Hello again,

Further to my other fascinating thread about going Shimano 12speed. I’m current running a Middleburn Rs8- Xtype with a spider/32t Rideworks chainring on an 11speed Sram set up. The frame is boost and I assume the current setup is non-boost, clearance to the chainstay is tight…but hasn’t cause an issue.

So, what chainring do i need for my 12speed?Boosty or no?

https://www.mountainbikecomponents.co.uk/product/uno-x-type-boost-thick-thin-32t-hc/

I did email betd last week(on several contact addresses)…but didnt get an answer :/

Thanks

self bump for the weird forum….

Shouldn’t the same 11 speed chainring still work?

Apparently not

https://rideworks.cc/shop/narrow-wide-chain-ring/

If your cranks only just clear the frame I’d think the boost version of the middleburn one?
…or buy a longer axle to make it a boost chainset if needed, though the current specs suggest it is one.

https://www.mountainbikecomponents.co.uk/product/rs8-x-0003-73-mm-2/
THESE ARE THE AXLES AS FITTED TO THE X TYPE CRANKS. THESE BEING THE RS8, RO2, TANDEM X TYPES AND THE RS7 X TYPE AND THEY ARE FULLY CNC MACHINED FROM 7075 HERE IN THE UK.
EACH TYPE OF CRANK REQUIRES ITS OWN SPECIFIC LENGTH OF AXLE AND THESE ARE LISTED AS BELOW –
138MM – STANDARD RS8 X TYPE FOR 68/73MM BB SHELLS
THE RS8 CRANKS ARE SUPPLIED WITH A 138MM AXLE AS STANDARD. IF YOU HAVE ANY ISSUES FITTING YOUR NEW CRANKS PLEASE CONTACT US JUST IN CASE YOU NEED A SHORTER AXLE AND THESE ARE EASILY EXCHANGED AND FITTED.

Isn’t the difference in chain line only something like 2-3 mm? I’d just try it and see with the existing ring before committing cash.

Boost is all in the chainring or spider, nowt to do with axle length.

Boost chainrings are offset by 3mm outboard compared to non-boost.

However MTB chainline favours the bottom end of the cassette to get tyre clearance (big 3.0 plus for boost) and chainstay clearance for triple chainsets.

So running a non-boost chainring on a boost frame with a boost hub actually results in a better chain line for the most frequently used top end of the cassette. So if you aren’t having chainstay or tyre clearance issues then you have a more optimal setup and should see better chain life.

Some makes of 12 speed narrow wide chainring are narrower than their 11. If your chain locates fine on your ring and doesn’t seem stiff or cling to the ring then carry on as you are.

https://www.wolftoothcomponents.com/pages/boost-chainline-and-chainrings

If you are running 12 speed, the clearances are so small between chain and cassette that you MUST run a boost spaced chainring with a boost spaced bike. If you don’t, the chain will “tick” on the next bigger cog when in the smallest 2-3 cogs on the cassette.

According to this if running 12 speed i gotta run boost..

Really wish Betd would answer my chuffing emails :/

What bike is this going on?

This one….my Swarf Contour(you can see the aforementioned Middleburn crank)

The boost UNO is what you need, we run one on our tandem cranks with an Gx Eagle 12 set up with a boost rear end. As said above the boost is added in the ring design.

Boost

Just a thought – I’d leave out the Shimano chain from the setup and use Sram. I’m running Sram boost cranks with a Shimano hg12 compatible chainring and the Shimano chain was just really noisy and hated mud / grit / wet etc. Swapped for a Sram xx1 chain and it’s just so much better all round. The quick link on the Shimano 12 speed chain is also really picky about what chainrings it works with properly.

I’ve just put Sram Gx eagle on my other bike and so far I like it more than the Shimano Xt 12 speed on my full suss. Runs quieter and it’s a lighter downshift. However I need to give it time to see how durable it is – the xt has been slogged through the winter slop so thoroughly tested. Although I have had to dismantle the derailleur to service the pivot as it was full of mud / rust etc. Never had to do that with a mech before – I reckon 12 speed with a wide range cassette is really pushing the limits of the derailleur system in general.