Hello dear forum users!
I'm planning to build a bike for my girlfriend and would like to ask for your help at first, at least, in choosing the right size frame.
A bit of context:
We currently have a couple of bikes, they are kind of "department store bikes", we bought them very cheap and without any fitting whatsoever (just used a "size chart" in the store); we're generally comfortable on these bikes. The geometry of her bike is identical to this one:
We use our bikes for touring. I'd like to build a new bike for her (it's the first time I'm assembling a bicycle) because:
1. I think it's going to be fun
2. the kind of bikes we'd like to try/ride (steel frame, no suspension in the fork, not "bulky" mtbs) are not to be found in the shops in our country (Romania). We mostly have mountain bikes and road bikes. We'd like to try and ride bikes like the surly lht, ridgeback voyage and so on.
Currently I'm very tempted (almost 100% sure) that I'd like to buy a surly cross check frame for her and equip that for commuting at first then maybe throw a rack and some fenders on it for some light touring (a few week long trips per year). Frame info for the surly cc is here: Cross-Check | Bikes | Surly Bikes
The shops around here also don't really take fitting seriously (there's one shop I've heard of from the local bike community that is rumored to do that, I plan to visit them this week) so currently I'm relying on whatever I read online for fitting and any help I can get on the forums.
My first and biggest problem appears to be choosing the correct size frame. The future owner of the bike is 165 cm ( about 5 ft. 5 in.) and has a 77 cm (30.3 inches) inseam length.
I've found other builds online for persons of the same height and people pretty much seem to go for either the 46cm frame or the 50 cm frame.
Standover height for the 46cm frame is 75 cm (29.6 in.) and 76.8 (30.3 in.) for the 50 cm frame.
I'm a bit surprised by this as that means that the 50 cm frame is out of the question because of the inseam length being equal to the height of the top tube!
Is the 2 cm difference between the top tube height and inseam length (for the 46 cm frame) too close for comfort (we measured the inseam without any shoes on, so maybe those will add another cm or two)?
The only other option is the 42 cm frame ... I suspect that that frame is too small.
I've also measured her current bike and .. it's pretty funky. Obviously because of its shape, the standover height is not an issue. I've measured the frame just as surly measures theirs and I've found that:
- the seat tube length is 40 cm (15.7 in); so a 40 cm frame, I guess...
- the effective top tube length is about 50 - 51 cm (about the same size as the TT on the surly CC and the CCs are regarded as having really long top tubes!)
- the chainstays are about 44 cm (again longer than the 46 cm CC by about 2 cm) - this worries me a bit because of the paniers clearence .. but maybe it won't be an issue).
I'm worried that the 42 cm and 46 cm frames might be to small; I'm also worried that the 46 cm frame might be to tall; I'm also worried about the top tube length since I'd like to fit trekking/euro/butterfly handlebars on it (so to not use a "road posture") and that will make the shorter top tube problem, worse; right?
I expect to tweak and change the various components (stem, saddle, handlebars) of the bike until I get a decent comfort on it; maybe that would be enough to make the 46/42 surly cc frame not small enough? Maybe I'm just worried over nothing ..
I appreciate any help/advice you can give me.
Sorry about the wall of text and thank you for taking the time to read this.
I've initially listed the effective top tube of the current bike as 53 - 54 cm, that was completely wrong, it's actually 50.5 cm, updated the post to reflect that.