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The Clamp-On Single-Sided Chain Keeper is designed to maintain your chain on a Return or Power Idler. The single-sided and double-sided Clamp-On Chain Keepers are T-Cycle exclusive products. Nowhere else will you find a chain keeper that clamps onto the head of an idler bolt. Clamping on means freedom to easily float your idler, now that the chainkeeper attaches itself independently of the idler. It also means super easy setup and maintenance- you can pop the chainkeeper off and back on anytime. The abrasion resistant nylon arm, stainless steel fasteners and high quality machined aluminum means your Clamp-On Single-Sided Chain Keeper will be with you a long time.


1. Why this chainkeeper?

We developed these clamp on chainkeepers to enable idler float and to make everyone's lives simpler. Since the chainkeeper attaches itself to the head of the idler bolt, it is completely independent of everything else. That means the idler bolt can be tightened without squeezing the idler or chainkeeper. This allows the idler to float side to side with the chain for better efficiency. Also, since this chainkeeper clamps itself on, you don't have to put it on until everything else is done- very handy for maintenance. Install the idler and any spacers needed to keep it from rubbing on things and tighten the idler bolt. Lay in the chain, and THEN install the chainkeeper. How easy is that?

2. How does it work?

The chainkeeper is machined with a clamp sized for the head of an 8mm Socket Head Cap Screw (the standard idler bolt). A super abrasion resistant nylon arm, with a 5mm stainless bolt all the way through it, keeps the chain from getting any ideas of going places it shouldn't. To install the chainkeeper, simply slide it onto the head of the 8mm bolt and tighten. It's that easy.

3. Can I use it on other bolt sizes?

Yes, but. The clamp is machined to fit an 8mm Socket Head Cap Screw. For kits that have larger bolts, we turn down the bolt heads to the right size. For smaller bolts, there are things you can do with adapters and shims. We do such things on a custom basis.


  • CNC machined from a single piece of 6061T6 aluminum. Clamp is sized for an 8mm Socket Head Cap Screw (the most common recumbent idler bolt). Chainkeeper arm is a special abrasion resistant Nylon with a 5mm stainless bolt all the way through it for support.
  • MDS Nylon chainkeeper supported by m5 stainless bolt. Clamp designed for 8mm Socket Head Cap Screws with 0.52 inch (13mm) diameter heads. These chainkeepers can be used on other sizes of bolts, but larger bolt heads need to be turned down to 13mm and on smaller bolts or shafts a shim is needed to get up to 13mm.
  • Install idler and any spacers and tighten the idler bolt. Lay chain into idler(s), then slide chainkeeper onto head of bolt. Adjust angle of chainkeeper as desired, then tighten chainkeeper clamp bolt. To service chain or idler, simply loosen the chainkeeper clamp and slide off.
  • Any bike or trike with an 8mm idler bolt, and with a few modifications, other bikes and trikes with different types of idler mounts.