New bike, sizing quandary

dimmock_g

Now I know the obvious answer is to sit/try a model out but alas at the moment that's simply not possible

I currently ride a tcr advanced 1 in a medium and would like either a defy advanced 1 or potentially a roubaix

I'm 5ft 7.5" with a 29.5" inseam

On the TCR I've changed the stem to a 90mm and put all spacers under the stem to get the best feel/handling for me

Looking at the geometry of both the above I'm a little confused as what would be more suitable.

The m defy ticks all the boxes until I get to standover height - it has a higher standover height than my tcr, so then I'd potentially revert to a small

Looking at the roubaix, I'm thinking a 54 but cannot find standover anywhere - yet everything else points toward a 54

Any input or suggestions welcome

Cheers

arlowood

dimmock_g said:

The m defy ticks all the boxes until I get to standover height - it has a higher standover height than my tcr, so then I'd potentially revert to a small

Looking at the roubaix, I'm thinking a 54 but cannot find standover anywhere - yet everything else points toward a 54

Any input or suggestions welcome

Cheers

Forget standover height - it's just adding confusion to the picture, particularly when frame geometry can mean differences in the slope (or lack of it) for the top tube.

Much better to look at the stack and reach figures and compare them. On your current bike check out the stack and reach figures. I've found a link to the 2018 model which will give you an idea - just click on the geometry tab.

https://www.giant-bicycles.com/int/tcr-advanced-1-2018

The link below shows how to measure stack and reach yourself if you want to know it for the exact set-up you have with the stem and spacers on your current bike

https://rideonmagazine.com.au/how-to-measure-stack-and-reach/

You then need to find the closest match to those figure with the new bikes you are considering. You can then find the frame that is closest to what you want and you can the tweak the stem length and spacers to get it exactly right.

dimmock_g

Thanks both

I've compared lots of figures and forgetting standover height the reach and stack figures appear to sway in my favour for the bikes I'm considering - reaching being marginally less so not as low down and stack a tiny bit more so slightly more upright which is the adjustment I'm trying to achieve

dimmock_g

Current bike stack and reach....

545mm and 383mm

Potential bike stack and reach....

567 and 377 (in an M)
546 and 374 (in an S)

Current bike I've gone 10mm shorter on the stem (100 to 90), so the reach on the small is bang on

Currnent bike I've also put all spacers under the stem to raise it a few MM from the 545, so I think the S in the potential bike?

tangerineowl

20mm difference in stack height between S and M. If you were running 25mm of spacers for example under your current bike, you'd only need to run 5mm if getting the M.

Check the wheelbase on the M against S. If you think that extra length is too long for you, then get the S with a bunch of spacers below stem.