Bicycle sizing for my girlfriend..

[Andrea]

I'm 5'6" w/a 30" inseam and I ride a 46cm crosscheck. I was trying to decide between that and the 50cm, but went with the 46 because the standover on the 50cm is 30.3" (yeah, I'm mixing my metric & imperial units ) The reach on it is definitely shorter than my road bike (surly TT: 52.8cm Blue Rc7 TT: 54cm), but it doesn't bother me for CX racing.

In other words, the Surly's 50cm standover was barely too big for me, but the TT was OK, and I'm a little bigger than your GF, so the 50cm is likely going to be too large for her.

[Triskeliongirl]

Height is only one paramater. I am 5'4.5" tall, and have long femurs and a short upper body. My best fitting bike is a 19" terry road bike with a 49cm TT. I also need a slack STA (73 degree or less) to fit my long femurs, and even then my saddle is all the way back on a very laid back seat post. This is another reason I need such a short top tube, I sitting further back than most, increasing my reach.

I could never ride a bike with a 54 cm top tube!

[aicabsolut]

I'm 5'7" with a 31.5" inseam. I've got long arms and a flexible lower back. I ride a 54cm road bike with a 54.8cm effective top tube and a 110mm stem. I can make a 52cm fit (with a 53something TT), but I prefer a 54. A guy I know who is about 5'10" rides the same bike with almost the same setup, only his seat is a lot higher.

I think that based on all our stats you can get a good starting point for her, but she's going to need to sit on a bunch to figure out what size is best. Different brands have different geometry, so maybe she'd like a 52 in one but a 49 or 50 in another.

[kie_fujo]

i don't know a whole lot but i'm 5'4" and i ride a 48cm. i had a 50cm and it was too big causing me a lot of shoulder pain. i also ride a road bike though.