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I bought two Superstar oval* chainring and didn't realise until they arrived that they are intended to go on the inner position.
This isn't too much of a problem as I can swap the spacers round on my singlespeed and still use them.
I need one for my Rohloff though, and with the 13t rear sprocket, the front ring needs to be in the outer position to get the correct chain line.
All the ones I've looked at look like they are for the inner position. The markings are worn off the one I'm replacing so I can't just order the same again.
The axes of the ellipse are only slightly off the midpoint of the mounting bolts. I probably wouldn't notice the few degrees of error, but the teeth seem to be an odd profile and I don't know what would happen if I ran it backwards.
Who makes an oval chainring for the outer position?
Do all narrow/wide chainrings use an odd tooth profile or can some be run backwards?
Why do none of the adverts or product descriptions state whether it's for the inner or outer position?
*Yes, I know they are elliptical really.
being as narrow wide is or 1x drivetrains, there is no outer position technically, just one position
So the question is, what crank have you got that you are trying to to fit a chainring to?
i think 104 bcd fits standard shimano cranks
Shimano XTR triple on the Rohloff and Race Face triple on the single speed. Both 104mm BCD and both with the ring currently in the outer position.
Also available in a 34t
Thanks, but I'm not convinced.
The picture shows it mounted on the inner position.
The tooth profile looks normal, so I could just mount it backwards in the outer position, except...
The major axis is horizontal when the crank at at 116 degrees. Mounting it backwards would put it at 64 degrees if I've understood that right.
Thinking about it now, no one offers a choice of inner or outer for narrow/wide oval chainrings. I'm guessing that's because everyone uses them in the inner position, so there's no need to describe them as such.
Which means I've probably been using mine backwards with the major axis at the wrong angles for years without realising.
The Rohloff sprocket is my one fixed point. I'll have to see what I can do with swapping single speed spacers and bottom bracket spacers, and sliding the EBB across in the frame if I have to to get them both lined up properly.
Not sure what cranks and spider you're running, but you should have a gander at absolute black. Lots of different permutations. Have just put some sub compacts (46/30) on my ultegra cranks and it is flawless.
Not sure what cranks and spider you’re running...
despite me posting 2 hours earlier
Shimano XTR triple on the Rohloff and Race Face triple on the single speed. Both 104mm BCD...
Again, no mention of whether it's for the inner or outer position, but 50mm chainline sounds like the middle of a triple chainset. What makes you think it would fit the outer?
I bought two Superstar oval* chainring and didn’t realise until they arrived that they are intended to go on the inner position.
You sure? Where did you get that from? I've got a Superstar oval 110bcd running happily on the outer ring side of a road compact to emulate the chainline of a GRX. Superstar are 0mm offset as far as I remember.
Why can't you just screw it onto the other side of the crank spider?
despite me posting 2 hours earlier
You're expecting me to do the hard yards?
Just suggesting you take a look 🤔
Rotor rings have multiple holes for different timing, so you should be able to reverse one and line it up right -- although they only do weird bcd from what I remember
Also, daft question potentially, but is there any reason you can't just put the Superstar ring the normal way around on the outer position? The chainring bolts would surely be fine with some spacers behind them so they don't sit directly on the cranks
(also I agree with you on the tooth profile -- the superstar is strange and I'd not want to run one backwards)
You sure? Where did you get that from?
That's the problem, no one actually says they are for the inner position, but if you look at my photo above, you can see the writing is on the side with the plain holes. The side with the counterbores for the bolt heads has got no writing.
Assuming it's designed so that the writing is easily visible in use, that means it mounts behind the spider.
Why can’t you just screw it onto the other side of the crank spider?
You can, and it looks like that's what I did on my single speed because I didn't know any better at the time and I've got away with it so far.
It's not ideal though. Reading through product descriptions, it looks like they are designed so that the major axis of the ellipse is vertical when the crank is about 10 to 20 degrees past horizontal.
Mounting it backwards means the major axis of the ellipse is vertical when the crank is about 10 to 20 degrees before horizontal.
It works, and who knows, it may still be better than a round ring, but it's not how they are designed to work.
I just had a look at Rotor and they don't list 104mm BCD. https://rotorbike.com/chainrings.html
Why can’t you just screw it onto the other side of the crank spider?
You can, and it looks like that’s what I did on my single speed because I didn’t know any better at the time and I’ve got away with it so far.
It’s not ideal though. Reading through product descriptions, it looks like they are designed so that the major axis of the ellipse is horizontal when the crank is about 10 to 20 degrees past horizontal.
Mounting it backwards means the major axis of the ellipse is horizontal when the crank is about 10 to 20 degrees before horizontal.
It works, and who knows, it may still be better than a round ring, but it’s not how they are designed to work.
I assume ceept meant what I did -- why not simply screw it into the outer position without flipping it, so it has the same alignment?
Ah, I see what you mean now.
Yes, that would work, although aren't the bolt heads recessed into the ring to give extra support?
I've always assumed the bolt head acted like a larger dowel to take some of the load off the smaller threaded part of the bolt, but now that I think about it, there's no corresponding counterbore in the spider.
On the other hand, the bolts are in single shear, so having a counterbore on one of the mating faces weakens the interface.
I'll give it a go on the Rohloff first. There's always the option to change down a gear, so I tend to sit and spin rather than lunge to a standstill like I do on the single speed. What's the worst that could happen?
That’s the problem, no one actually says they are for the inner position, but if you look at my photo above, you can see the writing is on the side with the plain holes. The side with the counterbores for the bolt heads has got no writing.
Assuming it’s designed so that the writing is easily visible in use, that means it mounts behind the spider.
OK, you've got me looking now. As per above mine is 5 bolt 110bcd so obviously road. But I've definitely got it mounted correctly on the outer position. Print facing out and the counterbores are on the outside too, so all good.
mine is like this:-
But your photo above....yours is kind of weird. The teeth design is nothing like mine. And as you say it does look like its meant to be mount on the inner
But then again - this is the photo of the 104bcd raptor narrow wide from the Superstar website and that is nothing like yours. Which one is yours?
That's the 32t version. If you look at the list under Tech Specs it says integrated nuts for the 32t.
It doesn't really show on the photo, but I think those are tapped holes or 'integrated nuts' as they call them. I guess they are made deeper to give more thread engagement into the aluminium.
https://www.superstarcomponents.com/en/raptor-oval-chainring-104bcd-narrow-wide.htm
Edit;
There's a video here explaining the stand offs and tapped holes.