Is this normal? I pedal a mountain bike on pavement. I replaced the chain with a sram pc850 and a Shimano cs-hg51-8 on 15 July. I was cleared to ride at the end of July. Now my chain and cassette is super worn. So under 5 months. The entire bike gets 2 washes/degreased every week, every link individually lubed (tri-flow). Cranking out about 30-40 miles everyday. No matter what what components I use I am having to replace the cassette and chain every 5 months or so. Is anyone else experiencing this? Thanks in advance. Cheers!