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I am a mutant? 5'7" and 31" inseam. Frame sizes. Help a n00b(24 posts)

I am a mutant? 5'7" and 31" inseam. Frame sizes. Help a n00bEug
Jul 10, 2002 9:49 AM
Just wondering what the average height to leg-length ratio is. I know the average changes with height and everyone is different, but nonetheless I want to know, just out of interest's sake.

I have a 31" inseam, but I'm only 5'7" tall.

Anyways, the reason I got onto this topic is that people are telling me my frame is slightly too big. This may be true, as I have purchased a Trek 2000 54 cm. The calculators online suggest I need a 53 cm frame, but this number seems meaningless to me. My Trek 2000 54 cm gives me about an inch standover with shoes on (spec'd standover is 30.3"). (My trusty tape measure tells me the 54 cm is to the top of the seat tube on that bike, and the seat tube top is several cms higher than the top tube.) However, judging by the Cannondale website, I'd be riding something in the 50-52 cm range.

By the way, anybody this height using 167.5 mm cranks? I have 170 mm on this bike, which is the same as my mountain bike - 175 mm destroys my knees.
Custom, Custom, Custom, etc...miposy
Jul 10, 2002 9:56 AM
You MUST buy a custom frame, and with it a custom build.

Strong Frames is a great custom builder. See them at

There are other good builders in North America as well.

Good luck!
Custom, Custom, Custom, etc...Eug
Jul 10, 2002 10:22 AM
Ouch. Thanks, but a custom frame from that place costs 25% more than my entire bike. Can't afford to spend that kind of dough right now.
don't agree...C-40
Jul 10, 2002 2:05 PM
5'-7" with a 31 inch inseam isn't necessarily extreme enough to warrant a custom frame.

Other factors such as femur length and optimum KOP position must also be considered.

FWIW, I'm 5'-7" tall with a long 83cm (32-5/8 inch) inseam. I get a great fit from most stock 54-55cm frames (measured c-t).

A compact frame like the Litespeed Siena (53cm) might be just the ticket. Plenty of standover clearance and enough top tube length to avoid an excessively long stem.
totally agree with youJohnG
Jul 10, 2002 5:08 PM

I'm a mutant too....tronracer
Jul 10, 2002 9:59 AM
5'8" w/ a 31" inseam. Is it tough finding pants that look good or what?!??! I'd go a little smaller. I have a 52cm older de rosa road bike, a 53 c-t bianchi pista track bike and a 17" Vicious cycles mountain bike. I love the fit on all of them.

I use 170 on the road bike and found out they are too small. The guy at the lbs said I have a short femur.
re: I am a mutant? 5'7" and 31" inseam. Frame sizes. Help a n00bjaybird
Jul 10, 2002 10:17 AM
You might want to take a look at some of the Womens specifc designs. They are generally shorter in the top tube relative to the seattube. Lemond has them and they dont say anything on the bike about it being sized for a woman. I can't remember if the the treks have a "WSD" printed on them somewhere. I know the Cannonwhales have femminin or something like that on them...

stay with the 170s you wont notice that much difference.
Is that a pants inseam or cycling inseam?jtolleson
Jul 10, 2002 10:19 AM
I'm assuming a pants inseam, because there's nothing mutant about a 31" cycling inseam on a rider that is 5'7" ... I'm 5'7" and my cycling inseam is 31.75" ...

I'm trying to understand exactly what you are describing.
Underwear inseam.Eug
Jul 10, 2002 10:27 AM
The 31" is the inseam measurement I get by cramming a book up my crotch while wearing briefs and no shoes.

If 31" isn't that unusual I guess it was the messages I was reading that had unusual sizing (like 30" inseams on 5'10" riders).
For me.....tronracer
Jul 10, 2002 11:08 AM
When I said mutant I was refering to my super human abilities. But, that measurement is the cycling inseam. I am 5'8" and 31" from floor to crotch. I did the book and tape measure thing a few times and 31" seemed pretty consistent. I have a short femur though so I need small pedals to get the kops.
I am 5' 9" with a 32" inseam (pants).MisJG
Jul 10, 2002 10:29 AM
It seems to me you're saying I'm a mutant too. My C-dale 54cm is a great fit. I don't know what you're talking about.
SHould have gotten a 52 Trek.elviento
Jul 10, 2002 10:30 AM
Roberto Heras and Livi Liphimer are both 5'7"-5'8". Both use a 52 Trek.
Hmmm... 16.5" mountain bike = 52-54 cm road frame.Eug
Jul 10, 2002 10:53 AM
Yeah, that's what I figured.

Oh well. I guess I'll rationalize by saying as a n00b I like the slightly lower seat (in relation to the handlebars). Not as aggressive, but I'm pretty recreational anyway - outa shape. Better luck next time I guess for me.

