Di2 destruction

While out riding my Ultegra 10-speed Di2-equipped road bike, the rear derailleur sheared itself from the frame dropout and lodged itself in the rear wheel. On inspecting it, Madison (the UK distributor for Shimano) declared that this was not due to defective manufacture.
As Shimano have stopped making Di2 10-speed derailleurs, I have had to spend £525 on an 11-speed drivetrain (rear derailleur, front derailleur, chain and cassette).

I didn’t replace the 10-speed crankset with an 11-speed one, so not all 22 gears engage as well as they should. I appear to have reached an impasse with Madison. Any suggestions?

Chris Wagstaff

A It is impossible to offer much advice on the reason for the rear mech’s demise without having seen it working prior to the incident. Was it regularly serviced by a competent mechanic? Were you pedalling hard and trying to change gear at the time? Was the damage caused by the mech moving into the spokes? Although shifting is controlled electronically, there are ‘stopper’ screws that prevent the mech over-shifting past the end sprockets. If the low gear stopper screw was correctly adjusted, it is hard to see how the derailleur could do this, which may explain Madison’s decision.

I assume you bought 11-speed dual-control shifters? Perhaps the best course of action would be to sell your surplus 10-speed components and use the proceeds to fund the purchase of an 11-speed chainset to complete your groupset and allow you to fully enjoy the delights of electronic shifting.

Richard Hallett

​​Cycle’s Technical Editor

This Q&A was published in 'Cycle' the magazine for members of Cycling UK. To contact the experts, email your technical, health, legal or policy questions to editor@cyclinguk.org or write to Cycle Q&A, PO Box 313, Scarborough, YO12 6WZ

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