Rumbly noise in back wheel

apple eater

Trek xcalibur 7 29er ( i think it's a shimano hub)

This noise is a noticeable rumble/mild grind type of noise and i think is coming from the hub. There is no play in the wheel.

When it first happened it just came on after about 15 miles of road riding, this was about 2 miles from home. It was only just a noticeable noise.

When i took the axle out one side had ample grease the other (derailieur side) had less and was blackened, the grease i use is red. Possible chain oil contamination?

So i cleaned out that side and regreased with sufficient amount of grease.

The next ride it came on again about 15 - 16 miles into a road ride home from work. This time the noise, although the same sound, was a little bit more audible.

I haven't stripped it again yet but i am wondering if somehow the grease has become contaminated and this has resulted in one side of the hub wearing out?

Any other idea's?

The Rookie

If the bearings or races are shot then fresh grease won't fix it, the blackening could be anything including metal particles coming off due to wear, did you inspect the balls and races when it was apart!

dgunthor

spin the loose wheel in your hands holding the axle either side - you'll feel the rough axle bearings if that's the issue.

if it is rough, clean out, replace the loose bearings and use fresh grease. should help smooth it out.
look at the old ball bearings you may see they are not shiny / have corrosion / etc

Barnymeinhoff

could be worth looking for a loose spoke as well.

apple eater

Update on this, new axle and bearings fitted and i still have the rumble.

Spoke tension is fine and no buckles.

However the noise is only there on free spin, it disappears when pedalling.

The cassestte has a slight wobble but is tight on the hub. What can cause this, i'm not sure what is underneath the cassette in terms of exposed parts?

The Rookie

Freehub bearings then, I wish you'd said the bit about freewheeling earlier!