Anyways, assuming my 16.5" Trek mountain bike is correctly sized, using the online formulas I'm supposed to have a 52-54 cm road frame.

16.5" = 42 cm
42 cm + 10-12 cm = 52-54 cm

Anyways, I think I would have been better off waiting for the 2003 Thin Blue Line 53 cm Lightening 105 setup for CAD$1500 (US$985 for steel frame/carbon fork and everything 105) instead of this Trek 2000 2002 54 cm for CAD$1479 (US$970 for aluminum/carbon fork and 105/Tiagra). But I wanted the bike NOW!
I'm 5'7", and have a 30" inseamsharkey
Jul 10, 2002 10:42 AM
I think you will find a very nice fit on a Lemond bike (specifically the 51cm size -with a 53cm top tube). IMO You should stay away from bikes with "European" geometry, as they tend to have shorter top tubes -- exactly the opposite of what your long-torsoed self needs!

Oh yeah, forget the online sizing stuff . . . look for a local bike shop with a fit-machine (serotta has a great system), and get a professional fit done. It will cost around $40, and is ABSOLUTELY the best money you can spend -- especially if you're someone who can't get an "off the rack" fit.

I think the 170 cranks are a good length for you . . . that's what I use.

Good luck!!!
51 cm Lemond has same standover as Trek 54 cm...Eug
Jul 10, 2002 11:06 AM
...but a 1.6 cm shorter top tube (if the top tube lengths can be compared), and longer stem.

I am assuming the 51 cm on the Lemond is c-c, which does seem correct judging by the picture:

This would make sense, since the Trek 54 cm is only about 51 cm when measuring c-c.

The cranks are longer on the Lemond though.
I'm 5'7", and have a 30" inseamMP
Jul 10, 2002 2:49 PM
You have it backwards. This guy has a short torso, and relatively long legs. The last thing he needs is a Lemond. He would be better off with a compact frame.
re: I am a mutant? 5'7" and 31" inseam. Frame sizes. Help a n00bNo_sprint
Jul 10, 2002 11:20 AM
I agree with most others here. You might be more comfortable and better fit on a smaller bike. 5'8" here with slightly shortish legs. I ride 51s and 52s most comfortably.
5'8"-30.5" riding a 54cm 5200=1-2cm too longQuack
Jul 10, 2002 12:01 PM
I would say the 52cm Trek would be a better fit. I have wished that I bought the 52 ever since taking delivery of the 54. The 54 already has an extremely short stem so I either buy a 52 or slide the seat forward.
5'9 with 33.5bear
Jul 10, 2002 4:18 PM
I am only 5'9 but have a 33.5 inseam. my first bike was 54 and it never felt right! I got as 52 and it fits like a glove comprare to the 54. I need go by the top tube lenth because my inseam is too long for my torso and I was so unconfortable tryingto reach on a 55 top tube on my size 54.
I could never go in the drops on my 54 because it was just too far to reach.
Trek's 54 cm: c-c = 50.5 cm, c-t = 52 cmEug
Jul 10, 2002 4:21 PM
OK, thanks for all the replies. One thing that has been re-emphasized to me is Trek's sizing being different that many people's.

As I mentioned before, going by my tape measure, the 54 cm is from the spindle to the top of the seat collar. However, the c-t measurement is 52 cm, and the c-c measurement is approx. 50.7 cm.

Somebody mentioned that Roberto Heras (5'7" - 5'8") rides a Trek 52. I wonder if that's in Trek terms or it's a c-t measurement.
OCLV only...jtolleson
Jul 10, 2002 5:56 PM
to make it even more confusing. Trek only measures its OCLV bikes to top of seatpost collar. Weird. The AL Trek bikes are measured c-c, which is why you'll ride a "bigger" OCLV than, say, a 2300.
I measured an aluminum Trek. 54 cm = 50.5ish c-c.Eug
Jul 10, 2002 6:44 PM
Not just their OCLV bikes are measured to the top of the seatpost collar.

It was an aluminum Trek 2000 I measured. Their 54 cm equals approx a 52 cm c-t frame, but with a longish top tube (54.8 cm).

The c-c would be only 50.5 - 51 cm.
re: I am a mutant? 5'7" and 31" inseam. Frame sizes. Help a n00bdasho
Jul 10, 2002 4:27 PM
I am 5'7" tall with a 30" inseam and bought a 54cm Trek 5200 3 years ago. I probably should have gotten the 52 cm not so much for standover but because the top tube was a bit long for me. I am now riding on a 50cm (c-c) bike and feel much more comfortable. It's a tough lesson to learn but don't despair because you can change the stem length and angle among other things to get a better fit.
VERY normal geometryJohnG
Jul 10, 2002 5:07 PM
Your body #'s look pretty normal actually. You should fit just fine on most 52-53 cm frames.

The Trek 54cm frame is a bit small so it will fit like a 53cm frame.