Frame sizing technical help/advice needed

[Dr Imran T]

Hello chaps

I've just recently bought a new road frame size 56cm Centre to Top of seat tube. I am quite happy with the size of the seat tube but have a few concerns with the length of of the top tube.

Top tube length is 540.5 mm

I am a little over 6ft or 183.5 cm tall.

My other bike a cyclo-cross bike running a flat bar has a top tube length of 560.5mm and runs a 125mm stem and 54cm C-T seat tube.

I feel pretty comfortable with that set up however, this is with a flat bar. That said the reach is good and I like the top tube length.

My concern is that I may be slightly scrunched up on my new road bike.

I thought that I could fit a longer stem of say 135mm and perhaps a 10mm or 15mm setback seat post?

Would the drops help extend the outward reach?

I am not sure on whether I should just shift the bike on or go about getting the bits and trying it out.

What do you chaps think?

Thanks

[thiscocks]

As you say I think 54 is a bit small for 6ft, but might be ok with a long stem (120mm+). Personally id get a bigger frame (56 tt minimum)

Edited by thiscocks on Monday 24th December 22:26

[Gizmoish]

Sounds a smidge short ... My bike is 54cm effective top tube and I'm 5'9.

I assume it was a s/h frame?

[Dr Imran T]

Thanks chaps, that's my feeling too.

Not keen to try and make it fit by adding longer parts etc.

I'm suprised that a 56cm frame has this length of top tube.

Shame as the frame looks absolutely amazing.

Will return it and go for a min 56/57 top tube.

Thanks

[Dr Imran T]

Gizmoish said:

Sounds a smidge short ... My bike is 54cm effective top tube and I'm 5'9.

I assume it was a s/h frame?

Brand new. I can return it but really wanted to keep it.

[Gizmoish]

I'm surprised its that short too. TT bike?

[Dr Imran T]

^^You'd think so but nope. Pretty race 'like' geometry otherwise though.

Most 56cm frames have 560+ top tube some 575mm..

Depends on make I guess.

[LRdriver II]

Dr Imran T said:

Hello chaps

I've just recently bought a new road frame size 56cm Centre to Top of seat tube. I am quite happy with the size of the seat tube but have a few concerns with the length of of the top tube.

Top tube length is 540.5 mm

well, its C to Top of seat tube you say is 56cm, so this would mean roughly 54-55cm c-t-c toptube which fits with the top tube length.

sounds like you messed up the definitions and bought a size too small frame.

I look at effective top tube lengths as determining factor, as this cant be adjusted alot apart from stem lengths. Seat tube is useless as you just adjust seatpost to tweak it.

[Dr Imran T]

^^ You're kind of right. Although top tube length does vary with different bike manufacturers.

I was looking at a Giant TCR prior to buying my current frame and the top tube length was perfect for a 56cm frame.

However, I did break all the rules and bought the frame unseen.

Thanks

[Jimbo.]

Dr Imran T said:

Hello chaps

I've just recently bought a new road frame size 56cm Centre to Top of seat tube. I am quite happy with the size of the seat tube but have a few concerns with the length of of the top tube.

Top tube length is 540.5 mm

I am a little over 6ft or 183.5 cm tall.

My other bike a cyclo-cross bike running a flat bar has a top tube length of 560.5mm and runs a 125mm stem and 54cm C-T seat tube.

I feel pretty comfortable with that set up however, this is with a flat bar. That said the reach is good and I like the top tube length.

My concern is that I may be slightly scrunched up on my new road bike.

I thought that I could fit a longer stem of say 135mm and perhaps a 10mm or 15mm setback seat post?

Would the drops help extend the outward reach?

I am not sure on whether I should just shift the bike on or go about getting the bits and trying it out.

What do you chaps think?

Thanks

You may've gone a bit short/small. I'm a shortarse at 5'7" 1/2 (remember the half, dammit!) and 545mm is the kind of effective TT length I'd look for in a roadbike. HOWEVER, everyone's different, so YMMV

[Dr Imran T]

Thanks for all the advice chaps. I'm going to return or sell the frame on.

I guess there is only so far you go with add on bits to get a good fit.

Best start with the right size frame and then finely tune the add on bits to get the 'perfect' fit.

Cheers