Frame size...what does it refer to?

mazcp

I was going to buy a bike on e-bay and the frame size is quoted as 55cm...what does that measurement refer to? I would've thought the most important measurement was distance from floor level to top tube, so you know you can straddle it easily...but it can't be this, cos the measurement would be way too small.
Any ideas? Thanks

giant_man

55cm sounds like the top tube measurement tho i could be wrong. Some framemakers go by the seat tube measurement and some by the top tube.

Try and get the other measurements on the geometry for that particular bike and go from there, relating it to your own bike.

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SIZE IS EVERYTHING! or at least that's what my LBS tells me.

monty_dogcp

55cm refers to the seat tube length, from the BB spindle to the where the top tube joins. Suggest you make a visit to your LBS and try a few bikes for size before you commit your readies. Also you'll find a few bike size calculators/website - worth googling a few to see what they say based on your height and key body dimensions.

Unknown

Usually as Monty D says. Some c b/b (axle spindle) to top of seat tube, some to centre of top tube where it meets seat tube and some to top of top tube where it meets seat tube! And for sloping top tube frames, some from c b/b to where top tube would be were it horizontal!

If doing ebay or similar, always best to ask "measured from where to where?".

d.j.
"Not much to see,
Not much left to lose"

mazcp

Thanks for the replies.

on the road

You might want to ask him whether the frame measurements are centre to centre or centre to top.

Down the Road

any frame can be described as anything using Seat tube length Vlassic example De Rosa Idol 64 cm is actually 55.5 cm long (Top Tube) Then you have to faqctor in geometry and the like to discover your perfect length.

If you don't know what size you need then don't buy off E-bay as you will most likely make an error.