Either male into female of the normal bolt, or male into thread of the chainring (thinking 30mm NW’s here). Have had a quick Google but no obvious answer found.

2.6mm.

No more, no less? 🙂

Not sure on the specifics but I have just fitted a 30t NW chaining and initial tried the shorter chaining bolts that I had been using with a 32t NW chaining.

I wasn’t confident they had were deep enough so used some normal chaining bolts like you would have on a triple, I take it your having the same concerns?

Well at the moment I have a 32t on an XT M785 crank, with 2mm spacers and 8.5mm long bolts. I also moved the lone BB spacer from the DS to the NDS to get a good chainline.

I’ve got a 30t SS chainring coming to try out, which effectively has the spacer built in for chain/spider clearance, so I was wondering if I could put the BB spacer back to the DS to get the cranks properly centered again, and use the 2mm spacers with the 30t chainring to get the chainline right – if the 8.5mm bolts would be long enough.

If a standard 6.5mm bolt is ok with these threaded 30t rings then I would have thought an 8.5mm bolt would be ok with a 2mm spacer on? Unless there’s something I haven’t considered?

3 turns as with any other thread as a general rule

Yep, what he said ^^^^

Super, I shall try that – not heard that before.

The only thing to remember when spacing the 30t out is you might space it out so the little bits that protrude from the chainring (that take the place of the inner chainring bolt) no longer engage in the crankarm..

I spaced my 30t chainring in 3.2 mm and had to cut some inner bolts to the same thickness as the crankarm tabs.. then thread thEm onto the bolts to remove the play..

If that makes sense..!

I can see the bit of the chainring you mean, and hadn’t thought of that. I don’t quite follow your solution though?

EDIT – After a couple minutes more thinking I now see what you did.

I Cut the flange off the bolt on the right (that the chainring bolt tool engages into) so it was about same width as the crank arm tabs…

Then I just threaded it onto the chainring bolt on the left to the end to act as a spacer..

I’ll have to have a look when it arrives, but won’t the 2mm spacers I already have fit over the round sticky out bit on the chainring, and so prevent it engaging with the crank arm, and therefore keep it out by the 2mm I’m looking for? That would I suppose put all the stress on the bolt, not on the interface between the crank and chainring, which might be bad.

Yeah the spacers will fit over the sticky out bit..

But the sticky out bit needs to be in the hole in the crank arm so the ring can’t rotate back and forth slightly..

Because The bolt on the left doesn’t completely fill the hole in the crank arm..

If it where a normal chainring you would use longer versions of the bolt on the right to compensate.. but as that bolt is essentially now part of the chainring on the 30t the cut down bolt threaded on extends it for you and fills the space left in the crank arm tab..

I’m with you. That might be a bit fiddly without a vice. What do you think about it putting all the force through the male part of the bolt, if the sticky out bit isn’t engaged with the crank arm?

Itd work.. it was just the play under load that concerned me.. the threads would dig into the crank arm tabs too..

And yeah it Would be tricky without a vice..

I threaded the 2 together partly then just used the dremel to cut them in the vice..

I managed to get two out of each long female bolt I had..

I’ll have a look when it arrives – thanks very much for your top tips.