BMC AlpenChallenge goes DI2 -part 1

Shimano ST-R785

Shimano’s Ultegra mechanical hydraulic STI levers (685) are ok, but the di2 (785) version is just amazing. Better braking and way better shifting.  They do rattle more, but to me that’s less of an issue, even though a complete silent bike just rocks.

Just like on the Niner, the holes in the bottom bracket to the seat tube and the down tube are too small to fit the di2 junction box. So here I’ll have to slide it down the seat tube as well. This means making sure the cables from the rear derailleur to the junction box and from the junction box to the head unit must account for the additional length of the seat post – to get them plugged in.

Some minor drilling was required.

That initial hole was just a mm too tight for the di2 connector.

I could still run mechanical 1x which I’m running now anyways…

Drilling out the cable stop.
Threading the needle.

All that’s left now, is decide whether I want the ultegra medium cage or – like the Niner – an XT derailleur.  The weak spot on this bike is the derailleur hanger, and the extra tension from the clutch tends to bend it too quickly.  For regular and shorter cx/gravel rides, the 11-32 (or 3T’s 9-32)  cassette paired to either a 42t or 50t chainring should be ok.  Ultegra it is then.

Got some cables, derailleur and junction box to order now…

One Reply to “BMC AlpenChallenge goes DI2 -part 1”

Leave a Reply

Your email address will not be published. Required fields are marked *