Burke Wells

I've been looking around at so much bike measurement & fitting info on the web, measuring myself, and trying to determine whether my current bike is an appropriate fit, or if it might actually be too small for me. (And yet I'm still a bit confused & unsure... ) My LBS wants $150 for a fitting, and I just can't justify spending that kind of cash right now, especially just to find some basic answers to satisfy my ignorance & curiosity.

I'm 5'7" with a cycling inseam of 30". My bike's seat tube (center-to-center) measures 49cm, and the top tube (center-to-center) measures 54cm. It's my understanding that a bike's frame size is determined by the length of the seat tube, thus I would deduce that my bike is a size 49. But then again, I feel so ignorant on some of this stuff that I might be completely mistaken.

Overall, the bike feels ok, but when I'm going down a hill and try to tuck into a good aero position, I find myself feeling a bit cramped. I seem to have the desire to push my butt back farther past the seat as I'm leaning my torso down more, with hands in the drops. (kinda hard to explain, but maybe you know what I mean). My saddle is currently as far back on the rails as it will go, thus making me wonder if my aero "awkwardness" is due to the bike being too small, or either my position is just wrong on the bike.

Any advice is welcome and appreciated.

Burke

clfjmpr44

While I can't comment on the measurements, Iknow of two things that can help extend or shorten your torso on a bike. 1. Any idea how long your stem is? 2. Do you have a setback seatpost (post does not go straight into bottom of seat, there is a little curve backwards that connects to the seat)?
If you don't have a setback seatpost, that could help the situation. Also, if you find that your stem is 100mm or something, you can extend that to a 130MM, which will spread you a bit.

Fat Boy Biker

I am also 5'-7". I just bought a Bianchi that is a 55cm, but I have to admit there appears to be several different methods of bike measurement, depending on manfacture. What type of bike do you have? On my Bianchi, I had to have my stem replaced because I had to reach too far (my back was getting a little sore). The factory installed stem was 110mm, I had to install a 90mm. Hope this helps.

Steve

auburnrider

I am also 5' 7" with a 30" inseam. I have been riding a 51 cm bike for 20 years. When I purchased my first racing bike in 1985, the LBS shop owner did a great job of fitting it. I am currently riding a Lightspeed. I have done everything from racing (crits, roadraces, time trials) to double centuries. For me, 51 cm is the right size. If you plan riding a lot, I recommend getting professionally fitted.

Trsnrtr

I'm 5'7" with a true inseam of 30-5/8" measured crotch to floor. I was fitted a few times and it always came out roughly 53x53 c-c. Fortunately, this is fairly common frame geometry. The only bikes that never seemed to fit me were Treks.

Waldo

Also 5'7" with 30" inseam. I ride a 51-52 depending on manufacturer.
Your top tube length seems pretty consistent with what would be a good bet. Without information on the exact bike you have this is speculation, but if you have one of the newer compact/semi-compact frames, that would explain the shortness of the seat tube.
No real proper way to size you without seeing you-arm length, torso, length, flexibility, personal needs/desires, biomechanical issues, etc. are all things that tend to get somewhat neglected by certain online "fit" calculators.

Burke Wells

Unfortunately, nothing new, fancy, or very valuable here. My bike is a Raleigh R40 (Was probably new in '96 or '97. I bought it off of Ebay because it seemed like a decent "useable" size for me, and the guy was within driving distance, and it was only $127 ) I know it's far beneath what many others would want or have, but I'm having fun with what I've got currently, and it's tiding me over until I can eventually get something nicer.

I don't know much about stems & stem measurements, but my stem is shaped like a number "7", and measures about 90mm from center of handlebars to the back of the angled point of the stem (my apologies if that's a goofy description).

Would my 49cm seat tube mean that I'm riding a 49cm size bike?

Thanks,
Burke

clfjmpr44

If in fact you are riding a 90mm stem (on the short side), you can definitely go longer there, which might alleviate your problem. Check an LBS to see how long you should go. As for downplaying your ride...there is no reason to. There are people on this forum with $50 bikes and there are people with $5,000 bikes. Most of us fall somewhere inbetween. Besides that, it's a heck of a lot better than riding your couch.

lotek 

I'm 5'8" my primary ride is a 53cm frame and to
be honest its beginning to feel a bit cramped.
49cm frame for someone who is 5'7" sounds small
to me, unless you have unusually long torso and short
legs.
Trsnrtr, the reason Treks didn't fit you is that the lower
models are measured ctt and the top end models are
ctc. confusing I know.

Marty

Jose R

I'm 5' 7" ~135lbs

My custom road bike (Dean) is 49cm (c-c) which would be equal to a 51/52cm (c-t) depending on manufacturer. My TT length is 51.5cm with a 13cm stem. The distance between the front tip of the saddle to center of handlebars is 53cm. I use a setback seatpost. There is about 5-6 inches of seatpost showing. The fork rake is 4.4cm. The wheelbase is 96.5cm.

My new custom track bike (Andante) is 49cm (c-c). The TT length is a little under 53cm with a 11cm stem. With a setback seatpost the distance between tip of saddle and center of handlebars is 53cm. Same amount of seatpost showing. (I will be experimenting with a no-setback seatpost and 12cm stem.) The fork rake is 4.4cm. The wheelbase is 98.5cm. (Use is mostly for commuting, occassional velodrome.)

