BBs and Cranks

[Lance Roberts]

Hi,

 

I'm thinking about going from 2x10 to 1x10 on my crank. My problem is now figuring out which crank to go for according to the BB that I have on my bike.

 

I have a Scott Spark 910 with a BB92 and Shimano XT double crank in it at the moment. Would I be able to buy a, let's say, raceface single crank and run it on the same BB? Or would I need to do some sort of conversion? Is the axle on all cranks the same diameter?

 

There are so many different BBs out there, which makes it very difficult to figure out how to make things work.

 

I also don't want to convert my current crank to single, just in case I want to go back to the double at some stage. It's a lot easier to just swap the cranks in stead of removing or adding the gears...

 

Hope someone can shed some light on this for me.

 

Cheers,

 

Lance

 

[CAAD4]

I would think that removing the one chainring and getting a NW chainring with short crank bolts is the way to go. That way you can simply put the second one back on with the longer bolts.

[Lance Roberts]

I would think that removing the one chainring and getting a NW chainring with short crank bolts is the way to go. That way you can simply put the second one back on with the longer bolts.

 

Thanks for that. I guess going back to 2x10 would be a big job any way because of refitting the derailuer, re-cabling and all that...

Would I need a chain guide?

[NukeproofPeanut]

What my friends have done, is go NW, removing the derailleur and shifter but leave the smaller climbing gear on the crank.

 

They then just change the chain to it (with a finger) for climbing steep hills, but otherwise leave it in 1x10 mode on the NW for all other riding. No chain guide needed.

[popcorn_skollie]

What my friends have done, is go NW, removing the derailleur and shifter but leave the smaller climbing gear on the crank.

 

They then just change the chain to it (with a finger) for climbing steep hills, but otherwise leave it in 1x10 mode on the NW for all other riding. No chain guide needed.

How well has this worked? NW rings are thicker than normal chainrings. 

Clearence issues? surely the chain rubs the inside of the NW when using the smaller ring?

[CAAD4]

Thanks for that. I guess going back to 2x10 would be a big job any way because of refitting the derailuer, re-cabling and all that...

Would I need a chain guide?

 

Some say that a NW chainring and Clutch rd is all it takes, some say clutch is unnecessary. 

[Lance Roberts]

Ok, if I go for the RaceFace Narrow Wide, what size should I get to fit my XT crank?

What bolt circle size, and what is the common tooth setup used these days?

Also which gear does it replace, the big or small one?

[NukeproofPeanut]

How well has this worked? NW rings are thicker than normal chainrings. 

Clearence issues? surely the chain rubs the inside of the NW when using the smaller ring?

No issues, both raced Giba this weekend with me and they had no issues at all.

 

edit: Should clarify that they are using 32T NW on XT and deore 2x10 cranks.

[Amberdrake]

I like this going to put my small ring back! Helderberg farm on 1x10 is killing me(unfit).

[Odinson]

Then why not just refit the FD and shifter? What possible gain could you have from those few grams?

[Wolfie1]

On xt 3 blade crank you need a NW 104 bcd blade 30t or 32t on a normal 11-36 cassette

If you want to go all out .....My conv advice is buy a 40t cassette adapter, replace your 15t and 17t with 16 t sprocket and you 40t and run a 30t up front for hectic climbs.

You will bottom out on 40km per hour and still have a granny to bail you out. My 3blade xt crank is doing its service up front with no issues

 

This way you can keep you bb as it is now

[NukeproofPeanut]

Then why not just refit the FD and shifter? What possible gain could you have from those few grams?

So you can fit a dropper remote easier and keep the cockpit cleaner.

Also, having front derailleur is not #enduro!!

 

Additionally you would probably damage the NW if you try shift to and from it.

[Lance Roberts]

On xt 3 blade crank you need a NW 104 bcd blade 30t or 32t on a normal 11-36 cassette

If you want to go all out .....My conv advice is buy a 40t cassette adapter, replace your 15t and 17t with 16 t sprocket and you 40t and run a 30t up front for hectic climbs.

You will bottom out on 40km per hour and still have a granny to bail you out. My 3blade xt crank is doing its service up front with no issues

 

This way you can keep you bb as it is now

Thanks for all the info guys, it helped a lot!

One last question, will there be enough space to leave the FD on while the NW is on? Just so that I don't take all the cabling out, remove the FD and then discover after a few rides that I don't like 1x10...