Bike Sizing

portland_bill Posts: 287
edited June 2011 in Road beginners
Can anyone advise or is there a good place to look for guidance with sizing for buying a road bike?

Thing is, I don't really want to go and speak to my LBS because I can't afford to buy a bike from him and I just feel like I'm using him for info then buying cheap off the internet.

I can't afford to buy a new bike full stop, I need to look at a half decent second hand bike, but I'm struggling to find any concrete or sturdy info on sizing.

I'm 5'8" with a 29-30" inside leg and weigh far too much! :roll:

I'm more used to MTBs, so possibly not looking at a geometry that's too aggressive, but I don't want a tourer.

Any tips?


  • FoldingJoe
    FoldingJoe Posts: 1,327
    If you jump onto most manufacturers websites they should give you an indication of how to fit yourself, all be it fairly crudely, for one of their bikes.

    My legs are the same length as yours, 30", but I'm 5'10", so have a longer Torso.

    I went with a frame size on my Ribble (52cm) that fitted my leg size, but find that maybe the Top Tube is a little short for me.

    I'd guess that something around that size would suit you fine.
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  • going by that i'd say a 54-56cm frame size.
  • CRAIGO5000
    CRAIGO5000 Posts: 697
    Be careful though.

    I'm 5'10'' with a 33inch in-seam (more important than height) and most guides put me on a Large frame or 56cm. That guide above puts me at a ridiculous 58-60cm frame!

    I bought a 54cm and with it's massive 130mm stem, it feels too stretched out! I need to buy a 110mm stem to correct my stretching. There is plenty of room to raise the saddle more too and it's a cheap fix to get the correct length stem too.

    your best bet is to try before you buy. Personally I'd prefer to be on the larger side of a smaller frame than small on a larger frame.
    Ribble Stealth/SRAM Force
    2007 Specialized Allez (Double) FCN - 3
  • Cheers guys, all helpful info.

    I know the easiest thing to do is just to go and see the guy at the LBS, but like I say, I just feel like I'm mugging him off if I do that.

    I was actually thinking of going to see him and see if I can hire a bike from him to do the C2C and see how I get on with that. At least he'd be getting something out of it then, but I'm not sure if they still do that. Worth checking though.
  • thegreatdivide
    thegreatdivide Posts: 5,807
    I'm 5' 7.5", have a 29" inside leg and I ride a 52"/small frame (Wilier Izoard and Cento Uno).

    When I got back into road bikes I was sold a medium sized Specialized Allez Sport but I was way to stretched out and even with the pronounced top tube curve I felt uncomfortable standing over it. Put that down to shxt shop staff and me eager to get a bike. Ended up taking it back and getting the next size down.
  • Sounds like it's definitely going to be worth while trying a couple out at the shop then eh..... :?
  • navrig
    navrig Posts: 1,352
    Go and see your LBS. He may be able to source a suitable 2nd hand biuke. Afterall he'll know who is upgrading and some folks even ask their LBS to advertise their old bike.
  • cyberknight
    cyberknight Posts: 1,238 ... ATOR_INTRO

    When you know what measurements you have to look for you can start to compare the geometries of bikes you like.

    As long as the bike has the seat post range for your leg it is the top tube measurement that is the most critical to get a good bike fit, if it is too long or too short even fiddling about with stems etc etc is not going to help much.

    I ride 52- 54 (max) with a 100 mm stem , i once bought a 56 cheap and even though i had a short stem and the seat rammed all the way forward i still got back ache as i was overreaching.

    Best thing to do once you have an idea is try first if you can .
    FCN 3/5/9
  • MichaelW
    MichaelW Posts: 2,164
    The most critical dimension for fit is length from saddle to bars. Most modern bikes have plenty of adjustment in height.
    Some of the fit calculators make assumptions about how you want to ride the bike, eg in an aggressive racing style.
    The best advice I have found regarding bike fit is from Peter White Cycles.
  • RowCycle
    RowCycle Posts: 367
    If you feel guilty about going to your lbs, how about go to another town and another bike shop to get advice? Then you're not going to feel guilty when you go to your lbs to get it serviced :D

    Seriously though, a decent lbs should be happy to give advice, as chances are even if you don't buy a bike from them, you'll go their for a service or something, so they will still get your business even if not from a bike sale.