CELEBRATING 25 YEARS // FOUNDED IN 1999

MTB CRANK & CHAINRING FAQ

HOW TO INSTALL CRANKS ON YOUR MOUNTAIN BIKE // Canfield AM/DH Cranks Installation Guide and FAQ

*PLEASE NOTE:
• Canfield cranks are SRAM GXP Compatible (will NOT work with DUB or Shimano bottom brackets)

• The NON-drive crank arm bolt must be tightened until the bolt fully bottoms, failure to do so will result in the crank arm coming loose shortly after riding.

What crank length should I choose for MTB?
Crank length is important for proper fit and optimal performance on your mountain bike. Canfield Bikes offers many different crank arm lengths (including some of the shortest on the market) ranging from 150mm all the way to 170mm in 5mm increments. This allows riders of all sizes and ages the ability to customize their fit.

As a starting point, we recommend the following lengths based on inseam:

Geared trail/AM/enduro bike: 20% to 20.5% of inseam length
Example: With a 32" inseam, Lance runs 165mm on all trail bikes. 
20% = 162.5mm, 20.5% = 166.6mm
Downhill Bike: 19% to 19.5% of inseam length
Example: With a 32" inseam, Lance runs 155mm on his DH bikes.
19% = 154.4mm, 19.5% = 158.5mm
Singlespeed: 21% to 21.5% of inseam length
Example: With a 32" inseam, Lance would run 170-175mm if he hated himself enough to ride singlespeed.
21% = 170.7mm, 21.5% = 174.7mm 

 
Are my MTB cranks too long? Are shorter cranks better?
With the current crop of ultra-low bottom brackets on mountain bikes, shorter cranks allow for a little extra pedal clearance in rough terrain. But there are other benefits to shorter cranks. They can actually
improve power and efficiency and help eliminate “dead spots” in your pedal stroke. Smaller riders and teens will also appreciate the ability to run shorter cranks on their bikes as they grow into new sizes. We have heard from many smaller riders praising us for the ability to actually get a bike to properly fit them thanks to the shorter cranks we offer. All Canfield MTB cranks are AM and DH rated for maximum strength and durability while being lightweight.  

Should I use a smaller chainring with shorter cranks? (Crank length and gear ratios)
A shorter crank arm is a shorter lever, so you have less mechanical advantage. When it comes to gear ratios, dropping 10mm in crank length (e.g. 170 to 160), is the approximate equivalent of going up two teeth in chainring size. However, you are also spinning smaller circles, which feel easier and negate some of the perceived increase in effort. So, you may want to try shorter cranks with your current chainring size, but if you want to keep the same gear ratio, you can go to a smaller ring.

Example: Final Gear Ratios Based on 29-inch Wheels and 51t gear on rear cassette.
• 170mm Cranks
      -30t front ring = 1.3/1 final gear
      -32t front ring = 1.4/1 final gear
• 160mm Cranks
      -30t front ring = 1.4/1 final gear
      -32t front ring = 1.5/1 final gear
• 150mm Crank
      -30t front ring = 1.5/1 final gear
      -32t front ring = 1.6/1 final gear

What width crank fits my mountain bike?
The two different sizes of Canfield AM/DH cranks refer to the width of the crank spindle which will correspond to the size of your frame’s bottom bracket width. The 73mm cranks will typically fit most all-mountain/enduro/trail bikes. Our 83mm cranksets typically fit downhill bikes. If unsure, please check your bike manufacturer’s specs.  

Do I need to use the included spacers when installing my cranks?
Canfield 68/73mm cranks will fit a 73mm bottom bracket without spacers. 68mm bottom brackets will require one 2.5mm spacer (included) on each side of the spindle upon installation.

Will Canfield cranks work with a press-fit bottom bracket?
All Canfield MTB cranks are designed for a SRAM GXP style bottom bracket. We have PF92 bottom brackets designed to work with Canfield Cranks available here.

What chainrings fit Canfield AM/DH cranks?
Canfield AM/DH cranks are designed to accept a SRAM three-bolt direct-mount chainring. We offer chainrings that are compatible with our crank sets, but there are many brands of chainring to choose from that are SRAM direct-mount compatible.

Current Canfield Cranks (2023+) are built to a standard offset, so most chainring manufacturer recommendations will be accurate.

• Non-Boost 142 frames: -6mm offset 
• Boost 148 frames: -3mm offset 
• Super Boost 157 frames: 0mm offset

Older Canfield Cranks (pre-2023) have a slightly different offset than most cranks, so required chainring offset will differ as well. 

• Non-Boost 142 frames: -3mm offset (normally sold for Boost frames)
• Boost 148 frames: 0mm offset (normally sold for Super Boost frames)
• Super Boost 157 frames: not compatible

My cranks are tight to install, how do I know when to stop turning the crank bolt? 
The NON-drive crank arm bolt must be tightened until the bolt fully bottoms. Failure to do can result in the crank arm coming loose during riding. The bolt will physically stop turning once completely tightened.

What is the torque spec for Canfield cranks?
65 to 70Nm. When new, may require up to 75Nm.