I’m trying to make a decision and would appreciate some input. I’m looking at purchasing a tri bike and have been told that I could be fit on 2 different size frames – either would work they say. One is a 50 with 700 wheels, the other is smaller a 48 with 650 wheels – there is probably a 3.5 cm difference in the length of the top tube. I currently ride a 49 with 650 – I’m 5’3" with a 27.5" inseam. Is there some rule of thumb when selecting a frame that if you fall between 2 sizes to go with the smaller of the two? The convenience of the 700 for wheel and tire options is appealing but I’ve also been riding a 650 bike for over 6 years. I’m leaning towards the smaller bike. I’ve also been told that I’d be faster & more comfortable with the 700 wheels.
Your overall height makes you a prime candidate for 650c. Don’t let anyone tell you that you would be faster and/or more comfy on 700c wheels - find out for yourself. Something to consider: You may have a toe-overlap problem with the 700c bike. Some folks are ok with this, others are not.
I suspect that the ‘faster and more comfortable argument’ comes from a person that believes that the 650 wheel size is a thing of the past. My wife is about your size and got a schpeil from a lbs guy that 650s were not for her. i have no idea where this comes from. i am 6’2" and the nothion that a person that is almost a foot taller should ride the same wheel size seems wrong to me.
in any case i think you should stick with 650’s. you can also find smokin deals on 650 race wheels.
“I’ve also been told that I’d be faster & more comfortable with the 700 wheels.”
Must have been told to you by some one who doesn’t ride 650’s… I personally prefer the smaller wheels, and I’m 5’9"+. Anyway… Ride both, set up for you, and see which you prefer.
Polling the people on Slowtwitch about bike fit is probably the WORST thing that you could possibly do. The answers that you get, - other than GO SEE A PROFESSIONAL BIKE FIT PERSON, - are only going to hurt you.
You are risking more than comfort and less power and speed: but possibly injury if you don’t go to an independent fit person and get yourself measured, interviewed, stretched, etc. etc…
Save yourself a lot of money, time, discomfort, and possibly injury, - go get yourself a professional fit…
I understand your point, but that’s the real crux of my question – the professional fitter is telling me I can go either way and is urging the 700 because of the convenience of wheels, etc. Note: he ia also not the person selling me the bike.
Polling the people on Slowtwitch about bike fit is probably the WORST thing that you could possibly do. The answers that you get, - other than GO SEE A PROFESSIONAL BIKE FIT PERSON, - are only going to hurt you.
You are risking more than comfort and less power and speed: but possibly injury if you don’t go to an independent fit person and get yourself measured, interviewed, stretched, etc. etc…
Save yourself a lot of money, time, discomfort, and possibly injury, - go get yourself a professional fit…
I’ve seen good fit information coming from Slowtwitch and crappy fits done by “professionals”.
the professional fitter is telling me I can go either way and is urging the 700 because of the convenience of wheels, etc.
See my post above about “professional” fitters (rolling eye smiley).
Do a search here of “650” or “650c” and posts made by “slowman” and you’ll get some good answers by the man himself (and see how the things the “professional” fitter claims are bs) .
How will your fitter account for the 3.5cm difference in top tube? Is it a different stem/aerobar combo? You may technically fit on either frame, but one might handle better than the other. At 5’7", I was told by two different fitters I’m right on the cusp of 650 and 700. At 5’3", I’d be inclined to think you’re closer to 650.
As for 650 versus 700, I’ve had both. The argument pro and con is long and complicated. For me, I owned a 700c road bike and a 650c tri bike for a couple years. It was a pain maintaining spare tires and tubes in both sizes. Later, I sold the 650c and both bikes I own are 700c. Makes life easier being able to swap wheels and tires to meet the demands of different race courses.
I went and got a professional fit and could immediately tell the professional did not know a thing about tri fitting.
So I fit myself. I don’t see any reasons why I should require a professional to do this. I can tell when I am comfortable, I can tell when I am aero as well as anyone else who doesn’t have a wind tunnel.
I can tell when I can pedal powerfully…
You have just made a HUGE mistake.
Polling the people on Slowtwitch about bike fit is probably the WORST thing that you could possibly do. The answers that you get, - other than GO SEE A PROFESSIONAL BIKE FIT PERSON, - are only going to hurt you.
You are risking more than comfort and less power and speed: but possibly injury if you don’t go to an independent fit person and get yourself measured, interviewed, stretched, etc. etc…
Save yourself a lot of money, time, discomfort, and possibly injury, - go get yourself a professional fit…
I’m concerned about the 3.5cm difference in lengths of top tubes. If the frame geometries are the same, this is a problem. (If the geometries are different, then there may be no issue.)
