sizing advice 54 or 56?

tonyhogg

I've currently got a Colnago C60 in a 52s size frame, fits me superb, 1 small spacer below the headset, although its closer to a 56cm effective top tube its still more like a 55/54cm size.

How does a BMC SLR01 http://www.bmc-racing.com/int-en/bikes/ ... ammachin... size 54cm or 56cm compare to the Colnago in a 52s (sloping) http://colnago.com/geometry-c60-2-2/?lang=am I really struggle to make sense of the various geometry charts, I know the stem length and bars width of the BMC in a 56cm does not suit me, briefly tried a 54cm size and it felt ok.

inseam 84cm
trunk 61cm
forearm 34.5cm
arm 68cm
thigh 60.5cm
lower leg 56cm
sternal notch 144cm
total height 178cm

Any advice regarding sizing would be appreciated because I'm struggling to choose between the BMC in a 54 or 56, edging towards the 54.

dj58

The horizontal TT length on the 54cm BMC is 550mm, the same as your 52cm C60, so if you tried the 54cm BMC and felt ok then go with that. Although the HT height on the 54cm BMC is 148mm, wereas the 52cm C60 is 163mm, however you can adjust the difference with spacers if necessary.

Grill

54. If in doubt go small, although looking at the geo there shouldn't be any doubt.

tonyhogg

It's really confusing, I seem to have had two bikes recently Scott CR1 in medium 54cm and now this Colnago c60 in a 52s (sloping) that aren't really comparable to any other brands sizes and give me anything to go off. I would have thought the BMC in a 54cm size but lots of spacers under the stem and a big saddle to bar drop isn't such a good look.

letap73

tonyhogg wrote:

It's really confusing, I seem to have had two bikes recently Scott CR1 in medium 54cm and now this Colnago c60 in a 52s (sloping) that aren't really comparable to any other brands sizes and give me anything to go off. I would have thought the BMC in a 54cm size but lots of spacers under the stem and a big saddle to bar drop isn't such a good look.

In terms of stack and reach the 54 is closer, however it appears to have a longer reach/shorter stack in comparison to the C60 - so you are looking at a more aggressive fit. There is nothing wrong with a large drop -if you have the flexibility to cope with it. Neither is there anything wrong with having a number of spacers under the stem if it helps you to achieve the correct fit.

Out of interest, why are you looking at a new bike so soon after buying the C60?

kajjal

letap73 wrote:

tonyhogg wrote:

It's really confusing, I seem to have had two bikes recently Scott CR1 in medium 54cm and now this Colnago c60 in a 52s (sloping) that aren't really comparable to any other brands sizes and give me anything to go off. I would have thought the BMC in a 54cm size but lots of spacers under the stem and a big saddle to bar drop isn't such a good look.

In terms of stack and reach the 54 is closer, however it appears to have a longer reach/shorter stack in comparison to the C60 - so you are looking at a more aggressive fit. There is nothing wrong with a large drop -if you have the flexibility to cope with it. Neither is there anything wrong with having a number of spacers under the stem if it helps you to achieve the correct fit.

Out of interest, why are you looking at a new bike so soon after buying the C60?

This is good advice, think about the riding position you are after. A small bike can be adjusted but if you want very little drop the next frame size up may suit you better as long as it is not too big. My wife chose a bigger frame as she prefers little bar to saddle drop.

Grill

Bar to saddle drop is the same on either size frame if you transfer geo. Difference is between how many spacers and how much seat post is showing.