Di2 GRX Build Big Shopping List / Wheels / Dropper Post Advice

petemadoc

My cross bike is showing it's age and I fancy building up a completely new bike. Usage is do anything, just leave the front door and hit any road, track or trail.

Frame will be Dolan GXC (27.2 seatpost)- https://www.dolan-bikes.com/gxc-carbon-gravel/

Never used Di2 - just about getting my head around it and have settled on GRX 2x11. Doesn't look like I can just buy the whole groupset off the shelf so it's a case of finding what I need in stock and buying all the fiddly bits.

Shifters, brakes, derailleurs, chainsets all sorted

Di2 list of bits so far - does this look correct?

BT-DN110 battery internal
EW-RS910 Junction
EW-WU111 Di2 ANT+ transmitter
SM-BCR2 Di2 charger
Various wires
Think I need another junction but not sure which

I've also seen various methods of keeping things rattle free inside the frame. Definitely don't want rattles! What's the deal here what do I need?

Rotors - just stick with shimano RT800, any other offerings to look at? Build quotes up 140 and 160mm.

Wheels - would like something robust and a bit bling, budget approx £450

Dropper post - really like the idea but don't want to add too much faff and bulk. Would have to be 100mm drop to be worth it.

Any experience and advice welcome. TIA

BetterShifting_Terry

Sounds like a nice project!
The very least you will need to run Di2 are:

• Junction A (SM-EW90A / EW-RS910 / SC-MT800)
  
• Any shifters (in your case probably the GRX shifters)
  
• One derailleur (if you use two deraileurs they must be from the same category. Road/GRX vs MTB)
  
• The charger, SM-BCR2
  
• EW-SD50 wires to connect everything
  

A seatpost battery holder is pretty good too, but you can also use foam/cloth/whatever you like.

To stop thing rattling around you can use the Shimano cable ties. They basically clip onto the EW-SD50 wire and stop things from rattling. Part code EW-SD50-i.

The Shimano Dealer Manual is a great place to start: https://si.shimano.com/#/en/iDM/RX815 (as are the other documents on si.shimano.com). Also, my own page:

https://bettershifting.com/building-a-di2-bike-what-parts-do-you-need/
https://bettershifting.com/building-a-di2-bike-cable-routing-lengths-and-wiring/

;-)

BetterShifting_Terry

Oh.. I just realised.. if you want a dropper post then having the battery in the seatpost may not be feasible. In that case you can put it in the fork steerer (PRO make a Di2 battery expander plug) or in the frame.. probably..