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Adjust your bike to keep your chain in place

Unshipping your chain can be annoying at best, sometimes dangerous, especially if it happens when you’re in traffic, so you need to minimise the chances of it happening by setting up your bike right.

If your chain has started to come off frequently when it didn’t in the past, something in your bike setup has changed. The first thing to do is check that all of your drivetrain bolts are tight, that nothing has moved or got whacked, and to make sure your rear wheel is correctly seated in the dropouts.

Let's take a look at how you deal with other possible reasons your chain is coming off.

If your chain comes off at the front

Adjusting your front derailleur limit screws
Dropping chain front mech H and L screws - 1.jpg

Dropping chain front mech H and L screws - 1.jpg

If your chain is coming off the chainset, make sure that the two limit screws on your front derailleur are properly adjusted.

Dropping chain front mech 2 screws - 1 (1).jpg

Dropping chain front mech 2 screws - 1 (1).jpg

One of the screws – sometimes, but not always, marked H for ‘high’ – limits movement of the front derailleur cage outwards. 

The other screw – sometimes, but not always, marked L for ‘low’ – limits movement of the front derailleur cage inwards.

Dropping chain front mech L screw - 1.jpg

Dropping chain front mech L screw - 1.jpg

If your chain regularly comes off the inside of your chainset, it could be that the L screw needs adjusting. Put the chain on the small chainring and the largest sprocket at the back. The inner plate of the front derailleur cage should nearly but not quite touch the chain; we’re talking about a gap of 1-2mm. If the gap is larger than that, turn the L screw clockwise to move the inner plate of the front derailleur cage closer to the chain.

Dropping chain front mech H screw - 1.jpg

Dropping chain front mech H screw - 1.jpg

If your chain frequently comes off the outside of your chainset, it could be that your front derailleur H screw needs adjusting. Put the chain on the big chainring (up front) and the smallest sprocket (at the back). The outside plate of the front derailleur cage shouldn’t quite touch the chain. If there’s a gap larger than 1-2mm, turn the H screw clockwise and you’ll see the cage move inwards. 

>>Read more: How to adjust front derailleur indexing 

Other solutions

You can still occasionally unship your chain even if the limit screws are set correctly, particularly if you change gear under load (while standing or pushing hard on the pedals). Try backing off your effort (but still pedaling) when shifting between chainrings.

Another way to keep the chain from coming off the inside of the chainset is to use a chain catcher.

Raleigh Maverick Comp - SRAM Rival Chain Catcher

Raleigh Maverick Comp - SRAM Rival Chain Catcher

A chain catcher is essentially an arm that acts as a barrier to the chain overshifting inwards. SRAM Red, Force 22 and Rival 22 front derailleurs have an integrated chain catcher.

Trek Ion CX Pro - chain catcher

Trek Ion CX Pro - chain catcher

If your bike doesn’t already have one, you can fit a chain catcher retrospectively. There are different designs out there and they’re all pretty easy to install.

>> Read more: The rise of the chain catcher (no, really!) 

If your chain comes off at the rear

Adjusting your rear derailleur limit screws

If your chain is coming off at the rear, it’s often a simple matter of adjusting the limit screws on your rear derailleur.

Dropping chain rear mech L screw - 1.jpg

Dropping chain rear mech L screw - 1.jpg

If the chain is coming off the inside of the cassette, put the chain onto the smaller chainring (at the front) and the largest sprocket (at the rear). Then turn the L screw clockwise until you see the rear derailleur cage (the section that hangs down) start to move away from the centre of the bike. You need to move it to the point where the chain can move freely into the largest sprocket, but can go no further than that.

Dropping chain rear mech H screw - 1.jpg

Dropping chain rear mech H screw - 1.jpg

If your chain is coming off the outside of the cassette, put the chain onto the larger chainring and the smallest rear sprocket. Then turn the H screw clockwise until you see the rear derailleur cage start to move towards the centre of the bike. You need to move it to the point where the chain can move freely into the smallest sprocket, but can go no further than that.

Dropping chain wheel in chainstays - 1 (1).jpg

Dropping chain wheel in chainstays - 1 (1).jpg

Again, though, if the chain wasn’t coming off before but has recently developed the habit, the setup has somehow changed. Before you do anything, check that the rear wheel is sitting correctly in the dropouts with the rim running centrally in the chainstays, and make sure that the rear derailleur and its hanger (the piece to which the rear derailleur is bolted) aren’t bent. In most cases, the rear derailleur pulleys should be lined up directly underneath one another. 

