie soft-pedaling) are tough and much better suited for the road bike.
For me, there are some other things too. I just don't think the TT position is good for the long-term health of the neck and some arteries in legs/hips, but also, riding the TT bike is just not a fair fight unless I am riding with some very choice cyclists. Most cyclists don't have a TT bike anyway and out of respect I also wouldn't bring one to the group ride. Regardless, I am a firm believer in doing work, and one of the best mental tricks I have found is to handicap myself in training. For me, on the bike, I have for years taken a cross bike with 42mm commuter tires, baskets, rack etc on group rides. This POS versus their aero carbon frames with GP4000s is a knife versus gun fight. While I might struggle to stay on I don't have to think about anything else than staying attached and I get a better workout and thus get better at cycling. You can make the same point that riding a road bike is just more enjoyable and more enjoyment equals more riding = better fitness.
Just a couple of quick anecdotes. I was leading a large group ride earlier this on a volunteer basis, it was one of two real rides I have done since October. It was a bunch of triathletes, and I asked them why they didn't bring their road bikes (it was fun training not serious training) and they said they just weren't comfortable on them. That to me is classic thing I hear and I don't know if it is familiarity or really comfort. If it is about comfort I would suggest they weren't fitted to their road bikes properly. Ideally a road bike should be more comfortable than a tri bike but I think people get confused with familiarity. They are too familiar with the tri bike and know how it feels and handles. I also met a set of ladies locally last year who said they preferred their TT bike because they felt so slow on their road bikes.
Second anecdote, I haven't ridden since October really outside of one ride with some training partners and one volunteer ride. I hadn't ridden my TT bike since Louisville and last month I entered a local race on Friday at 6pm (race was Saturday morning). I figured I should at least ride the TT bike once before the race and to make sure the tires still held sealant and the bike worked so I took it for a quick 30 min spin. The end result was a win with a bike bike split against some choice amateurs. The ride was pretty pathetic but that was more about my fitness than about the bike. Point being that I still road minutes faster than anyone else over this 11 mile bike ride. How much did a I lose in specificity of not riding a TT bike. I would argue a very minimal amount.
Regardless, if at the end of the day you enjoy your TT bike then ride it. If you like your road bike then ride it. To me the answer isn't really about choosing one or the other... it is ultimately just about riding.
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