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The right size of bike

Peddle Up!Peddle Up! Posts: 2,040
edited September 2010 in Road beginners
I raised the question of bike size at the end of a previous thread, but I thought it might usefully make a new thread.

When I checked out my bike frame size recently it came out at 52cm (centre of bottom bracket to top of top tube from a dropped vertical line). I'm 6'3" with an inside leg measurement of 34" and just about every sizing guide that I've looked at suggests at least a 58cm (or larger) frame.

After some more research I realised that I should have measured along the diagonal from the bottom bracket to the point where the seat tube enters the frame (as demonstrated in this video), and this comes out at 54cm.

However, for either measurement the consensus from the responses to the original post is that my bike is too small.

I'm interested to learn what effects might follow from riding a smaller bike. I have compensated by having a high seat post, but would this influence bike stability?

How do I ensure that my next bike is correctly sized?
Purveyor of "up" :)


  • seems small, I'm 5'8" and ride 54cm bikes. My brother is 6' something and when he's on it, can tell it's way too small.
    Say... That's a nice bike..
    Trax T700 with Lew Racing Pro VT-1 ;-)
  • danowatdanowat Posts: 2,877
    Peddle Up! wrote:
    How do I ensure that my next bike is correctly sized?

    Buy from a shop that can offer you a fitment service?

    I am about your height, and I ride a 58, but thats not to say YOU need a 58
  • ScrumpleScrumple Posts: 2,666
    Don't most frame sizes correspond to the top tube??
  • I had to choose between 51cm & 54cm and went with 51cm, and i'm 5'7" with 29" inside leg. I'd have thought 6'3" would correspond to a 57cm or 60cm frame.
  • StillGoingStillGoing Posts: 5,207
    From my looking at various options for an upgrade there's a world of difference between manufacturers. The seat tube length isn't necessarily the only measurement you need to consider; your reach to the bars is just as important. I'm realising fast that a proper fitting service is needed.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • Very difficult nowadays to compare different makes of bikes in relation to quoted seat tube length. The only way is to physically sit on each bike to see if it's right for your height/reach and feels comfortable or if you have no previous road cycling experience go to a shop that provides a bike fit service.
  • Peddle Up!Peddle Up! Posts: 2,040
    It sounds like I need to visit a bike shop that has a good range of the best bikes, in different sizes, that is happy to let me ride a few of them. Has anyone managed to find such a place, or its it a case of visiting loads of outlets and making the most of what they have?

    Editied to add an additional thought...

    I've been reading the posts on a full bike fit - defo something to take up with a new bike. My question is, is it possible to get an independent assessment on bike size before buying? I'm a bit depressed to read about "10 minute assessments" in some shops. That smacks of selling the stock we need to shift!
    Purveyor of "up" :)
  • keef66keef66 Posts: 13,286
    I can only comment on my experience at Epic Cycles. I was there for over 3 hours being measured, fitted and test riding. And I came away having ordered a bike that fitted me properly and met all my requirements. The fitting was included in the price.

    Great service!
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