Good question. I am using Sram XX1 chains. They are chrome hardened ( only available for 11 speeds though ? ) and amazingly last as long as the cassettes and front rings so I simply ride the bike until it becomes obvious (skipping out of gears ) and change all 3 components at the same time. I have never broken one of these chains. My wife and sister in law have 10 speeds which cannot use the XX1s and have each broken their chains recently. The chain measurement tool will show almost no wear on these XX1 chains for many many KMs. I get about 5000 km on everything before I begin to notice any annoying gear popping and then when it gets too annoying I change all 3 parts (chain, front ring ,cassette ). The tools I bought to do the job have paid for themselves long ago. The most expensive is the Park tool Torque wrench . One thing I forgot to mention is that the SLX deraileur on this bike is nowhere near as smooth as the Deore XT on my hardtail and so I finally decided to upgrade it and have an XT on order now for this bike. Also the tires in the pic are Smart Sam Plus which are good but I went back to Magic Mary full knobbies. They are so great in the goo! The XT is an excellent bit of gear, so responsive and a joy to use. If anyone wants to learn do this routine work for yourself, watch the Scooteretti video on changing a Bosch front ring and also Park tool videos on changing a cassette and replacing a chain. I am not very mechanically inclined so if I can do it I promise almost anyone with a tiny bit of strength can too. I keep a drawer with those spare parts along with brake pads ,tubes and tires. You can order the Bosch front rings online at Rosebikes Germany. ( get some cheap rubber O rings at the same time). I have an assortment of front rings from 15-to 21. I use the larger sizes 18-21 works best on this bike ( it came with a 14 ) so I can go faster because all our bikes have delimiters and otherwise I run out of gears at top speed. Increasing the front ring size is no problem on Gen 2 Bosch motors. I hear it causes shut down on the newer motors?
