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This family of heavy duty frame clamps can be used anywhere you want to clamp something securely to a large diameter tube. Machined from 5/8 inch (15.9mm) thick aluminum, it uses beefy 6mm stainless bolts for significant clamping power. Clamps are currently available in three sizes: 1.75 inch, 2.0 inch, and 60mm. These are the most common recumbent main tube sizes. We plan to make additional sizes for additional purposes in the future, so check back with us if you need something in a different size. Each of these clamps is designed with one low profile side and one higher profile side with two m6x1.0 threaded for attaching your accessory. When used with the SeatSide Mount system, two Y clamps are attached to hold another tube 90 degrees from the main tube. For mounting batteries, racks, or other things, use the two 6mm threaded holes to attach whatever you'd like. For extra stability, use a pair of clamps.


1. What are these things for?

They are for attaching things to big round tubes, like the main tubes of recumbents. They are very strong and can be used to attach heavy things like seats, batteries, racks, special needs fixtures, etc.

2. I get how they attach to a tube. How do you attach things to them?

There are two 6mm threaded attachment holes surrounded by a flat surface. Depending on what you are attaching, you may need spacers on the 6mm bolts. For example, to attach a plate, you would need two 6mm holes in the plate, two 6mm bolts, and spacers or washers to go between the plate and the clamp.

3. How is this different from the other clamps you make, like the Idler Mounts and the Cargo Monster Clamps?

There are several differences. The biggest is that these clamps are heavier duty. They are 5/8 in (16mm) wide instead of 1/2 in (12.7mm) wide. They clamp to the tube with 6mm bolts instead of 5mm bolts. These clamps are currently available in only the three most common main tube sizes, the other clamps are available in lots more sizes.

4. What sized tubes can you attach to?

Currently, 1.75 inches, 2 inches, and 60mm (44.5mm, 51mm, and 2.37 inches).


  • Clean the area of the tube where the clamp is to go to remove any grit or oil. Attach the clamp in the orientation required, and tighten the bolts evenly. Attach whatever you'd like to the clamp with 6mm bolts.
  • These clamps are designed for heavy duty clamping. They are low profile to reduce the possibility of interference with things like chains, cables, etc. We make other less beefy clamps for attaching things that don't require such clamping power.
  • Machined from 6061T6 aluminum, black anodized. All fasteners are stainless. Clamps are 5/8 inch (16mm) wide. Holes for attaching other things to the clamp are m6x1.0 internal thread, with a maximum depth of 1/2 inch (12.7mm)
  • Anything with a 1.75 inch, 2.0 inch, or 60mm round tube.