A deceptively complex job, the Trek 1120 is an interesting bike, built with 29″ fat tyres for off-road touring with custom racks. As standard it has derailleur gearing, this was a conversion to Rohloff hub gearing, and adding a Gates belt drive and SON dynamo hub to power lights and a Plug5 charging device. This needed a custom Rohloff A12 hub, custom-machined dropouts, a custom-machined chainset and very careful choice of parts.
A few people have asked about doing this – total cost for the conversion was £2495, for the Rohloff, belt drive and the SON. I could send you a Rohloff conversion kit, but I would need you to send me your original left hand dropout to modify – the Rohloff conversion on its own would be £1495. Belt drive would add £395, but there’s a disclaimer about that – the belt on this bike runs VERY close to the chainstay, it’s possible it might not work on a different Trek 1120.
