Bike sizing for the oddly proportioned?

so, i spent the summer riding my childhood bike for exercise, a toys-r-us mountain bike which my brother broke all the gears on a decade ago and no brakes. i really enjoyed riding, but the bike was a nightmare. now, with the help of some amex reward points, i'm finally getting my first 'real' bike. and here is my dilemma:

how to fit a bike that I won't get to try?
also, my proportions are a bit wonky.

i was planning to get the trek fx 7.5, pretty spendy for me, so i want to be sure it fits right. it comes in a regular or WSD frame, but here's where it gets complicated...

i'm tallish, 5'8", and 50% of my height is in my legs; that's 34 inches. (average is 45% among women). to make the matter weirder, my arm span is two inches larger than my height (longer arms are typically a male trait). size charts which go by height put me on a 17 to 19 inch bike; charts which go by inseam put me on a 21 to 23 inch bike (that seems really wrong, that would be the same as my 6'4" brother)

So if i was only leggy, i would go for the largest WSD, 19", with a stand over height of 30.2 in (seems reasonable). but i'm worried that my orangutan arms would make the WSD feel cramped. or would my short torso make up for that? the 20" men's frame has a stand over height of 30.8 (also reasonable), but would I feel too stretched on that frame? though I could technically get my leg over the 22" men's, i'm sure that's too big. maybe women should be fitted for men's bikes with a tube sock stuffed down their pants. lol. :p

long story short, would the 19" WSD fit the best?

I wish I knew the answer. I'm 5'6.75", and my inseam is about 32" (crotch to floor). For me (arm span approximately equal to my height), my limiting factor is reach. I'm shopping for a new road bike, and I have to go down a size to accommodate my short torso.

However, it may be different for you, due to your arm length as well as other factors (flexibility, fitness, etc). Go to the bike shop and ask to try one of each (WSD and unisex) in your size range, if they have it in stock. Then pick the one that feels best (after going to another shop if you have the option and testing out what they have there). There are tweaks that can be done, within certain limits, by a bike fitter to help improve comfort and take into account your differences from whatever nonexistent person Trek uses to design their bikes. :p

Quote:

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Originally Posted by Jaq

i'm tallish, 5'8", and 50% of my height is in my legs; that's 34 inches. (average is 45% among women).

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That just about determines that you need WSD. (BTW, I have about the same legs, but I'm little bit taller.)

Quote:

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Originally Posted by Jaq

(that seems really wrong, that would be the same as my 6'4" brother)

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Actually, you have the legs of a typical 6'4" guy, so, going by just leg length you'd end up with the same size.

Quote:

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Originally Posted by Jaq

long story short, would the 19" WSD fit the best?

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Of the non-WSD sizes, the 20" would fit the best: One size up would be way too long, and one size down would not be tall enough (in the front of the bike). The 19" WSD has the same head tube (ie it'll be just as tall), but a shorter top tube (i.e. it's a little shorter.)

I'd say your short torso would fit the best on the 19" WSD.

I think that you're borrowing trouble. Before you get all worried about sizing, go and test some bikes.

My "wingspan" is 6" longer than I am tall. Haven't checked my legs, but they're long as well. I ride a Surly LHT that fit like a glove straight out of the box (well, better, actually, because I have long fingers, too! Gloves are problematic for me). My LBS measured for pubic bone height and ordered the size indicated on the manufacturer's chart.

I'm another 50%-er with a wingspan 3" longer than my height, but only 5'4". I comfortably ride both WSD and non-WSD bikes. My bike size is generally (very generally speaking!) a size bigger than my height might indicate, but at least a couple sizes smaller than my inseam will allow. Clear as mud, right? ;)

The bottom line is that you, IMO, need to ride a bunch of bikes. Focus on how it feels, not the number on the tag.

I am 5'11, with 34-35 inch inseam. I am not sure of my arm length, but I think they are in proportion to my body. I bought a 20" men's 7.5 FX last year and it was fine for me. I test rode the 22.5" and I felt ok on it, but a bit out of control and it was definitely a challenge just to swing my leg over. I have a feeling that would be way too big for you. I don't know if this helps given how different my height is from you, but just thought I'd throw it out there. Good luck! (Can you get some kind of gift certificate for your points instead of an actual item, or cash applied to your Amex bill? Just trying to think of a way you could purchase directly from a store instead of through Amex.)

thanks everyone for the quick responses!
so I forgot to mention that my dad has the fx7.2, in 20". i haven't been on it for very long (it's the newest so someone else always calls dibs) but it seems to fit fine, trouble is, i wouldn't know the 'right' fit if it bit me on the tuchus. i didn't notice how badly the mangled toys-r-us bike fit until i hopped on my dad's bike and realized that didn't feel the need to standup constantly.

also, it's pretty sweet riding a bike where the gears don't 'pop' and send your feet flying off the petals every time you accelerate. so... yeah, that's what i've got to compare it to. though, i guess with the bar that low, any bike I get will be great. :D

in regards to trying out bikes at the shop... trouble is, our local bike shop doesn't really carry hybrids, just road bikes and cruisers. plus the owner is a total jerk. the nearest place that is willing to redeem an amex voucher is a bit of a drive, not a trip i want to make more than once. i suppose the best thing to do is to try and find another shop not too far which carries a brand which I can get from amex.

as far as trying to switch the points out for cash, i'll have to check in on that. i have a feeling they limit it to gift cards for box stores. i also have a suspicion that the exchange rate is not so great. plus, the voucher method keeps me from thinking about how much i'm spending on a bike. lol. (broke college student) but if that turns out to be an option, i might be able to save some dough by getting last year's bike.