I have a M780 crankset, looking to convert it to a 1x11 with an oval 104BCD Absolute Black 30T chainring (which i already have).
The spacers that come with the chainring (the ones that provide the correct spacing for the smaller threaded don't fit in the bolt holes.... I'm guessing i've got the wrong bolts for this setup? Or have I screwed up completely and that chainring won't work at all with the M780 spider...?
Bump...
I can't directly help I'm afraid but would suggest posting a pic as this may jeep others vivre you an answer bud?
Good luck getting it sorted either way. 🙂
Assuming that the holes on the chainring match the bolt holes on the crank arm, then maybe all you need are the correct size chainring bolts
At the mo, the cheapest I've seen truvatIv single ring crank bolts is on amazon for £5-99 for a set of four...if that helps.
I used these [url= http://www.charliethebikemonger.com/id-cromo-chainring-bolts-128-p.asp ]link[/url]
Yeah, the [url=
"spacers"/washers[/url] on the 30T oval won't work on a triple spider, as there is no countersink to keep them from rotating.
Either you get someone to make you some that will fit the holes (and have an outer edge that sits on the spider), or you get a 32T oval ring.
[img] 
[/img]
That chainring looks a bit odd in terms of holes / bolts to go with it.
I've got an oval chainring which I've fitted to triple SLX cranks with no issues - but it's a 32t one so has normal looking holes with standard 104bcd spacing.
Looks like the easier solution is go up to 32t chainring - unless someone knows of a solution for the bolts. Presumably there must be one, unless the 30t isn't designed to work with that Shimano crank.
What cassette are you running? I've got an 11-42 on the back and the easy gear feels very easy - but when I bought it I checked that the ratio wouldn't be any different to the easiest gear I had one my previous 2x10 arrangement.
That's right for the AB 30T oval - the thin bolts and offset washers are to allow the narrow axis of the oval to fit and not foul the chain, the long axis of the oval uses normal bolts.
Cheers all. otsdr - that is the conclusion I've reached too. Managed a bodge yesterday (large washers that covered the holes and luckily the T25 torx screws were long enough) that let me get out for a ride.
Bit frustrated as the AbsoluteBlack websits says, "Compatability - All cranks with 4x 104BCD interface. That means Shimano XT....". Shame it only means newer versions.... unless they do indeed do spacers to suit this issue that I'm not aware of.
Verdict after using with the bodge - I loved the oval chainring. Felt weird for all of 5 minutes then just felt right. When climbing on loose(ish - too wet to be properly loose) climbs, there is much less wheel spin as the power transfer to the wheels is more even. Climbing very steep hills feels easier on the legs.
joebristol - I've got an 11-42t cassette. Was previously running a triple, so largest ratio with 30t is about 7% less than it previously was, so jumping to a 32t might be a step to far for the type of riding i do. Although, cost of new cranks (if i can't get washers to suit) might mean i just man up and go for 32t....
So, turns out i have the right set-up afterall. I emailed Stan at Absolute Black and he says that the spacers are meant to sit proud of the spider. Doesn't look great IMHO but then again, a triple spider running a single chainring doesn't look great anyway - can't polish a turd!