Triathlon - tri bike sizing

Hi all,

I am new to the forum, and am seeking some advice on proper sizing for a used tri bike that I'm looking to buy. I am 5'8 3/4" tall, with an inseam of 31". I assume that the best size would be a 54cm bike, but I've found a few that range from 53cm to 55cm and am wondering if these would be alright. Any advice on what to do? Thanks!

A real hard question to answer - and best left up to the bike shop selling you the bike. So much has to do with the top tube length and seat tube angle of the various bikes. I think your close in your guess as to the size. I am 5'9" and a 32" inseam (so close to you). My road bike is a 54 and my tri-bike is a 54 on a Cannondale IM 5000, and a "small" (closer to a 53") in the Trek-TT.

Good luck

I highly recommend you go to a triathlon specific shop to get fitted (if there is one in your area). FYI- I am the same height/inseam as you, and I ride a 54 road bike and a 52 tri bike. I feel as comfortable on one as the other.

I second the previous responses. I have a 57 LeMond Zurich and just ordered a 56 Specialized S-Works Transition last night. After fitting of course.

Hi all,

I am new to the forum, and am seeking some advice on proper sizing for a used tri bike that I'm looking to buy. I am 5'8 3/4" tall, with an inseam of 31". I assume that the best size would be a 54cm bike, but I've found a few that range from 53cm to 55cm and am wondering if these would be alright. Any advice on what to do? Thanks!

Bike sizing can be rather complicated. For example, I have a Guru Tri bike on order, and according to my measurements I do not fit an off the shelf size. Guru is building a bike that is basically a combination of a 57 & 55 cm bike for me. Find a shop that does precise fitting, find out what you really need, and then have them adjust the bike for you when you get it.

I was given a xmas present of a bike fitting at Florida Bicycle Sports in St. Petersburg, FL. The fitting took almost 2 hours, and there was extensive use of video during the fitting. The result was a substantial difference from the way the LBS fitted the bike when I bought. The difference on the road was phenomenal, and I started winning club sprints. Find a shop like them where they know what they are doing - unlike the typical LBS.

drechlo: What size is the bike you're considering? I typically ride a 55 or 56 cm frame depending on the manufacturer. If the tribike is close in size to what you're riding as a road bike you should be OK. Nothing beats being fitted for a bike though.

Thanks everyone for your replies. Your advice is much appreciated!

ZachJones, the bike I'm considering is a 53.

ZachJones, the bike I'm considering is a 53.

53 may be a little small, but heck, check it out and see how it feels to you.

I'm 5'8" w/32" inseam. My Kestrel 52cm fits me so well that one might think I had it designed for me. You might want to take in consideration how the builder measures its frames... Center-to-center, center-to-top, or top-to-bottom... This will greatly affect the sizing...

Go to a LBS that has all the bikes (or at least most) you are interested in and spend the money for a fitting. Based on that, test ride and select the frame that you are most comfortable with. Well-known fact; if you are comfortable, you will be faster!

does the tri bikes typically fit well as long as you stick to the same top tube and similar seat tube as your road bike or would it be different since your almost in a time trial position?

does the tri bikes typically fit well as long as you stick to the same top tube and similar seat tube as your road bike or would it be different since your almost in a time trial position?

It will be different. To way oversimplify, you will probably need a shorter top tube than for a traditional road bike. For a lot more detail, here's a good article on triathlon fitting.

http://www.slowtwitch.com/mainheadings/techctr/bikefit.html

Along with some others:

http://www.slowtwitch.com/mainheadings/techctr/techctr.html

-s

When I bought my tri bike recently I got the same size frame as I ride on must road bikes (56cm). If the store would have had a 55cm frame in stock I might have tried that size to compare the two. I think as long as you get a frame that's close you can tweak your fit by adjusting seat height, swapping out stems, etc.