My ‘tri’ bike is built around a frame using slack geometry. It fits well and I’m comfortable on it. The current setup has the seat about 5cm behind the BB. I plan to focus on 1/2 IM distance events.
Would switching to a tri-specific geometry frame reduce my times - either via faster bike splits and/or faster run splits? I know there’s no definitive answer, but is the primary purpose of steep geometry “just” comfort or is there something else to be gained? If I’m comfortable an aero on my current frame, would I gain anything by switching to a steeper frame?
Maybe… maybe not. It depends on how well you are setup on your current ride and if the aero/power trade-offs of a steep setup work for you.
Seems to work for some, but not for me. When I went from my 73 degree road bike to a number of 78-80 degree bikes in the early 90’s I suffered for a couple of years with slow run splits due to quad cramps. After getting tired of trying to adapt I pushed by seat back again (thankfully I was on a Softride at that point) shortened the aerobars and my bike and run times improved dramatically and immediately.
Your results may vary as they say.
Depending on how many views and responses you get, be prepared for a can of worms to open on this one. There have been several studies referenced on this site regarding either cadence or forward geometry, though I don’t remember which one, that indicate it leads to faster run times.
I think that a lot of it comes down to personal preference. If I only did 1/2 IMs and IMs or traditional non-drafting events, I’d be on a bike with a 76+ degree effective seat angle like the Javelin Arcole that I have. For a true aero position, I find that I can get lower this way and remain more comfortable as better than 1/2 of your weight will be supported by your elbows and upper arms at the front.
Since I do a mix of racing styles with drafting and non-drafting, I ride a road bike that has a 73 degree seat angle. I’ve got a Thomson straight post and the seat slightly forward on the rails. So, I’m probably 75ish degrees. I also use vision shorty bars. I certainly don’t think that the position is as aerodynamic, but it is comfortable.
You may find that your power between one position and the other changes a fair amount as soon as you make the switch, but I think that there will be adaptations to whatever position it is you choose and the power arguement becomes less important. If it were easy to try a different position without breaking the bank, it might be worth it. Do you know of anyone where you live (since it is a good tri community) who would loan you a bike for a month or so? My $0.02.