When I read in Mark Beaumont's fascinating account of his ride down the length of Africa, that his electronic gear-changing had stopped working, I was a bit scornful.  Electronic gear-changing on a touring bike, through countries where you could be hundreds of kilometres from anything resembling a bike shop?  As someone who comes from the steel frame, keep-it-simple-stupid school of touring cycles, it seemed a pointless luxury.

However it planted a seed in my mind and when my partner developed osteo-arthritis in her thumb joints, such that riding for a full day became almost impossibly painful because of repeated gear-changing, it set me thinking.  Drop-bar shifters, finger-operated, might work for some people but an old back injury rules out her using drops. Surely electronic gears, operated by push-buttons, might be the answer?

It took a lot of research, because there isn't a straightforward off-the-shelf answer, but we got there eventually and the system had its first real trial on a 1200 km tour of eastern and north-eastern Thailand in January-February 2018.  The system worked superbly, faultlessly throughout, and painful thumb joints were a thing of the past, at least as far as cycling is concerned.  So here is a summary of what I put together for her.

The bike

This set-up would apply to many touring bikes, but in this case it was a new Thorn Sherpa, and we took the bare frame to Ben Cooper at Kinetics in Glasgow for S&S couplings to be fitted.

The gearing

The first problem was that Shimano basically has two set-ups, one using a single or twin crankset, aimed at roadies, the other a triple, for mountain bikers.  Unfortunately neither offers the range of gearing needed for touring on a heavily laden bike.   The Thorn Sherpa had come with a triple on the front - 48/36/26 - and an 11-36 10-speed cassette on the rear, which with 26" wheels and 165 mm cranks, gave a lowest gear of 18.8 in and a top of 113.5 in.

However Shimano's front triple di2 deraiileur (FD-M9050) specifies a maximum of 40 teeth, fine no doubt for MTBs but no use for touring.  But digging around forums and blogs produced examples of set-ups running much bigger chainrings.  It would simply mean moving the mounting up the seat tube to suit, and not worrying about the fact the curve on the cage would not follow the chainring as neatly.  And clever though the di2 system is, it only knows you have a triple, it doesn't know what size rings you're using.

So for the front I settled on the M9050 deraiilleur and a 30-38-48 crankset (to suit max capacity of 18 teeth), compatible with 11-speed chains, from Spa Cycles.  Why 11-speed?  Well the di2 system offers a lovely refinement called 'synchonised shifting' where you can use a single (2-button) shifter switch to go through the full range of gears, with the electronics changing the front ring as well as the rear sprocket whenever necessary.  And the change points are user-programmable (see below).

For the rear I chose a Shimano Deore XT 11-40 11-speed cassette, CS-M8000, and that in turn meant a new rear wheel as the 11-speed cassette mounting is a different length from the 10-speed that was on the Thorn*.  Again I got the wheel from Spa Cycles.  The rear derailleur was the di2 RD-M9050-GS, which posed another potential problem as it specifies a total gear variation of 35 teeth, but this set-up was now 29 on the rear and 18 on the front, totalling 47.  Fortunately this is where the di2 system scores again, for by default it blocks out the two worst combinations (smallest chainring to two smallest sprockets) and it's easy to block off more than that.  Consequently it would be a simple matter to restrict the chainring-sprocket combinations to stay within the capacity of the derailleur. This all gave a lowest gear of 19.5 in and a top of 113.5, which she was happy with.

(*and I had another use for the old wheel, so didn't need to mess about with mating an 11-speed cassette to a 10-speed hub)

Selecting gears

The next challenge was what to use to operate the system?  I had expected to use the di2 MTB Firebolt shifter, SW-9050-R, but when it arrived it was clearly designed to mimic a mechanical one, with heavy spring loading that would pain my partner's thumbs in the same way.  Drop-bar shifters were out, and some of the other di2 shifters only work as plug-ins to drop-bar levers.  However the SW-R671 Aero/TT shifter looked promising.  It's meant to plug into the end of a tri-bar, but it wasn't too difficult to fabricate a mounting, using a section cut off an old handlebar, a block of wood shaped to hold it parallel to part of the bike's handlebar, and a re-shaped jubilee clip to hold it all together, a coat of black paint going some way to hiding the Heath Robinson nature of the mounting.  An advantage of that was that it was easy to adjust its position so that she could operate the two buttons easily with her fingers (not her thumb).

