Does it feel like you’ve seen this post here once before? It’s because you have, but this one is different. This is my wife’s bike and it isn’t as simple as leveraging the DI2 to move to a mountain drive train. My wife is riding a Felt F3X with an Ultegra/RS685 mechanical drivetrain and hydraulic brakes. It’s a sweet little bike, but she wants to go 1x. She loves it on the mountain bike, so I figured why not.
The set up looks like this: 11-40T XT cassette and rear derailleur. The Ultegra crankset will be fitted with a Wolf Tooth 42T chainring. To adapt the shifting from the road to mountain pull ratios I’m going to fit a Wolf Tooth Tanpan. I have to use the inline version because of where the derailleur cable leaves the frame.
The Tanpan is genius in its simplicity. It is a pair of stacked concentric cable wheels of two different diameters. The shift cable wraps through these pulleys and essentially adapts the movement from the small pulley to the large pulley. As the small pulley moves with a shift, the large pulley takes up the needed additional cable as it rotates.
Only con I see with the Tanpan is specific to the inline version. On a cross bike wet conditions are always a concern. I don’t like having a break in the housing and the cable exposed in the middle of the run. It just doesn’t seem like a good idea. In my favor is the weather. We rarely have wet conditions. I did give the cable a nice coat of grease hoping it will stay-off corrosion for a while… I think this is less of a concern on that standard version because the exposed cable is at the end of the housing run (literally right where it would normally be exposed).
The mod was straight forward, remove the derailleurs, chain, and cassette. I unwrapped the tape and removed the cable from the left side of the bars. I cut the rear shifter housing right where it left the bar and place the Tanpan just under the stem. Installed chainring and the set up the rear derailleur as normal while taking in consideration the install instructions for the Tanpan.
What came off the bike:
- Ultegra 6800 rear derailleur – 198g
- Ultegra 6800 front derailleur – 104g
- Ultegra 6800 11-28T cassette – 244g
- 105 chain – 246g
- Ultegra 6800 34T & 46T chainring – 122g
- Misc cable housing – 24g
Total take-off weight: 938g.
What went back on the bike:
- XT M8000 11 speed derailleur – 274g
- XT M8000 11-40T cassette – 412g
- Wolf Tooth 42T chainring – 76g
- XTR chain – 242g
- Wolf Tooth Tanpan in-line – 18g
- Misc spacers – 6g
Total conversion weight: 1028g.
The modification didn’t work out 100% in my favor (+90g weight increase), but there are some benefits that out-weigh the .2lb increase. First, 1x. If you don’t get it already, you will at some point (especially for Cross). Next, the clutched rear derailleur is huge in my mind. In cross racing there is nothing as bad as bouncing a chain off or listening to your chain kick the snot out of your frame with every bump. The clutch makes all the difference. SRAM gets it, now if Shimano would get on board for their cross components it would be awesome.