When I had the SD in for a valve check at Fowlers in Bristol a few weeks ago they said that the front wheel bearings needed replacing. Im booked in to have this done in a few weeks time along with some new tyres but I have another problem that I think might be related.

The last few weeks Ive been thinking Ive got an issue with my front discs or pads. Because I have cast iron discs they are a bit of a nightmare when they rust up but usually a few miles and the roughness wears off and they work perfect. But lately I started to feel a judder when I apply the brakes - it feels like there is a roughness as though the rotors had lumps on them. The brakes work fine and are still awesomely powerful but the roughness is most apparent when the lever is only a bit applied and then it's not as noticeable when the brakes are applied hard.

I thought it may be the rotors developing a warp or something. But when I had the bike up on the stand today I strapped the back end down on the Abba stand so the front was up in the air to try and see what the bearing issue was. I couldn't feel any play but when I spun the wheel I could hear a definite grumbling, rough sound. I guess this is what the mechanics at Fowlers must have also noticed.

So my question is there anyone on the forum who's had knackered front wheel bearings who can confirm that this is also the cause of my front front brake feel issue? It seems to make sense to me that this could be the case but I've never, in the whole of 35 years of bike ownership ever had a wheel bearing fail so have no experience of this.

Your thought would be appreciated. It would save me worrying about other possible causes and be happy to wait until I get new bearings and see if this clears up the problem.

Never experienced it personally, but it makes sense that it could be the bearing as it affects the relationship between the wheel mounted disc and fork mounted caliper.

Have no experience of cast iron discs but have replaced front wheel bearings on my SDR two or three times and, yes, brake feeling could be symptom of failing bearings - don't wait a few weeks to replace as I've had failing bearings collapse very quickly after initial diagnosis - not good at 80-90mph.

When I got mine MOT'd last month I got an advisory on worn front wheel bearings - as you mentioned a slight grumbling. I took the pads out and the noise/resistance was still happening when I spun the wheel, so not the brakes.
I haven't noticed any juddering when braking though. Sorry - not much help really!