Shims for fat bikes and ebikes with extra fat tires

Sondors recently released some additional customization options and upgrades for their fat bike ebikes, one of which is even larger tires (4.9 inches). Unfortunately this causes the tire to rub (very lightly) up against the bottom of the storage compartment of the bike seat. But not to worry, I figured out a way to cheaply make some heavy rubber shims from stuff at the hardware store to lift the bike seat frame up off the peg a couple millimeters, giving the bike seat enough clearance for the tires. This will of course also work for non motorized fat bikes as well as some 29'ers.

At the hardware store, you'll need to pick up a piece of 2 inch outer diameter / 1.5 inch inner diameter braided vinyl tubing, and 4 socket cap screws (M6x1.0, 30mm long). With a utility knife, cut a strip approximately 15mm wide from one end of the tubing.

Slice the tubing down the sides to make the shims. Each shim should be about an inch long. We want it to provide the clearance, but not interfere with the screws at all when installing them. You'll ultimately need two of these shims, one for each peg.

Once the shims are done, it's time to install it onto the pegs. Install the pegs onto the bike, and as you set the bike seat frame onto the pegs, position one shim under each "leg" of the bike seat. Make sure the shim is positioned directly on top of the peg. Use the longer screws that you purchased with the tubing to tighten the peg clamps down. The screws included with your bike seat are just a bit too short. Make sure the frame is seated cleanly on the shim (the shim isn't crooked or anything), and tighten the screws very tight. Note in the pictures below, I purposefully left it a little loose for exhibition of assembly.

I actually came up with this fix while on the road trip in Reno, while installing a bike seat onto a customers Sondors before he headed out to the playa. Unfortunately we forgot to take pictures after getting the bike seat installed, so I shot the pictures above in the hotel room.

​Alternatively, another customer with the same issue decided to use one of some extra rubber shims he had gotten with his Sondors, shims originally intended for mounting the screen onto the handlebar.

Very soon I'm going to start working on designing a custom shim specifically for Companion Bike Seat, and will make this available on our website once it's ready.