Installation - derailleurs and cablesfront derailleur

I was reluctant to go for an external battery and wiring, both for reliability while touring and to minimise the attraction to thieves, reasoning that the more the system was concealed the better.  However the Thorn frame did not have sufficiently large holes around the bottom bracket to use Shimano's recommended installation, which sees the 2 derailleur wires, the battery wire and the wire to the front end all coming together in the 'junction B' connector which is then stuffed up the bottom of the seat post.  A chat with Ben Cooper (Kinetics) produced a neat answer, which was to make use of the lower S&S coupling to stuff the battery up the down-tube and put the junction B adjacent to it, with the wires emerging through custom holes that he created, with brazed reinforcements.

I first connected up the derailleurs, battery, junction B, handlebar display (9500) and switch, all off the bike, then charged up the battery and tried it out.  It all worked beautifully so the next step was to install it for real.  The rear derailleur fits as any rear derailleur would, but note that it has a bronze coloured lever which should be in the OFF position until installed and the wheel is in place, then moved to the ON position. This is because the di2 derailleur spring is a lot stronger than a mechanical derailleur - moving that lever to the OFF position makes removing and refitting the rear wheel a bit easier.

A di2 wire ran along the chainstay, protected by Shimano's own wire sheath, and given extra support with a couple of small cable-ties, round to the access hole and into the bottom end of the down-tube, choosing a route that minimised the risk of any damage in use.

Similarly the I fitted the front derailleur, adjusting its position to as near ideal as possible, given the slight mis-match (as noted above) between cage shape and chainring size.  I chose a top-mount clamp but a bottom-mount clamp would work equally well - it just depends on your bike frame, and in particular if you have any bottle-mounts in the way of either clamp.  That wire similarly fed down the tube an in through the same access hole

Front wire, battery and junction B

I fed a long wire into the down-tube and down to the S&S coupling, then pushed the battery, with its wire attached, up the tube.  All 4 wires, from the rear derailleur, front derailleur, battery and front, then plugged into Junction B (in any order).   I also modified a pair of ordinary tweezers to make a tool that would allow me to grab the battery, using the groove at its bottom end, and remove it if ever necessary.  Finally I carefully stuffed the wires and junction B into the lower down-tube and put the two parts of the frame together, tightening up the S&S couplings.

Handlebar fittings

di2 shifter

The front wire I took to the wireless adapter, mounted under the stem, with another wire to the handlebar display, which also takes the wire from the selector switch.  With a bit of tidying up using cable spiral wrap, that completed the installation.

Setting up

Many descriptions of the di2 system bemoan the limited capability of the SM-BCR2 charger for internal batteries, which connects to a PC but supposedly doesn't allow you to customise the system.  Well that may have been the case, and if so then Shimano has relented because I found that was all I needed to update firmware, allocate functions to switches, and above all to customise the gear-change program.  There are still a few things, like interrogating error messages, that require the much more expensive PC interface, but mostly they will only concern dealers, and so far I've not needed it.

Once all the firmware had been updated, I found the 9500 display seemed to have all the capacity of the later 9501, and was able to set about the adjustments, and this revealed more problems.

At the rear, there is a range of adjustments to line up the chain with the sprockets by shifting the derailleur but I was concerned to find that I was right at the limit of adjustment.  After a close examination and a bit more research, I realised that the axle had a rather thick washer pushing the cassette away from the derailleur, and swapping it for a thinner one (still a proper Shimano axle washer) meant things lined up rather better, close to the middle of the adjustment range.

The front was worse, with the middle chainring nowhere near lined up even at maximum adjustment, and it was clear I needed a longer axle.  The bottom bracket was an 80mmx 112, and by unscrewing the bracket until the chainring lined up I could see I needed about 5mm more on the crank side, and obviously the same on the other side, ie a bottom bracket of 80 x 122, which did indeed give me perfect alignment.

With everything in place, it only remained to test it on rollers, first by hand then pedalling, and it was a revelation, smoother and sharper than I'd imagined possible.

Long-term trial

Out on the road it became apparent that it was changing too readily from the middle to the larger chainring, so I re-programmed it to stay on the middle until all those gears were used up, and it only occasionally goes onto the large ring for the fastest sections, or the small ring for the climbs.  

Other than that, in hot, dusty conditions in Thailand, on roads that varied from good tarmac to loose gravel and sand, it performed faultlessly over 1200 km, and didn't even need a battery charge.

Other observations

My partner never used the handlebar display at all, happy to simply shift up and down until one or other limit was reached.  I considered swapping it for a simple Junction A box but found, again contrary to info elsewhere on the internet, that it doesn't allow you to select synchronised shifting, so the display stays.

As well having the e-tube app on her phone, to customise the system, I took along a Windows 10 tablet with the e-tube Project software, and the charger/interface, but as it turned out, the system needed no attention at all.  Still I'll do the same for future tours.

I had a second selector switch so she could have one on each handlebar, and the option of operating in non-synchronised mode, but we never used it, though again I'll take it along as a spare.