How much does size matter?

[hilaryworton]

I'm getting back into road bikes after suffering for several years away on mountain bikes. I've been trying to do my research on brands/models etc but have got completely baffled by information overload. Can anyone give me some simple advice on 2 basic questions? Firstly how to decide what size to buy? One shop is trying to get me on to a 46cm and another is adamant I need a 50cm. I'm 5'7" (170cm). I've tested a couple of the smaller size bikes which felt OK (but what do I know as it's been so long since I've riden a road bike). My 2nd question is whether to go with a double or a triple? Again, it seems to depend who you talk to (and what stock they are trying to shift - or am I being too cynical?) I need all the help I can get on the uphill parts of a ride and thought that a triple would be the way to go but I've also been told that a compact double would be just as effective. Any ideas to assist the bemused would be gratefully received!

 

[weedvspeed]

Are they the same model of bike? There can be a large difference if one is a compact/semi compact frame (sloping top tube) or a traditional one. Also some manufactures measure the frame to the top of the seat tube some to the top tube.

Calculators are not perfect but this site gives a lot of info on fit and what all the geometry means. You can always ignore the results for what feels best.
http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO
Cant advise you on the triple its flat where I live.
Good luck

Weed.

 

[hilaryworton]

Thanks for your advice. I've been out again today looking at bikes and have found exactly as you say that different manufacturers size the frames from different points. I actually found a bikesizing.com facility where they measured all the critical parts of my anatomy eek: ) and so now I have a print out of my own geometry which I can use to match against the bikes I'm looking at so hopefully that should help demystify some of the decisions. Fingers crossed...

 

[ibis1]

triple or double?


what kind of terrain will you be riding on? and how old are you?

i live in a hilly/mountainous area, and i'm over 50 so a triple is important. i even went further and changed my rings to 48,38,26 (typically they are 52,39,30) so i could get up the 22% grades with bad knees.
if you are young and in flat terrain, a double will do. the compact double gives you a 34 as the small ring, so it is a compromise between the two..

 

[dw_moto]

I think you should go out and get custom bicycle fitting. I suggest this for anyone looking for a new bike. It will cost about $100 but they will set up a bike perfectly for you. You will not only know what size bike you need but where you saddle needs to be set, if you need a women's specific bike, crank length and the handlebar stem length. Most women need narrower handlebars and a shorter crank. If you know this when you get the bike you can usually get the parts exchanged at little to no cost.