Trek sizing

bikeit65

I have always rode a 54cm or M road bike, was in local bike shop today looking at a Trek Domane Sl6 and the shop guy was trying to push a 56cm onto me, he kept saying a 54 was the wrong size for me I'm 5ft 10ins, can anyone advise please?

imposter2.0

Your height is only one component of your size in terms of which size might be the best for you. Arm length, leg length, torso length, etc - all of these matter in determining a decent fit.

The guy might be right - or he might be wrong. It's impossible to say on the information you've provided here...

N0bodyOfTheGoat

https://www.trekbikes.com/gb/en_GB/bikes/road-bikes/performance-road-bikes/domane/domane-sl/domane-sl-6/p/28313/ "3 question size finder" put me on the 56cm, like OP I'm 5'10" and have stumpy ~32" cycling inseam for my height.

56cm has 377mm reach (11mm less than my "58cm" Cube Attain GTC) and 591mm stack (19mm less than my Cube). It comes with a 100mm stem, 10mm less than Cube, so bike is by default going to feel more upright.

bianchi_dave

Not the same bike (obvs), but I ride a 54 medium Trek Emonda SL6 (H2 fit, 2019) and its perfect size for me. A 56cm would be miles too big for me in most brands I think.

For reference I'm about 5ft 10in so similar height. It'll depend on how you're made as well. I have proportionally shorter legs and longer torso. I also ride two Scotts, a 52S Foil and a 54M Addict RC. I only need a 10cm longer stem (120mm) on the Foil, as although the effective top tube is quite a bit shorter than the Addict, the reach is actually less of a difference due to the different frame tube angles.

Another thing to consider is how much saddle to bar drop you have, as this may also dictate your frame size. A bigger frame would have a taller head tube, meaning you might not be able to get the bars as low as you'd like. Similarly one that has too low a head tube could mean a huge stack of spacers under the stem.

I'd like to know what the shop guy is basing this on, as there are a few variables. The last thing you want to do is buy a bike that's too big, whereas its quite easy to make a smaller one fit you properly. Being cynical it sounds like he's maybe just trying to sell the bike he has in stock.

A good idea is to take the stack and reach measurements from frames you know fit. This is a great tool for comparing, as it not only gives raw numbers, but also the differences between sizes (and brands) -
https://geometrygeeks.bike/

Hope this helps

bikeit65

N0bodyOfTheGoat said:

https://www.trekbikes.com/gb/en_GB/bikes/road-bikes/performance-road-bikes/domane/domane-sl/domane-sl-6/p/28313/ "3 question size finder" put me on the 56cm, like OP I'm 5'10" and have stumpy ~32" cycling inseam for my height.

56cm has 377mm reach (11mm less than my "58cm" Cube Attain GTC) and 591mm stack (19mm less than my Cube). It comes with a 100mm stem, 10mm less than Cube, so bike is by default going to feel more upright.

Done the 3 question size finder, it put me on a 54cm