The reason is this. Standard stems come in sizes between 9 cm and 13 cm, 4 cm total range to adjust reach. So when I am helping people find a frame, I have always tried to find the frame that puts them in the middle of the range, so they have some range to adjust. Also, very short and long stems are available, but really effect the handling, which is an other reason to try to target the middle of the range.
So I would say that with top tubes that different, at least one of these bikes is not a good fit.
If the seat tubes are different angles, then maybe your fitter has determined that you will require approximately the same size stem on either bike to achieve the same reach. In which case, no problem.
Paul
P.S. - I am not a professional fitter, but have helped many friends through the years.
““I went and got a professional fit and could immediately tell the professional did not know a thing about tri fitting””
Then I would call that person not very professional…
And, I would further ask, - what about your flexibility? What about your feet? Do you, or do you not require arch support?, - for example? How flexible are you? What is your weight? What is your inseam length? What is your torso length? How flexible is your back?
You may be able to tell when you “feel” good on the bike for 15 minutes, - but do you feel good after a 5 hour TT, - or will you not be able to run? Where is your knee located in relation to your cleet when your pedal stroke is in the 9/3 o’clock position???
You asked what your ideal frame size is. Well, - there also isn’t a standard frame size. After a good, professional fit, you’ll get your perfect dimensions, - taking into account flexibility and many of other factors too numerous to elucidate here that you can attach to frame dimensions of various manufacturers. I can tell you that the frame dimensions of Merckx bikes are different than Colnagos…
There’s a heck of a lot more to a good fit and finding the right bike that matches your unique dimensions than feeling good, being powerful, and being Aero.
With as many people as I see on the roads who, (just about anyone who has had a good pro fit can tell), is riding a bike that is completely wrong for them, - I believe it. There are probably more than a few people claiming to be something that they are not. And perhaps a lot of shops that are trying to just sell you a bike, any bike, may also claim to be “professional” fitters…
And, - Perhaps i was a bit too strong in saying that no one here can help as I am betting that Tom Demmerly does great fit work. But, with so little information from the original post, and, so much that needs to be done by a really good professional fit, in so many areas, - it is HIGHLY UNLIKELY that slowtwitchers are going to be able help without more information and the experiences, and certifications, and the 5 to 8 hours, that a GOOD PRO can provide…
Apologies for my vociferousness… From my experience, my fit guy was a huge revelation to me and I learned so much. The 8 hours that I spent with him was incredibly informative and I realized that what he brought to the table was well worth the $350 and that there were so many areas where one can go wrong, and possibly even injure oneself due to purchasing the wrong bike. Indeed, - I experienced the difference, - (I didn’t get injured), - but I did feel exactly what he is saying upon riding my old bike vs the new one that was the correct size.
All this being said, - and if it is possible, - (yeah, it might be prohibitively expensive), - but I would seek a second opinion. And, try to find a way to ride both. I do believe that there is a “workable range,” - so perhaps this person is cool and either size wheel can be made to work. If so, - find a way to ride both. You’re the customer, and getting it right is important and the bike is costly, - but getting the wrong bike is much more costly.
The reason is this. Standard stems come in sizes between 9 cm and 13 cm, 4 cm total range to adjust reach.
Stems come in a much broader range than 9-13cm… More like 5-15cm. I have seen longer, but they are not readily available.
Going to a professional fitter is definately the way to go. Obviously there are guys out there that say they are “pro” fitters, but are not. That is why you need to do your homework. Ask around your local Tri community and see who people use. Call your local Tri club or a local coach and see if there is anyone that they endorse, or send people to.
Coming onto ST and saying “this is how tall I am, this is my inseam, what size bike do I need?” is not going to get you good results. Fitting is a much more involved process than just your height and inseam, which you should already know if you have been fit.
Speaking of your fit… why is the fitter suggesting two bikes with enormously different top tube lengths?? Even accounting for different seat angles, there shouldn’t be such a large disparity between the two. If you are indeed interested in either (or both) of these bikes, request to have them set up to your measurements so you can ride each bike. If they are a good shop they shouldn’t have any trouble with you taking the bike for an hour or more so you can get a good feel for it.
On the other hand, it sounds like you are a little skeptical of the recommendations your fitter has made. I think you might want to go elsewhere to get a second opinion. Where are you located? I am sure myself or someone else on ST knows a good experienced fitter in your area.
