Rear Brake issue 2018 GS

[phillh]

Hi all, any advice would be appreciated.

Back in March, I checked bike over for MOT and all was ok.

A couple of days later, I jumped on it to take it to MOT test and rear brake pedal sank to floor with no rear brake effect.

I took my other bike for test instead (which surprised inspector as he was expecting a 2018 GS not a 2008 MT01) and adjusted
the rear brake using 10mm and 12 mm spanners till it worked.

Checked bike, all fine, took for MOT which it passed a week later.

Have used GS several times since and it has been fine.

Took it out Wednesday evening to go to a bike show at Meldreth.

Had ridden about 2 miles when rear locked up solid.

Managed to get to a safe spot and found rear brake pedal locked solid.

With assistance from my other half and a 10mm and 12 mm spanners, freed off the rear brake and all is fine now. Rode onto
the bike show and back with no problems.

Any useful thoughts please?

 

[Victor c]

If you have adjusted the foot brake pedal, that is why it has locked up. It requires a couple of mil clearance to allow for heat expansion.
There is a known issue with the rear brake taking in air, so it will need bleeding. I had to do this a number of times on my previous bikes, but my current 2021 GSA does not appear to suffer with it.

 

[GrinningGSer]

There was an incident recently ‘Travels on my motorbike’ , when Fraser was suffering a red hot rear disk ; which needed water pouring on it .

Close inspection by BMW , revealed a small stone , or something , jammed somewhere near the brake pedal , mystery cylinder.