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Roadbike size for me?(10 posts)

Roadbike size for me?Gunn
Mar 17, 2001 6:01 PM
For years, I have ridden mountain bikes off-road...and even on the street. Now, I want to actually buy a road bike to ride, well, on the road and save the mountain bike for the trails.

I'm 5'11" and own a 19" Specialized Rockhopper mountain bike. Based on that, what size of a road bike should I be looking for?

I'm not sure if the 19" translates into the right size in centimeters (about 48cm) for a street bike...if they take the same measurements in both. Also I've heard/read that you don't need as much -clearance- on a street bike so that number might go up. So should I possibly be looking in the 50-52cm range..or is this too small?

Thanks,
re: Roadbike size for me?pupmm
Mar 17, 2001 11:45 PM
i am 511 and i ride a 19.5 mountain bike and a 56c road bike with a straight top tube.with the road bike i have an inch or 2 clearance standover height.
re: Roadbike size for me?Dave Hickey
Mar 18, 2001 4:10 AM
Based on the info given, a 50-52cm bike will be way too small for you.
I'm 5'7" with a 30" inseam and I ride a 50cm bike. Also remember some roadbikes are measured center to center and others are measured center to top.
A general rule of thumb is you should have 1-3cm of clearance when standing over the top tube, however I feel the top tube measurement is more critical. My bikes all have a 52-53cm top tube. When I look for a new frame, I buy based on top tube length. Check out your local LBS and try various frames. Also www.excelsports.com has a good section on fit(I know their catalog does, I think their web site does also.)
re: Roadbike size for me?Dave Hickey
Mar 18, 2001 4:22 AM
Sorry, I meant to say 1-3 inch clearance when standing over the top tube.
not enough infoJack S
Mar 18, 2001 6:16 AM
Disregard what others have said, like I'm about your size and I ride a.... Your correct size will depend on your own body proportions. Go get fit by a shop- if you are shopping for a bike let them know that you have no idea what size and they will do some rudimentary measures to get you in the ballpark. BTW, to anwser your question, a 50-52 is likely WAY too small unless you have really short legs but if that were the case you would need a custom bike to get a propoer top tube length.
re: Roadbike size for me?Ian
Mar 18, 2001 6:35 AM
I will have to disagree with Jack S. about disregarding what others have said. He tells you to go to a LBS for a ballpark figure, well we can give you a ballpark figure here. Then go to a LBS for an exact figure.

The first thing you need to know is frame sizing. It is done one of three ways; center to center of top tube, center to top of top tube, center to top of seat tube.

I am 5'11" and would ride a 54 cm Specialized, they measure center to center. But the 5200 I owned was a 58 cm, Trek measures center to top of seat tube.

So there is your ballpark figure, probably around 54 cm to 58 cm.

Once you start loooking at bikes, pay attention to the top tube length. It is as important as seat tube length. Top tube is always measured center to center. Just pay attention to bikes you feel comfortable on and make notes on their measurements. With a little work you will get a bike that fits you correctly. Good luck.
re: Roadbike size for me?rich
Mar 18, 2001 2:59 PM
I'll vouch for the correct top tube length. Every bike I look at feels crampy up top for me. I'm 5'11" and have looked at bikes in the 56cm range. The stand over height seems correct. I'll stick to my 62cm for a while longer, it is so comfy and I can stretch out.
Try a fit formula ...bianchi boy
Mar 18, 2001 6:47 AM
Like the one on coloradocyclist.com website. BTW I am your height (5'11") but I am long-waisted with relatively short legs (80cm inseam). I also have a 19" Specialized mtb (Rockhopper). My current road bike is a Bianchi Alloro with a seat tube measuring 57 c-top or 54 c-t-c. The top tube is 56 cm c-t-c. According to the Colorado Cyclist formula, I should ride a bike with 53 cm seat tube, but that would leave me with too short a top tube. Many riders, myself included, feel that top tube is the more important measurement because it's more related to comfort. If top tube is too long you will be too stretched out, if too short you will be scrunched up.
Be precise - get fitKerry Irons
Mar 18, 2001 4:40 PM
Here are some good sites with fit calculators:

http://www.bsn.com/cycling/ergobike.html
http://www.coloradocyclist.com/BikeFit/index.cfm
http://www.sheldonbrown.com/harart-frames.html
http://www.electriciti.com/~bikelane/sizing.html
http://www.rivendellbicycles.com/frameinfo/Frame_Sizing.htm
http://www.peterwhitecycles.com/fitting.htm

After you've studied these a bit, then you will be prepared to have a worthwhile discussion with a bike shop. There is a risk at many an LBS that what they have just happens to be "perfect for you." If you've done your homework, that won't happen to you. Any comparison to your MTB frame size is very general, and your overall height is meaningless, because you need to take into account both your inseam and your torso/arm length. These sizing calculators will help you figure out how to measure yourself and then pick the right frame size. Note that several bikes might have the same seat tube length/standover height and yet have significantly different top tube lengths. Your upper body dimensions are important and will determine the proper top tube + stem length. Depending on the bike shop, you run the risk of getting fit by just checking whether you have enough clearance between your crotch and the top tube - NOT GOOD ENOUGH. Also recognize that as you adapt to road riding, you tend to stretch out on the bike, so if your chosen bike's stem is already long, when you go to a longer stem to accommodate your evolving position, you may find you have the wrong bike. Things to consider when you're looking at the results of the fit calculators and looking at any particular bike in a shop.
Be precise - get fitGunn
Mar 20, 2001 6:10 PM
Thanks all for your info and weblinks; I checked them all out, and got a lot of good measurements and calculations that I need to get a bike.

I'm actually steering towards the Giant bikes, which have a S-M-L and are adjustable in a certain range....seems that they are a bit more limited in sizing; or maybe with the adjustability, that can be easily taken care of. Anyway....thanks again,