I was out riding today and my nimbus 29er has started what seems like the disc is catching the calliper on each revolution when under load going up hills.
I checked the tightness of all bolts and everything is tight but no change. Either I’ve developed stronger legs that are twisting the frame or something else is up.
Anyone experience this?
Sounds like the caliper is not centred to the disc , if you look into the pads with light behind the caliper you will probably see a gap between pads and disc on one side but not the other.
To centre you can loosen the caliper bolts which allow side to side movement and whilst holding holding brake squeezed re tighten the bolts and see if you have gaps , or you can loosen the same bolts and move caliper around to get egual gaps between disc and pads on both sides to prevent rubbing.
The Disc could have been too hot and bent so much that the dics rubs against the pads so that the impleller can no longer turn freely, as was the case wirh me. You can also simply bend rhe disc a liittle in the direction you want wirh your hand, but be careful.
If you have not, be sure to check your bearing cap bolts. There is a very fine line between too tight and too loose and if too loose it can cause your issue when under heavy load. Another option with the bearing cap bolts is to add very carefully selected spacer washers so the bolts can be tightened fully without deforming the bearings.
First I would of course check the screws on the bearing shells, but you already have that. It is not uncommon for the brake caliper to have to be realigned. What I would also check if I had the opportunity is whether the screws on the disc are tightened well. They can also become loose. You will probably have to dismantle the cranks and ball bearings to do this. But you can at least remove the wheel and see if you can move the brake disc by hand.