In addition to the Shimano Dura-Ace R9200 Di2 group on the scale, Fair Wheel Bikes also had something else to share with us this week. Namely, a 12-speed road drivetrain with components from four different manufacturers. The result is a very light Open Up with an interesting mix of drivetrains.
Why would you want to combine these different groups rather than selecting one complete drivetrain? According to Fair Wheel Bikes, it was all about that gearing.
“We just finished an Open UP gravel bike which on its own is nice but what makes this one special is that we mixed Dura-Ace 12 speed and SRAM XPLR/Red stuff to get a good gravel gearing. We also tested different cranks and rings with the Dura-Ace stuff to see what worked and what didn’t. Ended up with a 48/33t [chainring] and 10/36t [cassette] for gearing, which in my mind is pretty ideal for gravel.”
- Open Up Frame (Small)
- Cane Creek AER headset
- Carbon-Ti top cap
- Lightning cranks 165mm
- Carbon-Ti Rings 48/33t
- Carbon-Ti chainring bolts
- HSC Ceramic Bottom Bracket
- Shimano Dura-Ace R9200 derailleurs, levers, brake calipers
- SRAM RED Flattop chain
- SRAM Force Xplr 10-36 cassette
- Carbon-ti Centerlock hubs
- Enve G23 Gravel rims
- Sapim Cx-Ray spokes
- Carbon-Ti thru-axles
- Carbon-Ti rotors 140/160
- FSA K-Wing AGX handlebar
- Mcfk carbon stem
- Specialized S-Works Phenom saddle
- Cane Creek eeSilk+ carbon suspension seatpost
- Panaracer Gravel King SK tires 700c x 38mm
- Fair Wheel tubeless valves
- Fair Wheel bottle cages
I still don’t see why Shimano didn’t integrate a clutch into their new Di2 stuff. It doesn’t affect the “feel” of the shift since it’s electronic but would provide some extra chain retention for gravel use if you wanted. Especially since GRX didn’t get the 12-speed upgrade.
I would guess it was due to friction concerns. There were those tests that showed that when shifting to a larger cog, the clutch doesn’t release the cage to the same point that a standard design would, so the lower run of chain will have more tension, and thus more friction. Hitting a bump that overwhelms the clutch, and causes the tension cage to spool back on the rebound, will bring it back to the normal, non-clutched tension, as will shifting to a smaller cog, but on the road those events may be fewer and further between. I would assume that is also why SRAM switched to a fluid damper rather than a solid friction source, when they introduced a clutch on their road groups, as it would presumably just slow, rather than fully arrest, the cage settling into the normal tension position following a shift to a larger cog. Not saying Shimano couldn’t do something similar, but perhaps patents and development time made it impractical.
A Shimano road group with a 10t!!! Why don’t the new GRX &/or Dura-Ace groups take advantage of the not-even-new-any-more micro spline freehub to go 1x? There’s so much more potential for TT and Gravel and 12. Shimano is really behind the times on this one. They have all the tech on the books, just not put together to full potential.
For TT? Why in the world would you want a 10t cog for time trials? So you can waste more energy as friction?
They just need to shrink both chainrings by about 10T and the drivetrain might make some sense. 38×24 with 11-34/36 should be about right. 10T cogs make sense to get more range out of 1x, or to lock people into proprietary parts with AXS, but otherwise not so much. Sigh.
Having tried the clutch on an XTR Di2 mech I can tell you that it does impact shifting feel.
@Sean there is no “shifting feel” on Di2. You press a button and it shifts the derailleur for you. It requires almost no effort on your part. It may affect the shift itself, but it is in no way fed back to the way your shift “feels” because there is no direct feedback from the derailleur to the shifter with an electronic system.
Come on, no free spin on the cranks to see that quality Open bottom bracket shell?
10-36 isn’t XPLR. 10-44 are the XPLR cassettes.