Road Cycling - please explain the disadvantage(s) of a frame 2cm too small

At 6 feet tall I have been told that my frame size is 58cm. However, a frame that I am interested in acquiring is 56cm. What would the problem be if I just raised the seat a little? I will turn this frame into a "frankenbike" by adding bmx handlebars. I am primarily interested in combfort as this will be strictly a commuting bike. I am more interested in being combfortable in a upright position than bent over for areo dynamincs. Also, I have some problems with my neck that I get adjusted every month at my chiropractor; so long periods bent over handle bars may aggravate my neck problem. What are the disadvantages to have a frame 2cm too small? I know that bike "fit" is very important, but does this apply in my situation given the bmx bars etc?

Have you had the chance to ride a 56? That doesn't seem like a problematic size for a 6 FT tall person. I'm 5.95 and a 56 was way too big for me. Also, as already mentioned many times before, one frame maker's 56 is different from another's. Therefore, test-ride the bike you're considering. If it feels right, then it probably is right. If you feel scrunched, then it's too small. I ride a 54" frame currently. Even the 54" is somewhat biggish. I could go down to a 53. But, I've always ridden big frames for some reason. The general rule is you're better off going down in size, rather than riding a frame that's slightly too big. That's what I've heard anyhow.

Steve

Vegan,

How much 2cm will have??? For the type of riding you plan to do, sounds like you need a "tour" bike vs a racer if that's what you were thinking.

Check out this sites. Very informative. If there you don't find any answers, use google's search engine.

Good luck.


http://www.triathlonacademy.com/articles/lymanbikefit101.asp

http://www.caree.org/bike101helpfulhints.htm

http://www.caree.org/bike101backpain.htm

http://www.tmbra.org/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=forum&f=6

I can't test ride the bike because I am buying a frame which I will build up using components from my current bike. The frame is a Paramount OS and it has eyelits for the front and rear racks etc. It is a road frame. I am assuming a road frame will be lighter than a touring frame. Its made from Tange steel. Does anybody know any websites describing this steel?
Thanks for your posts!

Check out his site. Also... if you need his help, email him.
http://sheldonbrown.com/



Originally posted by veganheart
I can't test ride the bike because I am buying a frame which I will build up using components from my current bike. The frame is a Paramount OS and it has eyelits for the front and rear racks etc. It is a road frame. I am assuming a road frame will be lighter than a touring frame. Its made from Tange steel. Does anybody know any websites describing this steel?
Thanks for your posts!

a 58cm bike can mean different things. i see spec's for 58cm bikes with 57.5cm top tube measurements. i see 58cm bikes with 59cm downtube measures.

measured center to center my 58cm is exactly 58cm TT and 58cm DT but that is an anomoly.

56cm from what? The bottom bracket height also affects the standover clearance.
Once you are on the bike, standover is irrelevant, but a smaller frame will have shorter headtube. You will be able to position the bars lower for aerodynamics (which you apparently dont want to do). You may end up riding with an excessive amount of stem rise. You may be better off with a longer head-tube . If using a threadless steerer, so ensure that you have a long length of uncut steerer for a high bar position.
Smaller frames are usually shorter. How does the top tube compare to your current setup. You may benefit from a shorter TT to achieve a more upright position.

when is a good deal NOT a good deal?

when the frame doesn't fit

Mercxrider- You must have a really short inseam length if your just shy of 6' and riding a 54cm. I'm 6' exactly and ride a 57cm Lemond (which is measured CtoC so fits like a larger bike from many other makers)


Normally I would say that this frame is too small for you, however, considering what your planning to do with it I doubt it will make much difference. Having a shorter tob tube will actually probably help, and the rest of it can be made to work just fine since your not actually going for a traditional position on the bike.

The key to this discussion is that height is not the important indicator of frame size. If you have long legs for your height, you'll be more comfortable on a different bike than if you have short legs for your height.

