Most likely Medium as most have said, but there could be more to it than just your height.
And as was also said, one brand's medium is another's small or large.
Once you know your size based on geometry then it becomes a little easier.
In addition to what's already been said ...
Does it happen on all gear combos.?
Is it possible that it's in a gear where the FD is contacting the chain enough to cause it to want to climb.?
Unfortunately some shops will try and sell whatever they have available whether suitable or not.!
That said, brand/model/geometry can also mean different sizes.
Oversight on my part ... I forgot the required 10 sec incorrect install of battery. (thought of it while browsing for a replacement)
Crisis seemingly averted ... 🙈
PS Garmin Dual R999.
Xoss X2 R699.
So it seems my Garmin transmitter(1st gen) has died without warning. The strap was already replaced.
Thought it was just the battery but a new battery hasn't helped. ☹
I suppose they all need replacing at some point ...
My experience with Cyclelab Online (albeit limited) has generally been good.
It's this polka dot/last stock sale that has then chasing their own tails.
Polka dot chaos.? Hope you get your goods and worry less about how long it takes ...
And forget about reaching out to them because that appears to be even more chaotic. 🙈
Looks like the Garmin Edge 705 from back then.
That Garmin had more than enough features for the average user.
Hopefully the Bryton is similar.
20 years old would raise concerns about battery life though.
I was able to change the battery on my 705 and was still using it not so long ago.
Only changed in order to have something that was radar compatible.
