I have a [Carrera Subway 2](https://www.halfords.com/bikes/hybrid-bikes/carrera-subway-2-mens-hybrid-bike-2020—black—s-m-l-xl-frames-346198.html) from Halfords that I bought 9 months ago. I only use it to get around the town where I live, and in total, I have probably done around 300 miles.
Since owning it, the hub failed and the chain was worn only after 3 months of use. When I brought the bike to the shop, they said those issues were not covered by the warranty. I bought another wheel (I wasn’t able to service the hub, and paying for the job was more expensive) and a new chain.
To my surprise, my **chain is worn again for the second time in nine months,** which makes me think there’s something wrong with the bike. I take care of the chain regularly, I avoid cross-gearing and I do not abuse the bike.
To my surprise, when I checked compatibilities of the components, I saw that the max teeth of the largest sprocket of the cassette for the rear derailleur (RD-M370) is 34 teeth, while the cassette that came with the bike is 11-36. Indeed, derailed and cassette don’t appear as compatible on the Shimano website.
**My question: could this incompatibility be the cause of the chains wearing out so quickly, or is it unlikely to be the cause? (I thought that a couple of teeth would be just fine).**
P.S. Do not buy from Halfords if you don’t want to be frustrated with poor post-sales services.
by chiarli_b