Frame Size

[bjorgenson]

I am 6' 4" and have a 36" inseam. I just bought a Trek 1000 (I'm a newbie) with a 58CM frame. Just wondering if this frame is a bit small. I upgraded my stock stem with a carbon fiber stem that gives an extra inch of height. When Ihold on to the bottom handle bars, my knees are about an inch from my elbows. Is this normal? I just road 20 miles today and it felt comfortable the whole way through.

 

[derrick VL]

[Take a look at: http://www.bsn.com/Cycling/ergobike.html

 

[leona]

My husband is 6'4", with a 37" inseam, and he rides a 58cm Look, so your probably ok, especially if your ride was comfortable. If your still worried, find a reputable coach or shop that specializes in fits. They should thouroughly measure nd manipulate yor position and compare it to BPM/watts exerted. Expensive, but well worth it.

 

[Babbar]

Originally posted by bjorgenson
I am 6' 4" and have a 36" inseam. I just bought a Trek 1000 (I'm a newbie) with a 58CM frame. Just wondering if this frame is a bit small. I upgraded my stock stem with a carbon fiber stem that gives an extra inch of height. When Ihold on to the bottom handle bars, my knees are about an inch from my elbows. Is this normal? I just road 20 miles today and it felt comfortable the whole way through.

I'm 6'3" with a 36" inseam and depending on how the bike is measured, c-c or c-t, I take either a 58cm or a 61cm, respectfully. The bottom line is if you are comfortable after about 300 accumulated miles, you made the right choice.

 

[serottarider]

It sounds as if the fit's about right for you since you say that 're comfortable. Longer rides (2 - 3 hours) will soon tell you if the bike is fitted incorrectly!

Now, I'm 6'3" with a 34" inseam and I ride a 61 cm Serotta frame.

Fit on the bike is a highly individual thing! Inseam is a good starting point for estimating frame size, but thigh length (either longer or shorter than "normal") affects the size you need, as does your overall flexibility, pedaling style and a number of other factors. I have relatively long thighs for my height.

Because the saddle position is capable of accepting such a wide range of adjustment to achieve the best biomechanical fit, the frame's Top tube length might often be more of a determining factor in frame selection for some riders. This is particularly important for women riders and also for men with relatively short torsos, or relatively long torsos.

Then again, your position is likely to change as you train. My flexibility has improved significantly and so I now need more Top tube length than I did a few years ago. I also need a slightly lower handlebar position relative to the saddle height than before.

 

[Mouse Potato]

Originally posted by serottarider
... the frame's Top tube length might often be more of a determining factor in frame selection for some riders. This is particularly important for women riders and also for men with relatively short torsos, or relatively long torsos.

That's the impression I had from reading various bike fit articles and frame reviews (I'm a newbie), but I was asking about frames at a bike shop last week and the guy there said they start with leg length (inseam, presumably) and that top tube length doesn't really come into frame selection because they adjust for that by changing the stem.

I was asking about choosing between different manufacturers and models rather than choosing the best size in a particular model, and admittedly it wasn't the main reason I was there (I was after a new helmet, but I thought it would be a good opening to perve at the "upstairs" bikes), but is that an equally valid approach?

 

[ajo]

The top tube length is most important, since the handling of a bike is mainly determined by the lenght/wheelbase of the bike. (In addition to frame/fork angles, material etc.). Change of stem should only be used for minor adjustments, should normally be 9-12 cm. Going outside this range will disturb the weight distribution between the wheels, with impact on the steering and stability.
Oposite, moving a seatpin up or down had nearly no effect (within normal limitations), just be shure it's possible to get the bar in correct height.

 

[serottarider]

Good point on maintaining the saddle/handlebar height relationship, Ajo.

Additionally iIf you are moving the seatpost up or down more than a very small amount you'll probably also need to adjust the fore/aft position of the seat so as to maintain the hip/knee/ankle/pedal relationship.

Moving the seat up will move the seat back relative to the bottom bracket.

Thanks!

 

[Mouse Potato]

Thanks, ajo & serottarider... that's useful info!

(Although at this stage the biggest impact on "steering and stability" for me will be my (lack of) competence )