Question about frame size

[stavros222]

I probably should have asked this question BEFORE I started buying bikes! Anyway, here goes......

How do you know what size frame and components fit you? People seem very exact when it comes to dimesions and I wonder whether it's down to experience, or is it written somewhere that if you're a certain height, with certain length arms/legs then you ride THIS size? An example would be 170mm cranks compared to 175mm. I can't imagine that 5mm would make THAT big a difference, but it obviously must do?

I've always just ridden bikes and if they are comfortable then great and if not, I sell them (unless I absolutely love them then I just put up with the bad back!). I've always thought that if they look like they fit (between 18"-20" for me at 6'2", then that'll do!). Unfortunately I think that smaller bikes look better, so i've probably been riding bikes that are too small for me for the last 15 years!

So, is there a science to it?? Please don't attack me for being ignorant!

Cheers!

 

[orange71]

the more I cycle the more particular I get about sizing. I know exactly what I need now probably to the nearest 5mm. I recently went on one of my bikes I hadn't been on for a while and it was terrible - it felt completely wrong. Needs revisiting with different stem etc!

Just keep trying different combinations till it feels right. There isn't a science because even if something 'fits' you, it may not suit your riding style. And even then, as I am finding out, my riding style is changing which means a change of dimensions :roll: ho hum... more bikes then!

 

[jango]

It's a tricky question.

Take your favourite, most comfortable bike and measure it......not just the seat tube, measure everything, the most important being the length of the frame ie top-tube length but also the effective top-tube length (measured horizontally) this should then give you a set of figures to work from when buying and then building a bike.

Good luck!

 

[FairfaxPat]

180mm cranks would be easy for you to use, unless you have really short legs at 6'2". I use them and am 6'1" with a 33" inseam. In the dirt, with RPM not nearly as critical as torque, the extra length makes quite a difference as long as you have long enough legs to accomodate the bigger circle you are pedaling. I have always preferred smaller frames on the road, with a long stem and seatpost to make them fit plus 175mm cranks for a faster spin rate. However, in the dirt I use large frames for better stability-especially downhill, as you fit farther behind the front axle with the longer top tube and wheelbase.