I have a Lemond road bike with 700 cc wheels. I am fortunate enough to have a Litespeed Saber with 650 cc wheels too. Three months prior to my race I intend to train exclusively on my Litespeed. After my race, my plan is to train on my road bike and make a similar switch again before my next race.
Question: Does it make sense to make such switches?
I presume you are racing on the Litespeed. It is good to practice on the bike that you will race on. It would be unreasonable to expect that you could go from a road bike to a tri/TT tpe bike without any practice riding it and do well in a race. Your body would just not be accustomed/comfortable to the position required. However, I doubt that you would need three months of riding/training to get comfortable or to achieve maximum performance each time you switch. Consider the riders in the European Peleton. They switch from road to TT to road all the time. They also ride the different bikes on training rides to maintain their “form”. They spend time riding new bikes or positions to get comfortable with them. They do pretty good without the luxury of riding three months before each switch. I think you can do pretty good too, with far less than three months of riding a specific frame before racing it.
A bigger issues is fit rather than wheel size. The geometries of a Lemond road bike and a Litespeed Saber are completely different.
Variety is the spice of life. Why not ride the bike you like/want to ride?
I also have a Lemond (700 Zurich) and a Litespeed Saber (700). Last season I found that long periods on either made transitioning back to the other a little painful for a few days, and the change in geometry awkward for a while. This season I’m alternating every other week on the two bikes - and I think I’m better for it. I live in rolling hills, and ride mountains about 6 times a year. When I would be off the tri bike for a while last year, then saddle-up the roadie ride and go to the big hills - it hurt.
The road set up tends to work my glutes and mid-quads more, and the tri set up works my lower quads. With a week on one, then a week on the other, I’m working everything on a regular basis. I’m finding this translates to slightly less-sore quads on real hilly run courses. Maybe its better quad all-around conditioning, maybe its a week of rest from one type of quad exercise…who knows. But, it seems to be working. Not my intent for this alternating bike/week thing, but just a good result.
for my oly training I would use my trek 5500 for long rides, hillwork, and early-season bricks; then my P2K for intervals, late-season bricks, and racing. in terms of training time, this translated to using my P2K once a week (trek 3x/week) except near race season where i would use the race bike 2x/week. i found this enough to remain comfortable on the p2k despite the huge difference in set-up. when i was training for my first IM (before i hurt myself!) i finally used the P2k when i started hitting 4 hours for my long ride (when my ride was on the flats). the first few times i did this it was definitely not comfortable. but as i progressed it started to feel better.