bike fit dilemma...

henderson_mk

folks,
need a bit of advice around bike fit.... thinking of getting a new frame, but am conflicted on sizing between a 56 and a 58.

Basically the numbers are like this (the 56 and 58 are the geometry for the potential new frame and the others are my existing bikes) :

frame size 56 58 planet - x 52(L) giant tcr 2 L
seat tube length 550 570 520 55.5
top tube length 554 565 570 58.5
head tube length 160 170 165 175
head tube angle 73 73.5 73 73.5
seat tube angle 74 73.5 73 73
chainstay length 405 410
wheel base 984 993 1009 1000
stem ? ? 900 1000

to my eyes, the 58 looks not a bad fit, but the seat tube is a bit taller than what I normally ride. ( I ride with a lot of seatpin showing). The 56 seems not bad either, but the top tube length is a little shorter.

I seem to be falling in the gap between the two sizes and either would do with a little tinkering with stem length / seatpost height.... would that be right?

Any thoughts anyone?

giant_man

And what size are you, height and leg size that is? Depending on your size, and the fact that you like a lot of seatpost showing (don't we all) the 56 might be your size.

This is all of couse without you being measured for that frame of course.

henderson_mk

i'm about 180cm tall,
leg size in trousers is 34 inches.. so about 86cm
I do have longish arms too.

(how can you do tables in this thing..? )

gkerr4

I'd go for the 56 and look for a slightly longer stem - 120mm stem should make up the difference and not affect steering.

henderson_mk

...how'd I know you were going to say that? :-)

for arguements sake... say I set the 58 up with a 90mm stem, would the fit be substantially different do you think? obviously the saddle would be a bit lower..

and finally.... would it make a difference if the 58 was 200 notes cheaper?

onebigrob

I am having the same problem. I’m thinking of going for a ribble nero (something) but I’m unsure about the frame size. So I call ribble… The guy on the phone said that I should get a large frame (the sizes go S, M, L, XL, XXL) which works out to be 54-56 apparently and is for people between 5’10 and 6 foot. Whereas the Medium is 52-54 and for people between 5’8 and 5’10. Logic would suggest that I need the large one as I’m 5’11. I’ve tried out a Trek Madone and I was a 54 on that apparently. Would there be much in the size difference or could I just get a smaller stem if the reach is too far? Not sure if it is safe to go for one too small or potentially too big. Any advice??

henderson_mk

melts your head this stuff doesn't it? :-)

its a fairly large investment and you just don't want to get it wrong.... for me it seems the main difference is that the seattube is about 1-5-2cm taller...
I ride with a lot of seatpost out as seen here... http://farm4.static.flickr.com/3023/256 ... 7324_b.jpg don't know that taking that down by 1.5-2 cm is going to make a lot of difference looks / fit wise...


onebigrob - the geometry on the ribble and the trek are probably a bit different so I don't know if its going to be possible for you to compare.
going by the sizing you state... sounds to me like you're a large with a short-ish stem

check out http://www.competitivecyclist.com/za/CC ... ATOR_INTRO maybe it might help too?

giant_man

God I do love your TCR Marty which I've said before. it's just FAB ......

henderson_mk

cheers my man