I've been looking at the BMC TM01 geometry, and I see the tt and reach length of the M-S is shorter than the S. What am I missing? I was thinking I would be the M-S or M-L, but the M-S looks so different in the numbers. Any thoughts? Thanks.

Have you tried TM01 sizing process

I wait even on a TM01 and though I am 180cm high so I need a size: small.

I entered my data from the single-start bike that I ride today. And it says size: S or M-S to me.

Look here and see all 32 options you have to set the stem in the right position.

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A Power2max user..

You are not missing anything. The MS is shorter than the S. The numbers on the geometry chart are correct.

I am 5'9" and ride a MS TM01. I previously rode a Cervelo P2 in a size 54, which has a stack/reach of around 51 and 42 cm. I rode it with a 90mm stem and a Visiontech basebar and extensions with 2.5mm spacers under the pads, so I was riding with a pretty standard stem and a very low aerobar setup. On paper, I should have been a near-perfect match for a ML, but the ML was too long for me and the MS ended up being the right fit. IMO/IME, bikes with bayonet style front ends can fit differently in reality than they may appear on paper. It is a great bike, with really good stiffness, handling, and ride as far as TT bikes go. Given its geometry and the way the TM01 fits and also its mechanical quirks, particularly with the cabling and brakes, it would help a lot to visit a shop with a lot of experience fitting and wrenching this bike. Also, if you get one, brake levers with barrel adjusters are a must.

- Ken

Thanks. I took a look at the fit calculator but I only have numbers for my road bike - not a comparable TT bike. I went to a local shop where they measured me up for a Cervelo P2 in 54. My thought was that the 54 looked like a near perfect match to the M-L, so I am confused by the numbers. The M-S looks small.

377 is a crazy short reach for a tri bike, particularly one with a 515 stack. BMC pretty much wanted to make a bike for the average person, they just opted to only do it in medium as opposed to all three sizes.

I would imagine the S, M-L and L as one method of fit and the M-S as a whole different method of bike fit.

I, like you, was sized on a 54cm P2, but ended up fitting on a MS TM01. It looked crazy short on paper, but it fits me just right. As I said, you need to go to a shop that knows the BMC TM01, knows how to fit it, and knows how to wrench it. You should probably even ride both a MS and ML if you can. Only then can you get the right size for you.

- Ken