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Fitting Your Bike Are you confused about how you should fit a bike to your particular body dimensions? Have you been reading, found the terms Merxx or French Fit, and don’t know what you need? Every style of riding is different- in how you fit the bike to you, and the sizing of the bike itself. It’s more than just measuring your height, reach and inseam. With the help of Bike Fitting, you’ll be able to find the right fit for your frame size, style of riding, and your particular dimensions. Here ya’ go…..the location for everything fit related.

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Old 06-30-14, 07:30 AM   #1
cupu
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Surly Cross Check build

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:
http://www.decathlon.ro/110241/bicli...original-3.jpg

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.
Cheers!

LE:
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.

Last edited by cupu; 06-30-14 at 10:57 AM.
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Old 06-30-14, 07:59 AM   #2
Kopsis
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The Cross-Check has a high bottom bracket (66 mm drop) which accounts for the high standover even in the smaller sizes. Potentially good for Cyclocross racing -- not so much for commuting/touring. Though, truth is, most modern CX race bikes have transitioned to a much lower bottom bracket. There are plenty of good steel frames (even from Surly) with more conventional geometry. Any particular reason why you're considering the Cross-Check?
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Old 06-30-14, 08:08 AM   #3
cupu
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Thanks for the reply Kopsis.
I chose the Cross-Check because the first option, the Long haul trucker, started from 56 cm height (for 700C wheels, which I'd prefer to have on the bike); other posts online seemd to praise the Cross-Check as a good commuter and decent tourer (also .. they have a green color for the frame!).
Actually, I'm open to any suggestion you might have.

Last edited by cupu; 06-30-14 at 08:15 AM.
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Old 06-30-14, 04:16 PM   #4
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You can use a longer crankarm with a higher BB ,

even toe clip pedals .. higher off the ground
means the tip of the TC wont scrape the ground before you have a pedal stroke in, to turn it over.

CC is OK a TIG steel TW Import .. sells well , not as long tailed as the LHT so sasquatches kick rear panniers ,
until they do a rear-set rack mounting. .
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Old 06-30-14, 04:33 PM   #5
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I don't have any idea if they ship to Romania, but Soma makes some nice frames that are comparable to the Surlys. The Triple Cross has a lower BB and more compact geometry that would get more standover without having to shorten up the reach.
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Old 06-30-14, 09:32 PM   #6
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fietsbob, Kopsis thank you for the replies!

As far as I can tell the soma triple cross cannot accommodate a rear rack; the double cross, though, can and is looking really nice! They "might" ship to Romania but I have to contact them and find out. The standover height for the 42 cm Double Cross is about the same as the 42 cm surly CC so I'm back a bit at my original question, so to reiterate (sorry!):

Taking the 42 cm frame for double cross/surly CC is 4 cm enough clearance between the "crotch" and the top of the top tube? What about the 2 cm difference for the 46 cm frame? It seems kind of close but it may be important because .. well .. we standover the bike at traffic lights and so on ...

I was worried that every 5'5'' person that I've read about online "seemed" to pick a 46 cm or 50 cm CC but even if I pick the 42 cm Cross-Chec/Double Cross I'm still getting a larger frame then what I have now (40 cm), so maybe it's not a big problem.

Last edited by cupu; 07-01-14 at 03:29 AM.
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Old 07-01-14, 07:04 AM   #7
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4 cm of clearance on standover is plenty. Even 2 cm is fine for on-road riding. Where you want a little extra is for off-road situations where uneven ground under the feet might actually be lower than the spot where the wheels are. Note that standover is affected by tire size. Most geometry charts will tell you what sizes they assume. If you plan on running anything significantly larger, you'll want to factor that in.
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Old 07-01-14, 08:14 AM   #8
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Hello Kopsis,

I think I'm going to go with the 46 cm frame; if I'll find it's too big, I'll exchange it for a 42.

Thank you very much for the help.
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