Chain Keeper Fit Guide
The original Chain Keeper is designed to clamp around the seat tube of a frame, much like a front derailleur with a band clamp. The seat tube where the clamp mounts must have a circular profile and a diameter of 28.6mm, 31.8mm or 35.0mm [+/-0.5mm].
The seat tubes of some frames flare out and become larger before meeting the bottom bracket shell. In order to be compatible with the Chain Keeper the seat tube must remain straight and circular for at least 20mm below the topmost point of intersection between the chainring and the centerline of the seat tube.
If your frame does not meet these requirements the clamp mount Chain Keeper will not fit.
The chain block can be positioned side-to-side to match a chain-line anywhere between 33mm and 62mm, as measured from the centerline of the frame.
The seat tubes of some frames flare out and become larger before meeting the bottom bracket shell. The Chain Keeper cannot clamp around tapered or non-circular tubing. A Chain Keeper Extension may help to raise the clamp to a higher section of tubing with a straight circular profile.
The Chain Keeper BB attaches to frames with outboard bottom brackets. This allows the Chain Keeper BB to be used with full suspension frames, carbon fiber frames and frames with non-standard tubing.
The Chain Keeper BB is attached by a 2.5m thick mounting plate that replaces a spacer found on many external bottom brackets. Shimano Hollowtech II, FSA MegaExo and Truvativ Giga-X-Pipe bottom brackets are compatible so long as they include a 2.5mm spacer between the drive side bearing cup and the frame.
The chain block can be positioned side-to-side to match a chain-line anywhere between 42mm and 63mm, as measured from the centerline of the frame. In addition, the height of the chain block can be adjusted to work with chain rings ranging from 28 to 39 teeth.
The following table lists the spacer arrangement for most outboard bottom brackets when installed in either 68mm or 73mm shells. Hollowtech II, MegaExo and Giga-X-Pipe bottom brackets are designed to have their bearing cups spaced 75.5mm apart. The bottom bracket shell, 2.5mm spacers, and Chain Keeper BB mounting plate are counted toward the width total.
BB Shell Width |
Non-Drive Side (left) |
Drive Side (right) |
68mm |
2.5mm spacer |
Chain Keeper BB & 2.5mm spacer |
73mm |
No spacer |
Chain Keeper BB only |
If you have further questions regarding the compatibility of your frame with either the Chain Keeper or Chain Keeper BB, please email info@paulcomp.com, or call us at 530-345-4371.
