Another chainring question - 30T, non offset

[AlasdairMc]

I need a 30T chainring for a 104BCD crank, but it must be straight and not offset or with threaded bolts.

I’m having some issues with spacing on a new purchase so need a very precise fit, and it seems that most 30T chainrings have threaded bolts and push the ring in by about 4mm.

What’s out there that looks just like a smaller version of a normal chainring?

[Bearbonesnorm]

Can a 30t 104mm ring actually be made without captive nuts?

[AlasdairMc]

Can a 30t 104mm ring actually be made without captive nuts?

I really hope so! I’ll try with some axle spacers if this doesn’t work, or resort to an entirely different B.B. strategy. I’ve got 6mm on the axle now, will see how much more the axle will take while letting the splines engage properly.

[Dr Nick]

I've recently fitted a Renthal 30t ring on my alfine equipped genesis and the spacing was the same as the previous 32t ring despite the 30t having threads... (I'd planned to try an oval ring but couldn't due to it changing the chainline...)

[fatbikephil]

You need the wee threaded bosses to enable the chain to clear the crank spider. You could try to lash something up - grind off the ends off the spider and machine off the chainring threaded bosses but it will be very tight....

[Justchris]

You may not get that. The 4mm spacing is to push the spider arms away from the teeth and let the chain engage with the teeth.

[Alpinum]

You may not get that. The 4mm spacing is to push the spider arms away from the teeth and let the chain engage with the teeth.

This

[AlasdairMc]

You may not get that. The 4mm spacing is to push the spider arms away from the teeth and let the chain engage with the teeth.

Damn. Hopefully the axle spacers will fix it then, otherwise it’s a 32T and pushing.

[Pete-G]

Bigger cassette or one of the expander gears then?

[Bearbonesnorm]

If you're stuck with 32t, how about going oval?

[sean_iow]

I've got an oval 32 and it's got the little threaded stand-offs as I think it's the same problem as a round 30. It's only as wide as a 30 in one direction and as wide as a 34 the other way across. Without the little spacers the chain would hit the crank tabs at the narrowest part.

[wriggles]

30t has to be offset to clear the 104 bcd spider.

Alternatives; 5 arm 94 bcd crank or direct mount cranks will take a non offset 30t ring.