Confused with bike sizing


Great Yarmouth
Hi, Can you help me out with bike sizing, I'm 5' 8" – 171cm, inseam 32” - 81cm I've been told I need a medium size fram , most medium size frams are 21” - 54cm, on canyon’s built in sizing tool on their web site I put in my height and inseam measurements and it told me I'm a XS 18.5 47cm can you advise thanks


Different frame makers measure different. Canyon I believe measure from the centre of the crank to the top of the seatpost while others measure the top tube(theoretically). The XS small will no doubt have a 54/55cm top tube and those bikes measured as a 54cm top tube will have a 47-51cm seat tube.

All uphill

I didn't recognise you but I knew your bike
I'm a similar size to you and 54cm bikes generally work for me, however I would never buy a bike I hadn't sat on. Maybe that's just me, but it has to feel right and look right and that can't always be confirmed from an image on a phone or laptop.


It'll be Reyt.
Which Canyon are you looking at?
I'm 5'6" with a 30" inside leg and my Ultimate SL CF was a Small.I could also ride my mate's Medium.Unless canyon have changed their measuring system then I's say XS is way too small.
I compared the Geometry of the Ultimate with the bike I had and Small was closest.


I use the notional horizontal top tube measurement for comparing different bikes. I'm about the same size as Sniper and normally ride 'Small' frames. I also come out as XS on Canyon, which I think is probably about right as the tt measurement is 529mm. I'm normally looking for a tt round the 530 mark.

I think I'd rather have a frame that's slightly small as it only takes a longer stem to get the fit right.


Über Member
If you can, find a good local bike shop that will do a bike fit as part of the purchase.
I'm 5'6" and 29 inch leg. I had an excellent bike fit at my local shop to determine which frame size I needed.
So my Trek Domane SL5 is a 52cm frame. I could ride a 54cm frame easily but the reach to the handlebars was uncomfortable.
I'm now changing the handlebars as Trek decided that people with short legs don't have broad shoulders, so I need wider handlebars than come fitted.

There are quite a few different dimensions to take into account and only by being fitted and trying the bike can you be sure it is right for you.


Wheely World
Most manufacturers have a size chart to help or local bike shops will assist with sizing. For the size charts if you are roughly in the middle you will be fine only if you are between sizes it becomes harder to choose. In general a bike that is a little too small can be made to fit easily enough but a bike that is too large cannot. In my case I am tall with a proportionally longer body which means I often need a size lower than the size charts suggest.
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