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Chain Slapping and Falling off
Hiya,
New to the sport and have a recurring problem. I am riding a 29er hardtail and keep dropping my chain when riding on rougher terrain, usually downhill. It slaps about pretty hard as well.
I have looked up chain guides and the like, but note that they seem to work for one or two chain ring set ups, where I have 3. Also, I was wondering whether a chain tensioner might do the trick - or both.
I would appreciate any advice anyone has on what I can do equipment or set up wise to try and minimise this.
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Hi,
regardless of wheel size, if you are dropping your chain, then it's probably because your rear derailleur is struggling to keep the chain under enough tension so that it doesn't drop off. the fact that its slapping around all over the place is evidence of this.
I am going to guess that you are probably in your small ring at the front... or the middle ring and the small ring at the back. I'm guessing the small ring at the front.
Prior to going downhill over rough stuff, try shifting to your large front ring, this puts the rear derailleur under extra tension, which reduces chain slap a heap, and nearly eliminates the chances of the chain falling off. Also, see if you are pedaling backwards at all whilst descending as this can also cause your chain to fall off.
I'm not saying this will solve your problem, but in 3-4 years of racing and riding, I have yet to drop a chain.
I'd look at chain length too. Put the chain in the big front ring and 4th from top at the back. If there is still slack in the chain, you could stand to loose a couple of links. Just don't take too many and end up with a snapped chain.
If the above suggestions don't work for you, you could try a rear derailleur with a clutch mechanism. Removes most of the chain slap. Worked wonders for me.
I had same problem on my dually. Ended up swapping the big ring for a bash ring/guard and fitting a chain guide. Hasn't come off since.
Chain length and fit a clutch derailuer. Problem solved!
I have 3 bikes and haven't dropped a chain in over 5 years!
It's been my experience with bikes at the cheaper end of the scale that for some reason the chains are usually one, sometimes two link-pairs too long.
You should have only enough chain to pass around the big ring at the front and big cog at the back and still be able to join the chain together, just. Best to look at the instructions that come with your next replacement chain.
for guidance
On my first bike I used to drop the chain continually, not even off road, until I fixed this and then - viola! - no more chain drop. This was before clutch derailleurs.
Changing to the big ring helps limit chain slap on non clutch derailleurs. This is what I do on my 3x9 bikes.
On my Scalpel 29er, which has an XTR clutch RD, I don't actually remember hearing my chain hit the stay ever, and that's in just on a year's riding. I still run a rubber chainstay protector anyway (won as a freebie at a race), but mainly for insurance purposes seeing the bike is carbon.
I bought a Bionicon Chain Guide for my Three Ring as I was getting really sick of dropping chains on trails with lots of drops ... it works very well. Read My blog article
Thanks for all the tips guys - I will certainly look at the chain length as that was my first hunch, and also the Bionicon Chain guide as I saw that and from what it says on the box should do the trick, though I've noted a lot - if not most - people comment on the apparent (lack of) value, as you did amarkie.
For those who suggest a Clutch Derailleur, any suggestions on what brand/model I should be looking at? From what I can tell neither the SRAM or Shimano offer a clutch on 9 speeds cassette, so does that mean I need to embrace the cost of new shifters and cassette too?
Chain length was my first thought also. As also mentioned, its good habit to move to the big chain ring up front for those long rough descents. Your chain will slap the chain stay(frame), so a chain stay protector is a good investment to reduce the slapping noice and protect your frame.
If problem persists, I would be look at the derailleur next. Chain guide is the last thing I would be looking for. You shouldn't need one if the chain length and derailleur are in good order.
Not a 100% certain, but I believe 10speed derailleurs will work fine on 9 speed cassettes. Just a matter of correct tension and setting the limiters.
If you are 9 speed, then the only clutch option open to you is if you have a sram 9 speed drivetrain, then a shimano shadow plus 10s will actually work - it is the only option for 9 speed.
If you don't find any problems then really it's about modifying your riding - you shouldnt be dropping chains that much. Smooth riding, taking weight off the rear whenever hitting rocks, and never pedalling backwards all help a bit. You'd be amazed how many people who drop chains, do so because as they coast and bounce through rocks they let their cranks go backwards. Riders who never drop tend to always crank forwards when needing to change the position of their pedals to avoid rocks/logs
A worn out chain-ring can cause problems too. Look up chainsuck.