>>Read more: How to adjust and tune indexed rear derailleurs 

What if your chain is still coming off?

If you do all this and your chain is still coming off, there are several other things to look at:

• Your front derailleur could have moved. Check that it is positioned correctly by taking a look at our article on how to index front gears.

• Is your drivetrain worn and in need of replacement? Shifting performance can start to become less smooth and more erratic as components near the end of their useful lives. 

• It might be that the chain is worn, has a stiff or bent link, or has become clogged up with dirt. A visual inspection while turning the cranks should reveal if there’s a problem here.

• The chainring, or a chainring tooth, could be bent. Again, a visual check will tell you what you need to know.

Dropping chain big to big - 1.jpg

Dropping chain big to big - 1.jpg

• It could be that you’re running the chain at too extreme an angle – in the larger chainring and the largest sprocket (as in the picture above), or the smaller chainring and the smallest sprocket. Some systems can handle this (even though it's not a particularly efficient way to ride), some can’t.

• Your chain could be too long or too short. Before putting a chain on, thread it onto the larger chainring and the largest sprocket but don’t run it though the rear derailleur. Pull the two ends together and add one complete link (one inner and one outer half link) to get the correct chain length.

• You’re running a chain that’s not compatible with the rest of your drivetrain, in which case you need to change it.

There are other reasons why your chain could come off, but we think these are the main ones. If you think there’s an important cause we’ve missed, tell us about it down below.

 

Mat has worked for loads of bike magazines over 20+ years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for eight years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.

14 comments

Avatar
dafyddp [464 posts] 2 years ago
2 likes

Good read.

Would just add... if your chain regularly comes off/grinds/crunches on the hills it may well be poor technique - definately so in my case. Don't try changing down when you're out of the saddle, especially if on some 15% killer - this places enormous stress on the whole chain drive.  Anticipate in advance (while still seated) and aim for a smooth transition through the gears.

Avatar
NoOneSpecial [14 posts] 2 years ago
3 likes

Seriously?!!! Is this 'article' a piss take?

FFS, you forgot to mention.......

1) F/mech height.

2) F/mech angle.

3) Play in cranks/worn B/B.

4) Ten ton of shite from the back tyre clogging up the pivot bushings.

5) Worn out chainrings.

6) No idea what the 'trim' function is on Shimano STI.

7) Problems with Shimano 10 speed cable issues under bartape.

8) Shimano's pain in the arse f/mech cable angle setup.

9) Internal gear routing.

10) Ten ton of crap inside the STI/Ergo/Double-Tap shifters.

11) Bike bought in a box and put together by an idiot who plays around with a screwdriver.

12) Bent hanger obviously.

13) Riding like a twat as you are overweight and have too much money and have no idea about gears. But hey, a 6K bike is fashion.

Do I need to go on.........

Please do not publish crap advice for Joe Public. Plugs are fitted to all electrical goods these days, in the days they weren't.......

But hey, what do I know,

NoOneSpecial.

Avatar
flobble [141 posts] 2 years ago
11 likes
NoOneSpecial wrote:

Seriously?!!! Is this 'article' a piss take?

FFS, you forgot to mention.......

1) F/mech height.

2) F/mech angle.

3) Play in cranks/worn B/B.

4) Ten ton of shite from the back tyre clogging up the pivot bushings.

5) Worn out chainrings.

6) No idea what the 'trim' function is on Shimano STI.

7) Problems with Shimano 10 speed cable issues under bartape.

8) Shimano's pain in the arse f/mech cable angle setup.

9) Internal gear routing.

10) Ten ton of crap inside the STI/Ergo/Double-Tap shifters.

11) Bike bought in a box and put together by an idiot who plays around with a screwdriver.

12) Bent hanger obviously.

13) Riding like a twat as you are overweight and have too much money and have no idea about gears. But hey, a 6K bike is fashion.

Do I need to go on.........

Please do not publish crap advice for Joe Public. Plugs are fitted to all electrical goods these days, in the days they weren't.......

But hey, what do I know,

NoOneSpecial.

All useful considerations (if a bit impolite).

Other than 13 onwards. Which is just bigotry. Shame.

Avatar
monkeytrousers [133 posts] 2 years ago
1 like

[/quote]

All useful considerations (if a bit impolite).

Other than 13 onwards. Which is just bigotry. Shame.

