Mirror change - broken bolt

I thought I would move the black Rizoma mirrors from my silver 961 CR to the new black SP that arrived a week ago. The left hand mirror was fine but when I tried to remove the right hand mirror from the SP all I succeeded in doing was to break the bolt holding it to the brake assembly. It's a 6mm bolt and I guess the torque setting shouldn't be that much and I'm wondering if they managed to bottom out the bolt. The RH mirror fitting looks different to the LH fitting and appears to have a locking nut. It doesn't have a lock nut, it's a single unit with one nut designed to look like two nuts?

What are the chances of removing the broken bit of bolt without messing up the fitting?

comet said:

I thought I would move the black Rizoma mirrors from my silver 961 CR to the new black SP that arrived a week ago. The left hand mirror was fine but when I tried to remove the right hand mirror from the SP all I succeeded in doing was to break the bolt holding it to the brake assembly. It's a 6mm bolt and I guess the torque setting shouldn't be that much and I'm wondering if they managed to bottom out the bolt. The RH mirror fitting looks different to the LH fitting and appears to have a locking nut. It doesn't have a lock nut, it's a single unit with one nut designed to look like two nuts?

What are the chances of removing the broken bit of bolt without messing up the fitting?

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You do know that the RH mirror is a LH thread (or should be)?

And it’s M8.

Do you have access to a pillar drill? That will be straightforward enough to remove, drill and then get a stud extractor to into it, you will need a LH thread extractor of course.

You can buy that piece, proper Brembo ones are £50 ish. Cheapo repro much less.

Fast Eddie said:

You do know that the RH mirror is a LH thread (or should be)?

And it’s M8.

Do you have access to a pillar drill? That will be straightforward enough to remove, drill and then get a stud extractor to into it, you will need a LH thread extractor of course.

You can buy that piece, proper Brembo ones are £50 ish. Cheapo repro much less.

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I was just about to post that - felt pretty stupid when I realised.

I must have known that before as I fitted the Rizoma mirrors to the CR, memory is failing, amongst other things.

And you're right, it's an 8mm bolt.

The broken bolt is out now, just took some gentle tapping with a centre punch.

I feel partially vindicated, as the eqivalent thread on my 2013 CR is definitely a right hand thread, with a 10mm bolt.

The RH mirror is supposed to be a LH thread so that it will loosen (and therefore yield) in an impact.

Fast Eddie said:

The RH mirror is supposed to be a LH thread so that it will loosen (and therefore yield) in an impact.

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Not sure why they would be fussed about a mirror giving way in an accident, I figured it was more to do with it not coming loose while riding with wind resistance/vibration, like the left hand pedal on a cycle. Anyway, the original Brembo right hand fitment on my 2013 CR definitely has a right hand thread.


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comet said:

Not sure why they would be fussed about a mirror giving way in an accident, I figured it was more to do with it not coming loose while riding with wind resistance/vibration, like the left hand pedal on a cycle. Anyway, the original Brembo right hand fitment on my 2013 CR definitely has a right hand thread.

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If you think about it, when the LH bar has a RH thread, and the RH bar has a LH thread, wind pressure will actually LOOSEN the mirrors.

The reason is so they yield in the event of impact.

How sensible this may or may not be is another matter entirely…

Fast Eddie said:

If you think about it, when the LH bar has a RH thread, and the RH bar has a LH thread, wind pressure will actually LOOSEN the mirrors.

The reason is so they yield in the event of impact.

How sensible this may or may not be is another matter entirely…

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You're right, I hadn't really thought about it. I now just need to remember that I've got a 961 CR with a RH thread and a 961 SP with a LH thread.

I think the Rizoma mirrors look ok on the black bike.