Help deciphering frame size..

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TobyM

Senior Member
I emailed a seller on ebay about a bike, asking what size the frame was (why do they never say!?) and he replied with the following:


The crank is 19cm from center to edge.
The frame is 38cm from inside the frame just above the crank to inside the frame just below the saddle.
I am just over 6ft and it is slightly too small for me.



I was impressed with the fast reply, but I'm a bit confused about his measurements.. First of all, he's included crank size. Not sure why. Secondly, frame size of 38cm - he's obviously measured from the wrong bit (just above the crank as supposed to the middle of the bottom bracket).. So should I add 19 to 38 (57) or is that not likely to get the correct size either..?


I've come to the conclusion, by adding the 19 + 38 = 57 and from the fact it's a little bit too small for 'just over 6ft' that the frame size is about 56cm. What do you all think?


I will email him back shortly asking for correct frame measurements, I just want to see what you all think!
 
You need to add half the diameter of the bb shell plus the distance from the inside corner of the down tube and seat tube plus he distance from the inside of the top tube/ seat tube junction to the top of the seat tube.

So, 380mm plus (half of 40ishmm=) 20mm plus gawd knows what. The depth of a steel or of an aloonyman top tube? And how much seat tube is showing above the top tube??

My (alunimum) Rocky Mountain (mountain bike) has 355mm seat tube inside corner to inside corner dimension, but it also has a steeply sloping top tube and a lot of seat tube showing above the top tube. It's a nineteen and I'm 6'1".

But, after all that, actually it's the seat tube to head tube length ('effective' top tube) which is the crucial measurement for good bike fit.

The crank is a 170mm or 175 mm. Like all the rest. It's hard buying stuff from idiots people who don't know how to measure things.
 

screenman

Legendary Member
Sorry but just because the guy does not know much about cycles does not make him an idiot. Maybe you would like to re-read your post and think again.
 
OP
OP
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TobyM

Senior Member
Sorry but just because the guy does not know much about cycles does not make him an idiot. Maybe you would like to re-read your post and think again.
I agree, he seemed friendly and helpful to me, definitely not an idiot! Have now found out that the frame size is 58cm - too big for me!
 
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