So I've got a regular SRAM PG990 cassette, and looking to go 1×9 with my middleburn cranks…hence, looking to buy a MB Uno chainring. They come in 1/8 and 3/32 sizes. I guess it's all to do with chain retention, but will one type have a benefit over another in my case, and will/should it affect what type of chain I use? Cheers!

Relates to width of the chain – SS chains are 1/8", derailleur chains 3/32", so go for 3/32".

You want 3/32.

Someone more eloquent can explain why.

6/7/8 speed is 1/8 spacing, 9 is 3/32 10 and 11 are smaller again. You still need your chain to slide onto the 9 at the back so you can't use a fat BMX style chain. 3/32 for you.

Aren't 9 speed 5/64" wide???

3/32" is 5, 6, 7 or 8 speed. 1/8" is not for derailleurs.

Midlifecrashes is definitely wrong!

Super, thanks guys. Now I just need to find somewhere with a 32T 3/32 Uno in stock 🙂

I have 3/32 singleseed chain, its not chamfered for cog swapping but is lighter than a 1/8 and fits in a sts tensioner. (cheers charlie bikemonger).

If you are running 1 x 9 you just need a normal nine speed chain though as it still needs move up and down a cassette.

Agreed, I'm talking bollocks this time. You still need a 9 speed chain to suit the rear cassette.

But will the 9-speed chain happily sit on the 3/32 ring?

Surly suggests not with their rings. Maybe the OP should give Middleburn a call to be sure!

Check with Sheldon

IME 9s chains work on 8s (i.e. 3/32") chainrings fine.

It's not so much the tooth width thats the issue, its the width of the chain that causes the problems – if it's too wide it wont fit down the sides of the gear, so smaller generally is ok (tooth width should remain constant or wear would become too great), but larger may not be. Stick with whatever chain was meant to be run on your cassette and you'll be fine.

Ooh plot thickens. I'm calling Middleburn 🙂

What a jolly helpful chap at Middleburn. I absolutely need to run 3/32 Uno and a regular 9sp chain apparently.

Enjoy!

Now you can be sure that this won't happen:

Good effort!

🙂

I threw my chain at Cwmcarn which got caught down the side of the hub flange. I came to an abrupt halt and then had a little walk! It was nice and easy to straighten that ring though, but a shame about the marks on the hub and loss of paint from the frame…

Nice mauling there, good job!