Most custom framebuilders will design a frameset around a TT length of Xcm and 12cm stem for proper reach. This allows for +- adjustments of 1cm without affecting steering and front end handling.

I would not ride a bike with a stem shorter than 11cm or longer than 13cm. This tells me the frame is either too big or too small or designed with the wrong geometry.

Once you go custom you never go back.

Trsnrtr

Yeah, I'm aware of that. My team had a Trek sponsorship in 1989 and 1990 and I couldn't seem to get a bike to fit. I think it had more to do with the angles than tube lengths. BTW, these were aluminum 2000 frames.

Burke Wells

Thanks for that. I guess it's just a bit intimidating to come up in here talking about my bike after reading much of what I've read by others. Kinda feels like showing up at an exotic car show with a '76 Pinto.

Thanks for all the comments, guys. I do appreciate all the thoughts and suggestions.

Burke

TCR

Cycleman1958

My moniker is "Shortlegs" for a reason. My inseam is 29. I am 5'7". My ancestral name from France is "Mon Petite" or little mountain. The Trek 52 cm was just a bit big, so I gave up on it. What worked was the Giant small frame, but I have no idea how big that is. 49 cm seems small to me for a guy with inch longer legs.

KirkeIsWaiting

I'm right there with you! Only I think mine's a VEGA!

I'm trying to sell myself on the 'vintage" bike thing being cool.
It worked for a while.
But it's like setting your clocks ahead a few minutes so that you're not late,
you can only fool yourself so long. (LONGER for me, I'm blonde!)
Maybe it's time for a new ride and fit, on a new ride or old, just makes all the difference in how many miles you can go without some sort of ache or ailment.
And right, we're not all driving M6's.

Al1943

No. c-t measurements are more common. Don't know about Raleigh.

Al1943

Nope, Treks are measured c-t including their high end frames, and the "t" means top of seat tube. Treks can be tricky to fit because their steep short head tube causes a lot of saddle to bar drop and long reach.
I still own a 5500 but with a short torso my body was not designed to fit a Trek.
Al

Dahon.Steve

I'm 5'7" and fitting depends on the manufacturer. My Bianchi Eros is a 53 and it's fine but my Jamis Aurora (touring bike) is a 54 and quite large. I've had to make adjustments and put the seat all the way forward for it to work. I test road a Lemond and it fit perfectly at 51! The LBS owner told me the next size would have been too big at my height. I also test rode a Trek 1200 at 54 and it fit very well! Go figure.

The Eros at 53 is fine, but it would be too small at 49cm which is why I didn't buy a bike that size. A traditional frame at 51 would be perfect. I might even try a 49cm frame but only if it's a traditional geometry.

Dave719

I'm 5'8" with a pants inseam of 30", but 31.5" from a bike fit. I ride a 54cm Spec Allez Comp w/ a 110mm stem. I have short legs, so my longer torso pushes me towards a larger frame so I can get a more suitable reach (actually thinking of going to a 120mm stem). Of course, this reduces standover, but that should be a secondary consideration.

A 49cm frame seems too small. A professional fit as others have said may be worth it.

Dave

lotek 

yup, the older treks (mid 80's early 90's) were measured 2 differnt ways.
The lower end frames were measure imperial (inches) and were CTT.
the higher end frames were metric and CTC
Don't know about the new OCLV but when trek was a
new company thats what they did.

Marty

audiojan

I'm 5'8", my tri bike is Kestrel Talon (52cm) and my road bike Giant TCR (Medium), both are using 80mm stems. The top tube is substantially longer on the Giant (virtual) 553mm versus 520mm on the Kestrel, but since one is setup for long distance comfort (Giant) and the other for max. efficiency in the aeroposition (Kestrel), the distance does vary.

In general, 49cm sounds very small for someone 5'7"... My wife is 5'2" and rides a 48cm Kestrel....

I would really recommend a professional fit for you... They may be able to make you comfortable on the smaller frame, or at least recommend what size you need.

Al1943

Well OCLV road bikes have been around 10 years and they are c-t.

Old and Slow

I am 5'6" and ride a 51 cm c-c with a 53 cm top tube and 9 cm stem. However, my cycling inseam (not pants inseam) is 31.5". So I have relatively long legs with a short torso, whereas at 5'7" and 30" cycling inseam, you are just the opposite. The Lemond formula for calculating c-c frame size is .65 times your cycling inseam, which works out to 49.5 cm for you.

You should make sure of your fore/aft saddle position by measuring the "knee over pedal spindle". (Just Google that term for an explanation) Also, you should be sure you are using the correct length stem. There are a couple of simple but crude tests for proper stem length.
1. In your normal riding position, with your hands on the hoods, the handlebar should block your view of the front axle.
2.Another rough (and I emphasize rough) estimate of stem length is this: With your elbow just touching the nose of your saddle your finger tips should just be able to touch your handlebar.

There is a good on line size calculator at https://www.coloradocyclist.com/bikefit/. Why don't you measure yourself and see what numbers the calculator gives?