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Hi All,
Having major issues with my NX Eagle drive on a Trek Roscoe 8 2020. It’s been back to the shop where I bought it 3 times now plus another Trek dealer but no one can fix/diagnose the problem. When I put some power into the crank in the smallest gear on the cassette it feels like it’s slipping a tooth. It’s very intermittent and only does it when your putting the power down. You’ll get a jolt and a bang and then it’s fine. It’s usually worse when your going up a bit of a hill, and doesn’t seem to do it in any other gear. As I said it’s been inspected several times now and no one can see anything wrong with it, plus it doesn’t really do it when they have it for a test. I’ve been told by one shop that due to the nature of the 1x system that it will slip as there isn’t enough wrap of chain around that gear. The other shop says that’s rubbish. I’ve also been in contact with Sramtech in the UK and they say that’s rubbish too. I have finally got the cassette and the chain replaced under warranty, but tried the bike again today and it’s just as bad, if not worse. I’m starting to pull my hair out over it, and get the feeling the shop I bought it from doesn’t really believe me. Any help or advice would be greatly appreciated, as I don’t know what to do next!
Thanks,
Steve
Free hub slipping?
How old / worn is the chainring? You can get those sort of symptoms with chain suck when it 'releases'..
I have been thinking about it all afternoon and I wondered if it could be the free hub. There was a known issue with some of them turning to mush, but neither shop had mentioned it, so I don’t know. The bike is less than a year old, and I’ve probably only done 100 miles on it.
Without seeing it I'd go with the freehub pawl not engaging properly and then BANGing into the next position as mentioned above. 'Sram' / Formula hubs are bad for this for example and the pawls ending up rounding off and even snapping in half.
Freehub. I've had it. It's only randomly not hookong up properly. Pull it open, check springs etc on the paws or look for damage.
I have this with issue on the smallest gear but for me it looks like the gear is buckled when I spin it at low speed this is on a NX cassette. Maybe worth a look and this has happened on 2 different wheels using the same cassette.
I had exactly this issue with my 2020 Roscoe 7. My LBS fixed it with a new derailleur. Apparently its a common issue on the NX stuff. Something to do with the springs not keeping tension correctly, and trying to throw the chain into the stay. Eitherway, had no issues since the new derailleur went on 8 months ago
NX has a known problem with pivot binding due to the soft nature of the metal used, so it's probably that but also Trek has had a lot of issues with the freehubs on the marlin/roscoe wheelset. Surprised the original shop hasn't had loads go through warranty, I know my local shop has.
Try a different wheel/mech l in there if you can to be 100% sure, I'd have thought one of the shops you've taken it to would have done this for elimination purposes as that's what I used to do in this situation when I worked on the spanners for the LBS
Mate has a Roscoe 7 with SX Eagle, low spec bikes with shoddy 12 speed is stupid, just get 10/11 speed deore on there and put some actual useable forks or hubs on instead..
When he starts getting issues he’ll be getting some 11 speed kit fitted by me
Thanks for all the replies. So it’s either the mech or the free hub, neither of which has been mentioned as a possible cause. If it is the free hub, then is there any reason why it only slips in the 1 gear?
Not looking forward to taking it back really as it’s been a struggle to get this far! Most of the time I’m being told either there is nothing wrong or what do you expect, it will slip if you ride it like that. All Trek dealers know about the issues with the free hub so surprised they haven’t thought of checking that.
Mine used to slip when i was applying force on climbs as i got out the saddle. Even led to an OTB the once, but like i said, since the derailleur was replaced its been trouble free since. The guy at the Trek dealer i use knew straight away when i spoke to him on the phone. Said 'yeh usual story with those, i'l get a mech oredered today' and not to bring it in for a week or so as the parts were scarce then! Thank god it went back then and not recently
Got my bike back and it now has a new back wheel fitted. It looks like there was an issue with the hub. A good test over the next few days will hopefully confirm if it’s been fixed
Had some issues with shifting on NX Eagle, and much improved after faffing w B-screw gap, seems NX v sensitive to that. But ultimately after the nx derailleur ate itself I put on a 12speed slx, and no issues or chain tantrums since