Cervelo seat tube length anyone?

Triathlon Forum
1

I’ve been looking on the cervelo webpage and can’t find any values for seat tube lengths. What I have found is head tube lengths though. So (as an example I will take P2K 55) is the following logic correct?

@ 75deg top tube length = 571

@ 78deg top tube length = 540

So, difference is 31mm for 3deg difference, using a bit of trig. SIN 3deg = 31/seat tubt length = 573mm assuming head tube lengths are both measured at seat tube / head tube join.

But a seat tube length of 573mm for a 55 frame seems/is too much - it should be less than 55. Which is why I think I’ve done something wrong…it’s been a while since trig class :/.

Can anyone help with this? Just curious to know what the actual numbers are behind the ‘virtual’ sizes.

thx

tom

edit: i don’t own one which is why i’m asking. otherwise i would just go out and measure mine :)…

2

Tom,

the way you’re using trigonometrics is a little bit confusing … don’t forget sin is not a linear function, then you can’t say sin78-sin75=sin3 … ;-))

I think the top tube length aren’t accurate enough to calculate anything, as a little variation create a large difference in seat tube length … but I can help you :

the standover height is 776 mm, minus the wheel radius plus BB drop equal 496 mm, and with a average seat angle of 76°, you have a 51 cm seat tube … simple, isn’t it ?

I have a cervelo one (2002 model) with a 12 cm head tube, and the seat tube is nearly 50-51 cm long … so it’s reasonably accurate !

HTH

3

…in theory sin (angle) = opposite / hypotenuse should work. Which is what I tried but i guess you’re right in saying the values might not be accurate enough.

I like your method ;). Thanks for your help.

tom