VaultGuru

Has anyone had experience installing a Jtek DropStop using FSA-SLK cranks on your tandem? This is the link to the unit:
https://jtekengineering.com/dropstop.php

I changed out the 28 tooth granny gear to a 26 tooth gear. The drop from the middle chainring is now 39>26. I am using a Campi derailleur with a long (triple) cage. I didn't have problems dropping the chain with the 28 tooth granny, but the 26 is more problematic. know that if I shift to the 26 tooth, under no chain tension, I can get a good shift. However, I have already dropped the chain twice with a small amount of chain pressure.

Prior to the install, I got 4-5 revolutions on the crank with a easy finger flick. Post install is about 1/2 revolution. The bearing cups and crank bolt are torqued to spec. The approximate thickness of the DropStop at the point of contact on the BB is 2mm. There is now pressure against the bearings. I am thinking that the aluminium cylinder that goes between the drive side crank and the transfer crank acts as a stop/seat for the cranks. The additional 2mm thickness of the DropStop does not allow the cranks to seat onto the cylinder. Therefore the cranks apply pressure against the bearings when the crank bolt is tightened.

Any thoughts on how to change the install to get it to work?
Thanks.

Chris_W

I used a Jtek Dropstop on a single bike with a Shimano triple crank, and that worked OK, but I can understand how it might not work on an FSA crank. Are there any non-drive-side spacers on the crank axle that you can remove? If the wave washer on the non-drive-side is totally flat then the system is not going to work as designed.

K-Edge make a chain catcher for triple-rings (see here) that mounts onto the derailleur braze-on mount, so you may be able to use that. However, it's not the best system since there is only the FD bolt pressure preventing it from rotating out of the way.

dubbelop

Does the Calfee's seat tube prohibit mounting the N-Gear Jumpstop? We run them on most of our bikes and are very happy with this nifty device. The tube doesn't need to be exactly round to get it to fit.

VaultGuru

Hello Dubbelop. Thanks for the input. The Calfee seatpost tube/bb integration design doesn't allow me to place a Jumpstop clamp that close to the bb.

VaultGuru

Hello Chris
Thanks for your suggestion and the link to K-Edge. K-Edge never popped up on a chain drop search. The Calfee has a clamp-on derailleur. I will check with K-edge, but I think their clamp-on chain catcher will work perfect. Will let you know What I find out.