Cassette and crank advice

I am really enjoying getting back I to my boardman team 650b that I have had for 5 years due to the lockdown. I have new tryes, put on a new shimano mt ear brake and just ordered a brand ascent 2 dropper post.

My question is are the new cranks and cassettes any better than the one I have. Mine has 20 gears, 2 front and 10 back (sorry for the layman's terms). Its a FSA comet 368 42/27, SRAM x7 gearing currently and I'm looking at a SRAM nx eagle DUB 12sp Groupset - boost at around 285pound.

Is there any benefits on one front gear instead of 2? Weight benefits? A worthy upgrade or little benefit as mine works fine?



  • steve_sordy
    steve_sordy Posts: 2,441
    A typical 10-speed 2x has a gear range of 5.14. The 12-speed you are putting on has an 11-50t cassette on the back, so a gear range of 4.54. Therefore you have a 12% smaller gear range, which is on average only one gear shift smaller. So depending upon which front ring you choose, you will either find it marginally harder to get up steep hills or you will spin out on the flats sooner.

    Be sure that your current hub will take the Sram nx 12-speed cassette. Make sure that the Sram 12-speed groupset bottom bracket will fit your bike.

    The removal of the front shifter will tidy up the bar and leave room for the dropper remote that you are buying, all good!

    The main benefit of 1x is simplicity. You will very soon come to love it and will never think to go back. There may also be a weight benefit, depending upon what you buy and what you are getting rid of.

    The Sram 12-speed tooth form on the front ring is unique and is brilliant! It lasts ages and ages. You should find that the chain lasts many times longer than your 10-speed chain, and therefore your cassette will as well. You need to buy the correct offset of front ring 3mm or 6mm. I can't tell you which one to get (because I've forgotten which way round it is), but it is to do with the width of your rear axle. Someone else on here will know.

    12-speed shifting is very good, but set-up needs to be spot on to make it happen. Because of that dinner plate 50t gear, the mech arm is quite low and can catch on more stuff than you are used to. This can affect the mech arm alignment and cause odd shifting problems that your conventional adjustments cannot fix. If that happens it will be a misaligned mech (usually a bent mech hanger). After three visits to the bike shop for mech hanger alignment at £10 per go, I bought the same tool they use and made my own adjustment. I took the time to make it bang on instead of within 3mm and I had no further trouble. Make sure that your groupset comes with the orange plastic template to help you set the B gap. The B gap for 12-speed is more like 15mm not the 3mm or so of conventional gearing. That size of B gap ensures that the mech can effectively deliver the chain onto the 50t gear.

    Is 12-speed a worthy upgrade vs 2x10? Yes I believe so. I had a YT Capra with 2x10 and I bought a Whyte T130 with 1x12. Both had a dropper and remote. Once I had experienced the 1x12, I soon converted the 2x10 to 1x12. There was no way that I wanted the 2x10 back!

    I fitted the GX to the Capra and in total I saved 393gm in weight. I saw a video shortly after I did the change that said the NX shifting performance is the same, but the feel is slightly different, looser and more flexible than its more expensive brothers. That may be considered a good or a bad thing, it depends upon your taste.
  • wavey1000
    wavey1000 Posts: 59
    Wow great info thanks for that. If I upgrade I guess I'll get advice on sizes etc from the bike shop and ask them to fit to ensure its bob on. Thank you for taking the time to reply
  • wavey1000
    wavey1000 Posts: 59
    How do I check my current hub will fit the 12 speed?
  • steve_sordy
    steve_sordy Posts: 2,441
    It might fit the current hub because the smallest gear on your NX cassette is 11t. It was the need for a 10t gear that drove Sram to produce the XD hub (smaller diameter).

    Someone on here will know for sure if the website you are buying the NX from can't tell you, alternatively contact the SRAM technical centre and ask them.
    0843 487 8815