Frame Size

[VFDRider]

Just curiously,

Coming from a 19" Jamis hardtail, I'm looking into buying a new frame; as it is listed as an 18 or 20" option only, at 6'1" w/ a 33" inseam, any thoughts on the best fit?

I realize that top tube length plays in here, and the frame I'm looking at is pretty much the same dimensionally speaking as the Jamis was, just curious what others had to say.

Thanks!

[tuba_transport]

IMO...................

Top tube length is pretty much the deciding factor in bike fit with regards to frame sizing. All other geometry has more to do with handling than fit.

I have a 32" inseam and am 5'10.5" or so. I fit in between a medium and large in most manufacturers.

I have a 1998 medium Gary Fisher Mt Tam setup as a SS with a 120mm stem. That bike is Genesis Geometry which means LONG top tube for the overall proportions. It might actually fit me a little better with a 110mm stem, but I had a 120mm lying around when I built it up.

My other bike I ride often is a 2005 large Ellsworth Moment with a 90mm stem. That bike uses standard geometry. It might fit a hair big for me. I tried the medium at the time but felt cramped. The large feels slightly too big.

If you have a bike already which you really like the fit, then measure the effective top tube length and try to get something close to that.

[VFDRider]

Thanks I actually think thats what I'm going to do, as I'm kind of between frame sizes, and have a stem length I like I'm just going to find something comparable on TT length and adjust [to a point] with seat post length and placement.

[tuba_transport]

Thanks I actually think thats what I'm going to do, as I'm kind of between frame sizes, and have a stem length I like I'm just going to find something comparable on TT length and adjust [to a point] with seat post length and placement.

Actually I would change stems before I screwed with pedal to saddle distance. Knee placement over pedal spindle plays a huge part in pedaling efficiency. IMO, the order of adjustment/precedent is seat height, seat fore/aft in relation to knee over pedal spindle, then stem length and handlebar height.

[VFDRider]

After doing some measuring and quick research, the old bike seems to have a TT length of 59.1cm, and the new potential frame a 59.4cm so that ought to work out as far as TT goes.

[VFDRider]

After comparing frame size, TT lengths, dimensions of both bikes and then measuring up against my 19", I decided 20" was too big so 18 it is. Thanks for the help tuba transport!

[rizetech]

http://sheldonbrown.com/kops.html

no doubt the kops is a reasonable starting point but... the article has some valid points - personally i've never made this adjustment, for me cleat position was the biggest factor next to seat height in getting good ride results.

but, i think the 18" was the right choice

[tuba_transport]

http://sheldonbrown.com/kops.html

no doubt the kops is a reasonable starting point but... the article has some valid points - personally i've never made this adjustment, for me cleat position was the biggest factor next to seat height in getting good ride results.

but, i think the 18" was the right choice

I have read the argument before. Most of the debates I see are an inch this way or an inch that way.

It is the same for most of the fit.

Heel on pedal at bottom of stroke with locked out knee and without hip swing.
Knee over pedal spindle with ground parallel cranks.
Arms at 90 degrees to torso while seated.
Handlebar height at whatever weights the wheels to your preference, balances load between butt and hands the best, and enhances aerodynamics and/or comfort if applicable.

It is all a starting point to fine tune from. I have seen people with way laidback saddles. Some have handlebar heights so high the front wheel washes out and climbs are challenging to keep the wheel down. Others riding with a pronounced bend in the knee on the bottom of their crank stroke.

Get much closer to an efficient ballpark fit and ride the bike like that for a week or two to get used to the new feel. Then go back to your old fit and decide which one gave better results.

Knee over pedal is a MUCH simpler way of getting VERY close to a good fit for MOST people. All the other methods read like a college dissertation. And in the end most everyone is going to still use the results of those fancier methods as a starting point and adjust personal preference from there. The results will likely be very very close to identical.

ps. I just reread the article more clearly and it is really not applicable here. It deals more with frame geometry design in order to take into consideration not just the seated position, but also standing sprinting and standing climbing. These two standing positions have nothing to do with saddle position. They have to do with hand position on the bikes geometry in relation to feet. The saddle is not part of the equation in this article.