Shimano di2 Electronic Gearing for a touring bike

When my partner developed osteo-arthritic pains in her thumbs, it became very difficult to use conventional mechanical shifters, especially those used on straight bars (she can't use drop-bars due to an old cycling back injury).  Touring for 6 to 8 hours a day was becoming close to torture.  So I started looking at electronic gear-shifting, and Shimano's di2 system seemed to be the answer, though not as straightforward as it seemed at first.

The first problem was that we wanted the option of synchronised shifting and that's only available with an 11-speed cassette, and her bike, a new Thorn Sherpa, had a 3x10 set up.  That was solved by a Shimano XTR 11-speed cassette, choosing 11-40 as that was the widest compatible with a front triple.

Second problem was that Shimano specifies a maximum chainring size of XX teeth, which is OK for mountain biking, but not high enough for touring.  However the di2 system doesn't know what size your chainrings are, just that you have a triple, and the front derailleur can simply be mounted higher up the seat tube to align with the larger chainring (the chain guide curve is not a perfect match, but it's OK - it works).  The XTR front derailleur has a capacity of 18, so I chose a 30-38-48 triple for 11 speed chain from Spa Cycles.

Third problem was that the total capacity of the XTR rear derailleur is YY but there's a neat solution to that.  The di2 system is programmable and by default it excludes the combination of smallest chainwheel with any of the 3 smallest sprockets - and that brings the overall variation in chain position within the rear derailleur capacity.

Fourth problem, and potentially a major one, was that the XTR bar shifters are designed to mimic the feel of mechanical shifters, which would put just as much strain on her thumbs!  However Shimano offers various other shifters.  Some only plug into STI levers for drop handlebars, so they were out.  What we settled on in the end were tri-bar end shifters, with a custom mount consisting of a wooden block and a flattened hose clip, all painted black to look a little less Heath Robinson.  They had the benefit too of being adjustable along and around the bars, so that she could operate them with fingers instead of thumbs

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