Front freewheel DIY chain guide.

Feb 8, 2019
South FL USA
Some people add front motors and drive them through a front freewheel like the ENO. Another situation is disabling the rear freewheel to use the front one in a mid drive to allow shifting w/o pedaling. The ENO needs a straight chain line due to it's one row bearing, and the front freewheel needs a low friction guide to place the chain onto the chain ring in an overrun situation. Any friction form a solid guide, or front derailleur cage will make things worse. Cross chained bikes will benefit form this solution also. Hats off to the guys with milling machines who can make their own stuff. But there are off the shelf parts that can do this also.
Part #1 The Terra Cycle 15t Sport idler. 8MM shaft to run next to a big mid drive. Options for 10mm bearings for bigger stuff. Steel cog and double 608 bearings.
Part #2- The Terra Cycle battery mount frame clamp. The idler clamp they sell is too weak. The battery clamp comes in many sizes to fit various frame tubes and uses 2x 6mm bolts to attach the load to it.
part #3 T-Cycle spacer kit. get a couple jam nuts and ss washers form the local hardware also. An 8x50mm allen bolt will have enough unthreaded shank for the bearings to run there. The T-Cycle bolts are cut too short for fine adjustments.
The DIY part- A piece of 3/8"x1" or 3/8"x 1 1/2" Aluminum bar stock. (My local metal supplier has no minimum order and sells by the pound and the first cut to length is free.) Drill 2-1/4" holes 1.97" apart centered 1/4" in from the edges starting at one corner. This will bolt to the frame clamp, and is reversible up and down.
The drill and tap the 8mm hole in the opposite corner centered 8mm in from the edges. The offset can help clear water bottle bosses on the frame if needed. The 1 1/2 inch size allows more offset, or angle drilling to be level when mounted on a seat tube. A few minutes on a drill press is all it takes for this
This part can handle wheels up launched on a 1500W BBSHD. I broke a lot of other stuff before coming up with this.
Pictures in this thread.
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