Rear wheel on the commuter making a "rat-a tat tat" kind of noise when free-wheeling, is it fubared or is it just the pawls sticking from winter gunk?
Ultegra road wheels if that makes any difference?
is it fubared or is it just the pawls sticking from winter gunk?
Probs both...you can try "servicing it" (you can get special tools, or some say a soak in gear oil works well, not tried tht as I can't find any for <£10!) but evidence on how well that lasts is sparse.
I'd just replace if it's a concern - 105 will probs fit.
one of the pawls might have snapped and you may have metal in there, or the seal might have let some dirt in
I've just replaced the pawls on my Hope hub (4 years old), 3 of the 4 had snapped and it was a bit of a mess inside, but all good now
I think the best thing to do is strip it down and see what is causing the noise, a visual evaluation combined with simply testing the functionality of the parts should do it.
Good luck!
Have you got one of those plastic spoke protectors behind your cassette, sometimes they can work loose and make a racket.