I built up a QX RGB 27.5 a while back using QX hub and splined cranks, all brought new and my first time using splined connection.
I always had a small annoying creak which I couldn’t find until now.
I have found it to be around the crank to crank arms area. I have removed arms , cleaned and applied small amount of grease to the splines and refitted.
This has definitely helped and made it lots better but I do think it’s there still , I am going out tomorrow for a ride on it which I’m hoping will be creak free/better
Does anyone have any experience with this that could help cure this niggly creak ?