[/quote]

Although you may say the same about BMW drivers. Is that bigotry as well?

Avatar
mike the bike [1098 posts] 2 years ago
1 like

My father, never a man to be troubled by his deficiencies, would often say that bigotry was just another word for experience.  When I was twenty I thought he was a reactionary old goat; many years later I see that he indeed had a point.

Avatar
PATMAC [26 posts] 2 years ago
1 like

+ 1 on ALL NoOneSpecials list.. a caveat to 13 however, they are not all overweight, But they think in BM terms..and equate expensive machines as the  fast way to speed, forgetting that most of the newbie or pilgrims as i call them still have 1.1 engines, and most of all..   when i worked with BM's they were advertised as drivers cars, ime 95% of their owners or drivers couldn't drive a nail into a bar of soap..but as someone who works with race bikes for clubmen and poseurs everything on the list is dead right, the ones i love the most are the new teck heads who google probs go and watch a Utube video and never having had a tool in their hand ever.... instantly know all about setting up race bikes..  on the stand a machine may work perfectly when there isn't any weight or load on the frame or chain ..whole different scene out on the road sometimes..  

Avatar
CXR94Di2 [2202 posts] 2 years ago
1 like

Get a Shadow plus clutch rear derailleur 

Avatar
TypeVertigo [428 posts] 2 years ago
1 like

Somewhat related: Your rear derailleur might need an overhaul.

Lately I've had odd chain slippage problems because the P-knuckle spring on my 105 5700 GS (medium cage) rear derailleur isn't keeping chain tension as well as it should, especially when using smaller cogs with the small ring. This sudden chain slackness and "sliding" can feel like chain drop but isn't quite as catastrophic...it does interrupt the predictability of your power transfer to the rear wheel though.

One temporary fix is to tighten the B-tension screw more to force the cage away from your cassette and increase chain tension. The other is to disassemble the rear derailleur cage and P-knuckle spring, clean it out, and then realign the relevant pins on the spring with the holes on the P-knuckle before reapplying grease and reassembly. On 105 derailleurs there is a second pin hole for the P-knuckle spring that will yield even more spring tension on the cage when used.

https://www.youtube.com/watch?v=1sZS49JmXK0

Avatar
JonD [496 posts] 2 years ago
5 likes
mike the bike wrote:

My father, never a man to be troubled by his deficiencies, would often say that bigotry was just another word for experience.  When I was twenty I thought he was a reactionary old goat; many years later I see that he indeed had a point.

 

Oh, I dunno, if anything I'd suggest that bigots are lacking the experience to become well-rounded individuals from the ones I've encountered...

Avatar
Roadie_john [85 posts] 2 years ago
1 like

Go fixed. As long as the wheelnuts are tight, the chain tension and chainline are fine, you'll never unship the chain again. Ever. 

 

 

Avatar
Nzlucas [128 posts] 2 years ago
3 likes

How about: 

Take it to your local bike shop and get it checked over!

 

Sure fire way to wreck your bike is to muck with limit screws when you don't know what you are doing. What if your hanger is bent and you adjust the rear dearalier inwards - bam - into the wheel and a new wheel, mech, hanger and chain. 

 

Disclaimer: I work in a bike shop. we warn people off playing with limit screws. 

Avatar
ajd [66 posts] 2 years ago
1 like
Roadie_john wrote:

Go fixed. As long as the wheelnuts are tight, the chain tension and chainline are fine, you'll never unship the chain again. Ever. 

 

You are right but if you are lazy and the chain is a bit slack because of stretch, it can fly off if you are spinning at 130+rpm. Done it twice and felt stupid both times.

Avatar
Roadie_john [85 posts] 1 year ago
0 likes
ajd wrote:
Roadie_john wrote:

Go fixed. As long as the wheelnuts are tight, the chain tension and chainline are fine, you'll never unship the chain again. Ever. 

 

You are right but if you are lazy and the chain is a bit slack because of stretch, it can fly off if you are spinning at 130+rpm. Done it twice and felt stupid both times.

yeah. I got the chainline wrong once and broke the chain at 30mph plus. That was *interesting*. And I had a chain that said 1/8" on the box but appears not to have been. It unshipped on the fast downhill just out of my street. Stayed upright both times but became beyond anally retentive about chain line, tension and fit...

Avatar
The _Kaner [1172 posts] 1 year ago
0 likes

How can I stop my chain coming off?

Stop yanking it!