Ok, I haven't had a broken chain yet, but since I commute to work, I want to be prepared and knowledgeable in case it does. I have a chain repair tool already, and I think I understand how it works...Here's what I'd like input on:

1. Do I need to carry an extra pin, or link, or anything, or can I simply remove the broken parts, and connect two non-broken links on the road.

2. If I do this and remove a link, the chain will obviously be shorter, but the tension in the rear derailleur will make up for this to get me home, right?

3. If I do this, and get home on the shorter chain, do I need to go get a new chain of proper length as soon as possible, or is a shorter chain no big deal?

thanks!
-Andy

I just remove the broken parts and reconnect the chain. A slightly shorter chain will allow you to finish your ride and get you home. You can replace it later.
Right!
I'd replace it. If a chain gets to the point where it's breaking spontaneously, it's time to spend the, what, $10-30 it costs to buy a new one.

First of all, chain breakage on the road is relatively rare and unnecessary. Most chain breakage is the result of a chain not being closed properly in the first place, or the result of hard shifting under load which can push the plates outward beyond the end of the pin.

If you're riding a 8s or more system, you can't close the chain with your chain tool, so the best answer is to carry a connecter link. If you're chain breaks, use the tool to remove the rest of the outer link at the break leaving you two inner link ends which you join with the connector. The spliced chain is still the original length.

On the off chance you have to actually shorten the chain, the answer to your last question depends on how much downside room you left yourself originally. If you measured by the big/big +1" method, your chain started out at the minimum length, and you need to restore it to that length ASAP if not sooner.

Chain breakage is no big deal if you carry a chain tool and a quick link. Simply push out the broken link and replace with the quick link. Most bike multi tools have a pin pusher.

I carry the cut-off links from shortening the chain initially along with a couple of master links and a chain tool. In this way I can remove any damaged links and splice in a few links to replace them. This saves me from running a too-short chain and causing damage due to a forgetful shift, and from having to remember to go back and fix it later

Put a pair of nitrile rubber gloves in your seat bag/repair kit.
Nothing is worse than having to do a roadside repair and then having dirty hands to mess up your bar tape/grips.

What? I've repaired my 8-speed on the road without a connector link using a multi-tool based chain tool a few times, so I don't understand this statement. Did I do something wrong?

Parallel to this thread is the choice of chain length. To remove a damaged link and reassemble the chain with a connecting link (carried in your tool kit) is pretty straight forward. But if the chain started out being as short as possible, which seems to be the advice many give, the now repaired chain will possibly be so short that the big/big cog combo could be damaging to your ders or hanger.

While I agree that chain breakage is very uncommon these days it is pretty much the end of your ride if it did happen. On a commuting bike you'd better have a phone with you to call the boss... and a friend to pick you up.

I choose to set my chain lengths as long as will work well. This way when you do have to repair the chain you're still able to shift through all your gears w/o damage. Of course you could always pack two connecting links and a stretch of chain to splice in the amount that got removed. Andy.

It can break...

Probably, and it may cause you to need to do a roadside repair again in the future. Hyperglide shifting, by any other name, makes it possible to shift under load. This puts side stress on side plates forcing them outward on the pins. At the same time, in an effort to make chains narrower, the pins no longer protrude beyond the ends of the plates, leaving no margin for spreading.

So all chains produced since the Hyperglide era (8s and newer) have the ends of the pins peened over the plates like rivets. When you push these through , you break off the overhang, leaving a plain end which won't resist side forces. Shift badly and the plate will move out and hang half on/half off. It may not break right then because there's still some strength, but load it enough when climbing hill, and the plate will let go, and the chain snap.

Whether your chain breaks sooner or later, or never depends mostly on how you shift combined with luck, since it only matters if the shift force is applied to that one joint. So it's about a one in a hundred chance for each bad shift, but keep it up and your luck will run out.

BTW- most people never break chains, but it can happen to anybody. However if you break more than one chain in a lifetime it's probably not just bad luck.

OK, I buy that. I thought by the way you said it was that the repair could not be done without a spare pin in your bag. As you say, chains break infrequently enough that carrying spares for that eventuality is pretty pointless. My feeling on this is, when it happens, repair the chain using a chain tool, finish your ride, go home and then replace the chain, hence removing any long term issues you might have with a poorly repaired HG chain!

EDIT: I have to laugh at the idea of carrying latex gloves with you at all times!

I had a brain fart a couple years ago and lengthened my 9 speed chain by just reusing a pin.
I don't mash, so I was OK.
I temporarily loaned my bike to an acquaintance while I was working on his.
He got about 6 blocks, broke the chain and turned my RDER into a pretzel.

I guess I should have said that you can't properly close a chain with a chain tool. In any case, if you're going to bother carrying a chain tool, the added weight of a connector is insignificant. IMO either carry both or neither.

I'd agree with that. To me once a chain breaks, it's destined for the trash anyway. Its not like new chains are expensive. As for the chain tool, well I have one on my multitool. To carry a connector around with me isn't really a weight issue, it's just likely that I'd lose it before I got to use it!

The latest Derailleur chains you should save the pieces removed to shorten the chain when it was replaced , and a few quick Links.

older chain designs where the pins did not have to be so short as to be flush with the outer side plate,

could be repaired with a spare are link of same chain or shortened , with the chain tool ..

No longer after the push to pack in more speeds in a limited cassette driver space ..

How many 'Speeds' you packin?

+1 on quick connectors and gloves

also never broke a chain on the road but a few times a year on trails mt biking

I carry an old master link and chain tool.....Chain breaks,pop off outer side plates,install master,continue riding...You shouldn't be shifting into big-big even with a new chain.

Chain failure is pretty common on MTB. Strong rider, shifting under load or racing...
I broke 3 or 4 Shimano chains on MTB while going on a steep uphill. I always refuse to walk my bike lol
Never broke a chain on a road or on a hybrid bike, but I know few who did that.

I always carry quick links and a chain tool.

1. Sounds like I'm probably ok with just the chain tool on my multitool...even if carrying a spare link or connected might make the job easier, since I would only riding the bike less than 10 miles on the repaired chain...i can avoid the big ring that long.

2. I have not altered my chain length at all other than infrequent Lube...it came with the bike...I assumed it was the right length.

3. I am running 21 speeds (3&7) on a hybrid. I rarely use the big ring anyway.

4. I wont be carrying gloves with me other than cycling gloves (or in the current season, realm warm non-cycling gloves...thats why I wear black shorts/pants...to wipe my hands on.

Well, the master links are cheap and I will use them anyway and the cutoff links are already paid for, so there is no incremental expense. I'll gladly cart around the extra 25g (with chain tool) since I ride for exercise anyway. I have only had one chain break but i have helped others with my spares. Worth it to me, YMMV.

+1 I find the gloves a little tricky to neatly pack away but they're totally necessary!

Or, another reason to stay with Black Bar tape ..

Replacement after breakage is generally not necessary, unless the chain was near the end of its life anyways. Damage leading to a broken chain is almost always localized to one link, and once that link is removed, the chain is perfect again.

8+ speed chains are riveted rather than pinned, and when a rivet comes out -- either accidentally on the road or pushed out by your chain tool -- the flange on the end of the rivet is broken and will no longer hold reliably. As you note, such repairs do not necessarily fail immediately, but they virtually ensure an eventual failure at the link. If you use your chain tool to emergently repair a chain on the road, take it easy until you get home and then replace the chain as soon as possible.

And black shorts...