MTB to Road Bike - Understanding Sizing

uggers

I'm looking at getting a Road bike to complement my mountain biking.

Currently I have a Large Stumpjumper 2021 29er

The size was advised by the shop I purchased it from. It was ok at first but i ended up having a bike fit to adjust a few things (slightly longer stem and get the saddle height/position dialled in) which helped alot.

I am now looking at getting a Canyon CF 7.0

The fitter who fit me says that I need to get a Large - which according to Canyon are advising a Medium.

My height is close to 180cm and 82cm inside seam

While that might be correct to go for medium on only that, as mentioned the fitter is recommending a large. Not that I don't agree with him I am just not sure what differences that would make coming from the MTB. I realise my position will change more (more lent over going from a MTB to Road) but I'm wary about purchasing a bike too large.

I've tried to look at the Geometry comparison on 99spokes.com / geometrygeeks.bike but I'm not all that great in translating it.

Fitter provided these measurements;


I do realise the main advise I'll get here is

1. I should discuss further with the fitter
2. Get a bike that I can test ride.

Which I will do for 1. although 2. is tricky with Canyon as a supplier and Covid availability for Bikes

But I did want to hear some other thoughts if anyone's had any similar experiences with MTB to Road or Larger bike than the norm.

webboo

If the fitter is advising that your bars should the same height as your saddle as in the drawing. You need to get a new fitter.

singleton

Have you sat on, or ridden any road bikes recently?
Can your fitter given you figures for your ideal stack and reach?

The best way to compare road bikes of different sizes, and even from different manufacturers, is to use stack and reach figures, but that really only helps if you have a reference point to start from.
More reading here: https://www.bikeradar.com/features/your-top-tube-length-is-irrelevant/

N0bodyOfTheGoat

webboo said:

If the fitter is advising that your bars should the same height as your saddle as in the drawing. You need to get a new fitter.

Unless OP has bad lower back history, which was why I originally chose the "58cm" Cube Attain GTC instead of the "56cm" at similar size to OP, although now I can usually run the stem on top of the conical spacer on the older alloy steerer.

Quotes around size numbers as no measurement matches the stated frame size, Cubes have very odd geo numbers that size much smaller than my previous Specialized and Felt.

By comparison, my Marasa hybrid and Wazoo fatbikes are both 18" frames.

photonic69

I’m 182.5cm and a similar inseam. All my road bikes have been 56cm or a M/L in Giant sizing and they fit me perfectly. I tried a friend’s 58cm Cannondale and it felt way too big to me. A big bike will always be big. A slightly smaller bike can be extended to fit better. Some Pro’s might choose a slightly smaller frame but have unusually long stems.
Is the bike fitter also selling bikes? I’d get a 2nd opinion from a different source.

uggers

thanks all for the replies

Managed to finally catch up with the fitter, and we talked it through and realized we had we'd made a miss-measure so now I'm sized as expected on medium

Partly my fault when we did a phone call and partly when we did the fit on the day. Mistakes happen but glad I had the opportunity to resolve it before purchasing.

It probably wouldn't of been do dramatic had Covid lack of supply means making quick decisions or losing out

singleton

I hope it fits perfectly and you enjoy your new ride.

savadeck

I am 177 cm tall and I chose SAVA R8020 hydraulic disc road bike. According to my height, I must choose the right road bike. I sell it in the online store, and they provide detailed configuration tables and size recommendations.
47cm is suitable for 158-165cm, 5'2"-5'4"
51cm is suitable for 166-175cm, 5'5"-5'7"4
54cm is suitable for 176-185cm, 5'8"-6'
56cm 186cm-190cm. 6'1"-6'2"
The current size is quite satisfactory and it is very comfortable to ride