What size frame do you have?

[jobob]

Frames vary a lot, in geometry, bottom bracket placement, you name it.

So don't automatically assume that if you fit on a X size frame from one manufacturer, the size X frame from another manufacturer will fit.

It's a lot like buying jeans. I wear a size 10 in some brands of jeans, but I had the happy experience recently of trying on another brand in size 10 and I couldn't even pull them up over my butt.

[mlove]

My Trek Hybrid is a 14. I just got fitted so I can get a Pilot and I fit between a 47 and 50. I tried the 50 and it was great.

[SadieKate]

Frames vary a lot, in geometry, bottom bracket placement, you name it.

So don't automatically assume that if you fit on a X size frame from one manufacturer, the size X frame from another manufacturer will fit.

Well said, Jo!

If you're a complete newbie to buying bikes, get a professional to help. There are so many measurements plus musculoskeletal issues (such as how flexible and where you flex) that must be accounted for. Don't depend on numbers alone.

The labeled sizes I ride for both mtb and road are all over the ballpark -- it's just an arbitrary label used by the builder.

[Eden]

Bodies and frames vary a lot. I'm shorter than most of you at only 5', but I have a 29" inseam, which seems closer to some of you that are a lot taller. Even so I still ride a very small bike, since I need the really short top tube. My 700c road bike is a 44cm and the 650c frame I'm getting is a 47cm, the 650c TT bike I picked is a 48, but has the shortest top tube of all my bikes (yes I'm starting to feel like I might have too many...).