Disc brake rotor rubbing on chainstay.

fattsmellf

I'm getting a second wheelset for my Norco Search Carbon for road/summer use, the bike has thru-axles (15mm front, 142x12 rear) and the stock wheels came with centerlock disc-brakes and fit fine. I bought a set of Fulcrum Racing Quattro Carbon wheels, I could only get hold of the 6-bolt version. The wheels fit in the frame - except that the rear disc rotor rubs on the inside on the chain stay and as you tighten the axle the disc is bent by the frame. It seems that the Fulcrum wheel places the rotor ~2mm further out than the stock wheel and the tolerances are so tight that this just doesn't fit.There doesn't seem to be any way to move the rotor closer to the wheel so I guess I have no option but to send the wheels back.

My questions are:
1) Do 6-bolt rotors stick out further from the wheel than centerlock rotors?
2) Do you think the centerlock version of the Fulcrums would fit, or do I have to accept that these hubs won't fit my bike?
3) Could I have known this beforehand? Is there any way I can see how wide a particular hub is apart from buying them and trying them out?

Thanks!
Matt

EDIT: By the way - the rotors were the same size as on the stock wheels (160mm), Shimano RT76. Cassette was the same as well (105 5800 11-32).

dork_knight

Have you tried to loosen and reposition the calliper to accommodate the new wheels (the rotor might be bending against the calliper and pushing it towards the stay)?

fattsmellf

Hi, thanks for the reply. Yes - I completely loosened the calipers, but the rotor is positioned so far to the outside of the wheel that it badly rubs on the inside of the chainstay no matter the positioning of the calipers. In fact I see now that I've slightly damaged the frame on the inside of the chainstay with the rotor :x ...

frisbee

The brake rotors should be in exactly the same position with centerlock and 6 bolt. I don't know if you'll be able to offset the calliper that far.

Have you fitted the end caps to the axle correctly i.e are the left and right ones different, assuming it has removable end caps for different axle types? Have you fitted the brake disk the right way around?

fattsmellf

I had the rotors/cassette fitted by my local bike shop, unfortunately they've already removed them again so I can send the wheels back, so I can't check that they were installed correctly, but I have to assume they fit them the right way round. The wheels already came set-up for 12x142mm so there were no end-caps required.

Yeah - I thought the centerlock and 6-bolt should put the rotor in the same place, so assuming they were fit correctly that must mean the hub on the Fulcrums is wider than the hub on the stock wheels right? So then the AFS/Centerlock version is also unlikely to fit I guess?

The Rookie

frisbee wrote:

The brake rotors should be in exactly the same position with centerlock and 6 bolt. I don't know if you'll be able to offset the calliper that far.

Says who?

Different hubs have the disc in slightly different locations, I had a similar issue with a (6 bolt) Novatec hub and a (also 6 bolt) Shimano Deore hub. In my case the disc was a hard foul on the calliper mount and even if it wasn't the stock M6 bolt and washer was so close the washer fouled the disc as well.

Some frame manufacturers just run it closer for some (stupid) reason so some hubs wont fit. This was the 4th frame the Novatec hub went on and the only one to cause an issue.

frisbee

The Rookie wrote:

frisbee wrote:

The brake rotors should be in exactly the same position with centerlock and 6 bolt. I don't know if you'll be able to offset the calliper that far.

Says who?

Different hubs have the disc in slightly different locations, I had a similar issue with a (6 bolt) Novatec hub and a (also 6 bolt) Shimano Deore hub. In my case the disc was a hard foul on the calliper mount and even if it wasn't the stock M6 bolt and washer was so close the washer fouled the disc as well.

Some frame manufacturers just run it closer for some (stupid) reason so some hubs wont fit. This was the 4th frame the Novatec hub went on and the only one to cause an issue.

Says the engineering world since the early 19th century...

Bicycle components that are intended to be interchangeable, such as wheels, need to conform to standards, such as the location of the disk.

The Rookie

They don't have to conform to a standard, no, they conform to a convention, but different hubs from different makers do put the disc in different places, that's why you had shims and now slotted PM mounts, if there was a standard you wouldn't need either.

frisbee

The Rookie wrote:

They don't have to conform to a standard, no, they conform to a convention, but different hubs from different makers do put the disc in different places, that's why you had shims and now slotted PM mounts, if there was a standard you wouldn't need either.

There are standards for a variety of cycling parts, the obvious ones are helmets and lights.

Just because there is a standard doesn't mean you don't have to shim or adjust things.

coops1967

I can only imagine you have hubs made for 135mm rear axles (?), is it very loose - are they any spacers for both sides of the hub/axle you've missed (to convert to a 142mm)?

Just changed wheels myself - Stans wheels stock hubs (with spacers) to DCR wheels with Tune hubs (which have no spacers as they are made to 142mm), and no major issues. ( I did loosen the calipers & apply brakes firmly while retightening the calipers to ensure they're nicely centred - but certainly they shouldn't come anywhere near your chainstay.)

The Rookie

The point is, that like it or not, different rear hubs put the rear disc and cassette in slightly different locations, you can argue about standards all you like, but compare a number of parts and it's fact, in the case of my two hubs the difference is at least 4mm if not more, in terms of the cassette location, the gears were precisely one gear gap out as well.

You'll be able to show me a standard?