How much better is a TT/tri bike than a road bike?

What a tri bike allows for is to place the rider in a more aerodynamic position without compromising the characteristics of the bike. A road bike is designed with a rearward weight balance, moving forward and moving the weight over the front (i.e. steeper seat angle and weight over the handle bars as you do when you slap a pair of aero bars on) will make the bike less stable (even if you feel ok on the bike, I bet you're still micro correcting all the time, which is wasting a surprising amount of energy).

A well fitting tri bike (and fit is crucial) will make you faster, maybe not on the first ride, but as you get used to the position.

Going from a conventional (non-aero) road bike with clip-on aerobars to a properly-fit tri-bike would typically yield a speed increase of 2.5-3% at the same power output, assuming as many other variables as possible are kept the same (i.e wheels, tires, clothing, helmet, etc). For most triathletes, that's going to be a time difference of roughly a minute over 20km.

It seems this has been discussed in this forum previously (no surprise, really). I found this article in one of posts:
http://www.bikesportmichigan.com/bikes/difference.shtml

That's huge! I think for now, I'll just keep trying to improve my leg strength and stamina- keep trying to get over and sustain 40kph. But eventually, I'll plateau and will definitely consider a new bike that better suits my interest in triathlons.

In Taipei where I live, there are mountains everywhere. I live at the foot of a mountain and a group rides up it every morning when it's not raining. I definitely don't regret buying my road bike, but I think a new bike for my real interest will be necessary before too long. Thanks for the great information.

Our state time trial race is done on a 40k course and offers both an Eddy Merckx division (no aero bike or other aero equipment allowed) and regular TT races where you can aero-geek out to your hearts content.

One of my team mates is a very competitive Cat 4 who does the Merckx race on his road bike. He took 7th place and his time this year was 1:04:13.

By comparison, the Cat 4 7 place finisher was 59:47. So he rode about 1-1/2 MPH faster.

The winner of the Merckx race was also close to 1-1/2-MPH slower than the winner of the Cat 4.....I know it's very anecdotal and may not be the greatest sample to compare, but I but it's not too far off. My general experience is that I'm typically about 1-mph fast on my tri bike than my roadie (wearing similar kit and similar levels of effort) on solo rides. I'm sure the aero helmet and tighter clothes would boost that difference a bit.

That's a big difference and about in line with what was discussed earlier in this thread.

I'll be 50 next year but I believe I still can improve much, considering I'm still relatively new to cycling. I hope I can one day do 40k in about an hour. I did 1 hour and 13 minutes for a triathlon relay a couple of months ago (this included a bit of transition time since this was not separated). I was aiming for 1 hour and 10 minutes so I was happy. The triathlon started at 11 am and so I was out there basically in sauna-like conditions by the time our swimmer finished. I really, really feel that I can get it down to 1:05:00 or thereabouts for that 40k sometime next year. And then I think it will be time for me to move to a tri bike.

Edited by Trilogy 2016-11-08 8:49 PM