[Pasta4lnch]

Hey all...newb to bike repair here - having an odd issue with my drive train. 2020 Growler Amer Stout fat bike w GX drive train. Certain gears start slipping and changing all of a sudden. Where it gets odd is when I'm coasting, the normal clicking of my hub sounds more like grinding (somethings definitely rubbing somewhere). I can also hear the chain finding a hard time seating and is clicking too in certain gears. I can't replicate any of this with me off the bike so its been hard to pinpoint where/what the issues is with exception of the chain clicking, but there are no visible causes. I regularly lube my chain and there is no visible debris stuck anywhere. Any thoughts?

Edit - I should also mention I'm a really heavy rider 350lbs. On my second bottom bracket since I got the bike in last October - ride 1-3 times per week 4-10 miles single track mostly.

 

[cdalemaniac]

-Check if rear wheel axle is cracked, allowing your freewheel body to flop around.
-Check freewheel pawls and freewheel bearing as well since grinding while coasting is indicative for bad pawls/springs.


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[p0is0n0ak]

-Check if rear wheel axle is cracked, allowing your freewheel body to flop around.
-Check freewheel pawls and freewheel bearing as well since grinding while coasting is indicative for bad pawls/springs.


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^^ This. Heavier riders and stock/ OEM hub sets don't mix very well. At 250 lbs, I shattered 2 pawls and cracked the axle on my stock hubs while I was saving up for my i9s. Keep riding and you'll lose the weight, but to keep you rolling, you'll likely need to replace the rear wheel with something that has a steel axle. There are a few threads knocking around here discussing this. Try the Clydesdale sub-forum.

 

[biker human]

Hey all...newb to bike repair here - having an odd issue with my drive train. 2020 Growler Amer Stout fat bike w GX drive train. Certain gears start slipping and changing all of a sudden. Where it gets odd is when I'm coasting, the normal clicking of my hub sounds more like grinding (somethings definitely rubbing somewhere). I can also hear the chain finding a hard time seating and is clicking too in certain gears. I can't replicate any of this with me off the bike so its been hard to pinpoint where/what the issues is with exception of the chain clicking, but there are no visible causes. I regularly lube my chain and there is no visible debris stuck anywhere. Any thoughts?

Edit - I should also mention I'm a really heavy rider 350lbs. On my second bottom bracket since I got the bike in last October - ride 1-3 times per week 4-10 miles single track mostly.

If you don't know how already youtube how to tune a derailleur, and make sure your derailleur is in tune. You can also try taking a link out of your chain.

 

[bingemtbr]

Take your bike into your LBS.

Might be something simple, like the freehub body is dirty/gummed up and needs TLC. Or it could be something complex, like the freehub body is dirty/gummed up and needs to be rebuilt or replaced. Have the LBS mechanic accompany you on a test ride to allow you to properly illustrate the issue.

 

[11053]

This sounds like a 12speed GX Eagle set up issue, but the wild card is the grinding while coasting that you mention.
If the hub bearings and freehub are OK, then derailluer adjustment is usually easy.
Highly likely derailluer high/low limits, cable tension and B screw tension need adjustment or else your derailluer mounting bolt is backing out.
Causes could be bent derailluer hanger, B tension not to spec, cable tension off or the derailluer mounting bolt is backing out.
However, if derailluer is in spec, then the hub is likely the culprit.

 

[Taroroot]

Take wheel out of frame and itll become obvious if axle is broken. I did that a few times in the freewheel age, and i was a flyweight around 115 lbs! But thus was under trials use, hucking drops to flat concrete. Also try grabbing wheel at tire and see if theres side to side play.
You can eyeball derailleur hanger alignment and get it fairly good.

 

[Pasta4lnch]

This sounds like a 12speed GX Eagle set up issue, but the wild card is the grinding while coasting that you mention.

The weird thing is, the grinding isn't constant. Only in certain gears. The hub appears fine - though I will take the advice of taking the rear wheel off and checking that.

I will also take biker human's advice and learn a bit about tuning my derailleur...

Thanks for the advice all!!

 

[Pasta4lnch]

I took it to my LBS. They said the derailleur seems spread apart a bit and the bit that holds it on the bike is slightly bent...honestly if this is all true, it has to be by the slightest amount because I couldn't tell... but they were going to assess and let me know. Thanks for all the replies!!

 

[Pasta4lnch]

Also turns out my axle was broke too...oy! Ima big guy - I suppose this is to be expected...