BK Xray

Will the SRAM dual drive rear hub hold up to use on a tandem? I am preparing to buy a recumbent tandem trike with 20" wheels. I like the lower gearing for the hills it gives us, but it would be nice to pick up some higher gearing as well. A builder I am considering offers the dual drive but I wasn't sure it would handle the extra torque of a tandem. Any thoughts or experience on this?

TandemGeek

Refer to Page 18 of the linked document:
https://www.sram.com/_media/techdocs/...ns_E_12_02.PDF

Specifically, take note of the following entry under Technical Data:
Tandem compatib. Not suitable for tandems and delivery bicycles

merlinextraligh

Bike Friday uses SRAM DD on some of their tandems. We have one, and haven't had any problem with the hub. However, I would note most of the miles on that bike have been put on by myself and my then pre teen daughter.

Retro Grouch 

I have some personal friends who own a Bike Friday triple that uses a SRAM dual drive system. To my knowledge they have had no problems with the hub gears.

The flanges on that hub are rather tall. My recommendation is to build the wheel cross 2 to reduce the angle that the spokes enter the rim. They popped a lot of spokes at the nipples until I rebuilt their wheel that way.

bentbaggerlen

The Dual Drive hubs have been used on many of the Bike Friday tandems, as well as a few Greenspeed tandem trikes, I only know of one that failed. But like TandemGeek pointed out it is not approved for tandem use. So if it fails during the warranty, Sram dose not have to cover it. (Thats if they even know it was on a tandem)

Have you looked into a speed drive bottom bracket? Its a two speed bottom bracket that replaces the stokers bottom bracket. See https://www.schlumpf.ch/sd_engl.htm for more info.

The last tandem trike I built up ended up with this gearing using all standard off the shelf parts. The trike was built up for loaded touring so the taller gears did not see much use.

Gear inch
granny mid top
26 48 60
11 47.27 87.27 109.09
12 43.33 80.00 100.00
14 37.14 68.57 85.71
16 32.50 60.00 75.00
18 28.89 53.33 66.67
21 24.76 45.71 57.14
24 21.67 40.00 50.00
28 18.57 34.29 42.86
34 15.29 28.24 35.29

BK Xray

Bentbaggerlen- how were you able to go with such a wide range up front? Did you have any problems with shifting? That seems like it would be an ideal set up with 20" wheels though. Was that on the Troika?

bentbaggerlen

Yes that was on the Trokia, It shifted ok, nothing great but it was serviceable on tour. I shifted the front with a Deore XT deraileur with bar end shifters set to the friction mode. The shifting could have been better if the middle ring had ramps and pins at times the chain could jam when shifting from the middle top the big ring if you shifted too slowly.