That said, I think that a long-ish steer tube/riser bar and stem will keep you from having any major problems should the frame be too small for your inseam. If you were ever going to turn it into a road bike with drop bars, a too small frame makes life miserable. You'll end up with the seat eight feet higher than the bars, and you won't feel your family jewels for weeks at a time.

Originally posted by veganheart
At 6 feet tall I have been told that my frame size is 58cm. However, a frame that I am interested in acquiring is 56cm. What would the problem be if I just raised the seat a little? I will turn this frame into a "frankenbike" by adding bmx handlebars. I am primarily interested in combfort as this will be strictly a commuting bike. I am more interested in being combfortable in a upright position than bent over for areo dynamincs. Also, I have some problems with my neck that I get adjusted every month at my chiropractor; so long periods bent over handle bars may aggravate my neck problem. What are the disadvantages to have a frame 2cm too small? I know that bike "fit" is very important, but does this apply in my situation given the bmx bars etc?

uhh.... i hope you are talking about mountain bike handlebars, not BMX bars.

Also, you're going to need to buy special stuff if you want to build up your frame with an MTB-style flat bar. If you look at Shimano's website you will see they have special shifters and brake levers designed for use with their road gruppos. You can't use the regular STI levers on an MTB handlebar, let alone a BMX one!

THIS is a BMX handlebar:

This is a mountain bar

and i know what you're trying to attempt (buying a frame just based on the declared seat tube length).... and i oh-so-highly reccomend against it. You don't want to buy a frame, build it up, and THEN find out that it doesn't fit you.

Spend some time researching bike geometries... test ride some bikes at bike shops. It will give you a "feel" of what frame size you need for each manufacturer. For example, I now know that I need a 50cm speciazlized, 50 cm Cannondale, 54cm Trek.

If you're gonna build it up without trying on the frame for size first, find yourself a bike that fits you well, find its geometry specs, and then pick a frame that gets as close to those geometry specs as possible.

Finally, I know it must be really annoying that I am repeating the same advice over and over again... but please understand that I'm trying to be helpful here.

I am not a road bicycle purist. I get creative, so yes I AM USING BMX BARS. On my cannondale, before it got stolen, I had bar ends on a traditional mtn bar. I found that besides the time I was breaking or changing gears I was on the bar ends. I am using bmx bars because i can put the shifters and brake levers right where my hands are which is somewhat safer and more convenient. I know i am losing some steering control, but it isnt so much that i feel it is unsafe. my current bike has bmx bars and it is really combfortable for me and the steering isnt that affected in my opinion. I ended up getting this 56cm paramount frame for free so I am definitely going to build it. I am pretty sure it suit my purposes fine. If it doesnt work out... oh well all it cost me was time. The bike shop originally charged me $100 for the frame, but then they found the bb was seized and they spent a considerable effort trying to get it out. They were unsuccessful. The refunded my money and said they were going to throw the frame in the garbage. I asked If i could have the frame since they were going to throw it out anyway. When I got it home it only took about 15 min to get the bb out. I used a hacksaw, hammer and screwdriver and "peeled" the bb out. Sometimes thinking outside the box is advantageous!
Anyway thanks for all your advice.

ok well if it's free, you've got nothing to lose... go for it! :)

If the frame is too small, that is more stress on the seatpost. If the seatpost snaps and you sit on it, you'll be in a world of hurt.

[QUOTE]Originally posted by slide13
[B]Mercxrider- You must have a really short inseam length if your just shy of 6' and riding a 54cm. I'm 6' exactly and ride a 57cm Lemond (which is measured CtoC so fits like a larger bike from many other makers)


Hi again,

I think you misread my post. I am 5 feet nine and a half inches tall...I'm not sure if that's "just shy" of 6ft. I often get accused by my 6ft tall friends that I'm a "short shot of whiskey". I have a 31 in. inseam and the 54" in. frame I'm riding seems to be a perfect fit. I do believe frame sizes can vary dramatically, depending on the manufacturer and material. I also have an old Fuji steel frame that's a 57 and that too seemed to feel right. I put about 12,000 miles on that bike, so go figure. ;)