Changing from 3x9 to 2x9 with a bashring

[willemjnaude]

Hi Hubbers

 

I want to pose a question to those more informed than myself: I am curretly running an XT crank 3x9 on a Scott Genius 20, but the middle and inner chainrings are due for replacement soon, and I am toying with the idea of dropping the big ring for a bashring.

 

My thoughts are as follows: I rarely use the big ring unless I am on hardpack gravel, and prefer to spend my time on more technical trails than long slogs for hours on end. And I keep buggering the (expensive) bigring on rocks etc.

 

Now.....

What sizes do i try? (I am eyeing Blackspire 24t and 38t with the bashring up front)

Can I keep the long cage RD? Or does this change require other drivetrain components to be changed? (other than the chain and setting limits on the FD)

 

Any input will help...thanx

 

This is what i'm thinking of doing

 

http://fcdn.mtbr.com/attachments/trek/607845d1302395190-post-your-fuel-ex-official-post-fuel-ex9-april-2011.jpg

[Brian Fantana]

I changed fro 3x9 to 2x9 on my trail bike. Also on an XT crank.

 

What I purchased:

 

1 x 38T Blackspire Super Pro chainring 104bcd

1 x 26T Blackspire Super Pro Chainring 64bcd

1 x Blackspire Stinger chain tensioner(optional)

 

What I did:

 

1. Took my old 42 chainring, and turned the teeth off on the lathe, gripping it on the inside with a 4 jaw chuck. This made a nice bash guard.

 

2. Fit new chainrings and bashguard. Bashguard on outer ring position, 38T on middle blade position, and 26T on inner ring position.

 

3. Adjust FD clamp height.

 

4. Adjust FD limit screws

 

5. Fit chain guide ( optional)

 

6. Ride the living daylights out of your bike.

 

Step 6 is the most important step, and it is advised that you carry it out as much as possible.

 

 

[Captain Fastbastard Mayhem]

Bear in mind that your big ring must not be bigger than 1.5 times your small ring. Iow - 28 small, 42 big.

 

 

[madmarc]

Hi Hubbers

 

I want to pose a question to those more informed than myself: I am curretly running an XT crank 3x9 on a Scott Genius 20, but the middle and inner chainrings are due for replacement soon, and I am toying with the idea of dropping the big ring for a bashring.

 

My thoughts are as follows: I rarely use the big ring unless I am on hardpack gravel, and prefer to spend my time on more technical trails than long slogs for hours on end. And I keep buggering the (expensive) bigring on rocks etc.

 

Now.....

What sizes do i try? (I am eyeing Blackspire 24t and 38t with the bashring up front)

Can I keep the long cage RD? Or does this change require other drivetrain components to be changed? (other than the chain and setting limits on the FD)

 

Any input will help...thanx

 

This is what i'm thinking of doing

 

http://fcdn.mtbr.com/attachments/trek/607845d1302395190-post-your-fuel-ex-official-post-fuel-ex9-april-2011.jpg

 

thats a funny SCOTT

[willemjnaude]

@ Brian....should I expect chain slap issues if I skip the tensioner route?

Thanks for the input.....CRC is like a disease...think I'll go the blackspire route. So, I need to pair a 104bcd with a 64bcd? (I'm asking cuz I haven't got a clue...)

[Captain Fastbastard Mayhem]

So if you're going 24 u can go no more than 36.

[Captain Fastbastard Mayhem]

@ Brian....should I expect chain slap issues if I skip the tensioner route?

Thanks for the input.....CRC is like a disease...think I'll go the blackspire route. So, I need to pair a 104bcd with a 64bcd? (I'm asking cuz I haven't got a clue...)

Chain slap yes. Easily fixed with garden hose and a few cable ties (look on the mcguyver thread)

 

And yes to the 2 sizes. That's normal shimano. Unless yours is xtr.

[Brian Fantana]

@ Brian....should I expect chain slap issues if I skip the tensioner route?

Thanks for the input.....CRC is like a disease...think I'll go the blackspire route. So, I need to pair a 104bcd with a 64bcd? (I'm asking cuz I haven't got a clue...)

 

I ride a Shova so my chainstay is above the top section of the chain, which means reduced chain slap even without a guide.

 

But on occasion I have dropped my chain on the inside when I rail left hand berms with bumps in the berm. The chain guide eliminates that.

 

You will still get some noise from the chain slapping the FD though.

 

Regarding chainrings. Yes, 104 bcd will fit the outer and middle tabs, while a 64 bcd will fit on the inner ring holes.

[Brian Fantana]

So if you're going 24 u can go no more than 36.

 

+1

 

If you go 38, you should take 26 inner ring.

[willemjnaude]

OK.....so a 24t/36t it is then...until I have the legs for a 26t granny

 

If I start dropping the chain I can add a tensioner, but until then the sock will have to protect the chainstay

 

One last thing: ordering from CRC is obviously subject to import duties (I know there are various threads on this, but I just have one uncertainty): If taking the DHL postage option, to whom are the duties payable? Does DHL inform you and you pay customs, or how does it work?

 

Shot alot for the help...been pondering this for weeks now

[Captain Fastbastard Mayhem]

Dhl will furnish you with an invoice, you pay them they pay SARS.

[willemjnaude]

Sounds simple enough....i should start hiding the credit card