[dirtyBob]

I've owned a lot of bikes in more than 30 years of riding, and I've never had this issue. Every time I go off the lip of a jump about a half second later in mid-air I hear a clunk and feel it. It's a pattern on jump trails. Jump clunk jump clunk. It feels like the derailleur and or the chain or the culprits. It has thrown the chain a couple of times but doesn't do it often. It's a 2018 gorilla Gravity and I'm riding a GX SRAM derailleur. If I take two more links out of the chain it will be too short in the lowest gear. Anybody had this happen to them and know the fix or even where it's coming from? Why it happens? Thanks in advance for any help or recommendations.

 

[Loll]

GX has tension clutch. For the sake of isolating problem, why dont you go ahead and shorten the chain two links to see if you can rule that out.

Clunk sounds like suspension or shock top out more than chain slapping.

Can you film a video and let us hear the sound?

 

[dirtyBob]

It's not the suspension. It's the drivetrain. I feel it in my pedals when it clunks. And I work on everything on my bike outside of building Wheels. And I wrote in my original post that I can't take out two links because it will be too short to reach the highest gear and then I'll have to throw out the chain and buy another one. Thank you though.

 

[plummet]

Its possible the derraillieur banging on the frame but unlikely on in the air.

My call is its suspension top out noise transferring through the frame giving the illusion of drive train.

PS generally the drive train will rattle when rattling down tech. Not midway though a jump in the air.

 

[dirtyBob]

Thanks for the reply. It's not rattling. It's one, solid, predictable "thunk" that I feel through my feet about a half second after leaving the lip of a jump, as if all the slack in the chain grew taut immediately, and then it's gone. back to normal chain slapping.

 

[kustomz]

And that's why I ride singlespeed

 

[NJTransplant]

sounds like the clutch possibly being shot on the der? Had that happen and it would swing forward too easily and I was detecting it snapping back. New der fixed my issue, clutches don't last long with heavy abuse from my experience (although the jury is out on the sram 90 drivetrain I'm using on one bike now). Suspension compresses a bit on take off and goes back to slack mid air.

You seem sure it's not suspension top-out but it really does sound like that's the case by what you describe. I was riding a 2018 GG up until last year 🤘

 

[Nat]

How about removing the chain and derailleur for a jump run to see if the clunk is still there?

 

[Loll]

Taking two links out doesn’t equate to new chain. Put a quick link on and good as new. Is it worth it to rule out one possibility? Is your call of course. Ride on the other gears temporarily while the chain is short. Is just part of the process. As other implied, you are at a point of making sacrifices to rule out potential issues.

I am all for taking out the chain and derailleur and do a chainless run on the jump line. This rules out the potential issues further.

Otherwise this conversation will not really go anywhere further in shutting up our mouths. 😀

 

[RickBullottaPA]

Thanks for the reply. It's not rattling. It's one, solid, predictable "thunk" that I feel through my feet about a half second after leaving the lip of a jump, as if all the slack in the chain grew taut immediately, and then it's gone. back to normal chain slapping.

Which is exactly what it likely is. Maybe slow rebound down a couple clicks? Tradeoff is that it won't be as "poppy" on jumps.

 

[yzedf]

Almost guaranteed it’s a worn out clutch on the derailleur

 

[RickBullottaPA]

Almost guaranteed it’s a worn out clutch on the derailleur

SRAM clutches are relatively low spring force anyway. Different than Shimano. My guess is that rebound is set fairly quick for jumping/park riding.

 

[slimat99]

Sounds like the clutch to me. Not sure about newer sram mechs but on their 11 speeds you can tighten the clutch with an 8mm or torx bit. Use a pry tool to remove the plastic plug and you'll see how you can tighten the clutch.

To a certain extent 1x has always been noisy for me regardless of the bike. The clutch can only do so much to manage chain slap. Some frames produce more noise than others. STFU, or just a better chain stay protector might help.

 

[dirtyBob]

Thanks much for the replies. I'll give the chainless no derailer jump run a try, and tightening the derailleur too. Most appreciated.

 

[idividebyzero]

If its a pinging thunk that sounds like your rim hit a rock or metal on metal then it's a low engagement hub clunking into engagement as the chain tightens. Low engagement hubs on bikes with a lot of pedal kickback are especially annoying because they can violently clunk and stiffen up the suspension at totally random times.

 

[Harold]

If its a pinging thunk that sounds like your rim hit a rock or metal on metal then it's a low engagement hub clunking into engagement as the chain tightens. Low engagement hubs on bikes with a lot of pedal kickback are especially annoying because they can violently clunk and stiffen up the suspension at totally random times.

I was definitely thinking that it would be worth checking to see if pedal kickback might be at least part of the issue.

 

[davez26]

Thanks much for the replies. I'll give the chainless no derailer jump run a try, and tightening the derailleur too. Most appreciated.

If chainless is difficult, you could wrap a tube or other insulating material around chainstay, ride, and see if noise changes/ceases.

 

[kustomz]

All of my bikes have this. Amazon.com : CYSKY 2 Pcs Bike Chain Guard Silicone Stickers, Bicycle Frame Chainstay Protector, 3M Glue Backing Sticky Well, Durable, Lightweight (Regular style) : Sports & Outdoors

 

[dirtyBob]

It's not chain slap. But thanks.

 

[kustomz]

I had a YT Izzo that clunked with every hard edged compression, so I hung all of the components on a Ti hardtail and sold the YT frame. Never had good luck with full suspension frames.