Measuring new chain
 

Just a question on replacing my chain- this is my first time. Can I just layout my old chain and cut the new one to the same length? I just thought this would be the easiest and fastest way to do the job. I've measured the stretch in my old chain and it is between 0.75 and 1%. Thanks for the help.

Same # of links is just fine. Hopefully the new chain is just a tad shorter than the worn one.

Don't forget that when you change the chain, you should also, to prevent skipping, change the cassette/freewheel.

Really?

I always thought that if you changed your chain frequently - making sure you change it before it's overly worn -- that you could go through several chain changes before changing the cassette or freewheel. Isn't the rule of thumb 3 chains or so for every cassette?

This is what I do. My chains last 1500 - 2000 miles, cassettes at least 5000 miles.

One more newbie question- just got my kmc x10.93 chain in the mail- should I clean the lube it is covered in before putting it on my bike?

I never do. I've got to tell you, however, it's a question about which people have real strongly held opinions that conflict with one another.

I was assuming the set-up was likely old. Never/mind.

I, too, always leave the original grease the chain came with. That stuff is good and it's in the chain really deep into the links. It seems a waste to take it off and re-apply something instead. So I'll ride it as is. Then I add a paraffin-based oil on top of it and ride that. Then I'll pull the chain and give it a good cleaning. Then more paraffin, etc.

I use Boeshield T-9 on my chains. It's excellent.

I always clean the original lube/grease from the chain before I install it, then use my fav lube (Pro Link). I picked up this habit from mountain biking. That lube is rather sticky and acts like a dirt magnet, even on the hardpack trails around here. Plus, I'm not fond of mixing new chain lube with the factory grease - it just doesn't seem right.

As Retro said, this is one of the hot topics on BF.

Do I need a chain tool to shorten the chain? I am kind of confused on how to go about doing this. Thanks.

You need a chain tool to shorten your chain.

Yes you do, there is no other safe, effective, non-damaging way to shorten a chain. Buy the correct tool and have the LBS show you how it's used.

As to using the old chain as a length guide, that assumes the chain was sized correctly to begin with. The optimum length is to wrap the chain around the largest chainring and largest cog without going through the rear deraileur. Overlap the ends and add two half-links (i.e. 1"). Here is Sheldon Brown's description: http://sheldonbrown.com/derailer-adjustment.html#chain Scroll down to "Chain Length".

Park Tools web site also shows the same technique. http://www.parktool.com/repair/readhowto.asp?id=26

BTW, if your old chain was "stretched" between 0.75% and 1.0%, it is very likely the cassette needs to be replaced too as the new chain will almost certainly skip on the smaller, most used cogs.

I'm of the school that says leave the factory lube in place. Wipe the excess off the outside of the chain if you wish but do not solvent soak the chain to remove it from the interior.

Please do a search. This topic gets beat to death nearly every day. Some of the posters above apparently never read becasue they post the same poor info over and over.

http://www.bikeforums.net/showthread.php?t=579617

You do NOT change a cassette with every chain. Cassettes need replacement if a one or more cogs skip when the new chain is installed.

To set the chain length, route the chain through the RD and shift to the little ring and smallest cog. Make the chain as long as possible without hanging loose or rubbing on the RD cage. Most road bike will have a length of 53 or 54 inches.

If he's replacing a known correct chain (albeit worn) there's no issue at all matching link for link. That said, your method is technically incorrect. Should be big ring to big ring + 2 links per Shimano.

Here is a thread that should help you with chain-length and what to look for:

http://www.bikeforums.net/showthread.php?t=579564

Hope it helps.

First, the big-big+ 1" sizing method assures the chain will never be too short for that inadvertant shift which can cause great damage if it isn't. Your method only guarantees the chain won't be slack in small-small and is of little value. You assume the rear derailleur has the wrap capacity to cover big-big AND small-small which is not always the case, particularly if a smaller chainring or larger rear cog has been substituted for the stock items. We've had this discussion before and agree to disagree.

Second, I agree that you don't have to change the cassette with every new chain but the OP said his chain was elongated over .75% and that makes it very probable the cassette is noticably worn too.

The little/little will always suggest a LONGER chain than the big/big unless the cassette being used is has the maximum range the RD is rated for. Then it will suggest the SAME length.

If someone builds up a bike that has more wrap than the RD can handle, and then using the big/big would suggest a length that will let the chain hang loose and flop around in as many a four of the smallest cogs. That's a stupid setup.

It really pays to know what you're doing if you're buying cassette with a greater range than manufacturer offers. In that case, a longer cage RD is almost always the proper solution and the chain length suggested by the little/little will produce the longest possible chain.

I'll bet the OP used a Park chain checker to get the .75% number, so it means nothing. It always pays to try a new chain first. I expect 3-chains worth of use from my cassettes and a lot more miles than the Park chain checker would suggest.

My method will produce a length that will work with any cassette within the RD's wrap capacity. If the big/big is used to setup a chain with an 11-23 and then the user wants to change to a 12-27, the chain will be 1 inch too short. My method will produce a length that will handle either one.

The big/big merely suggests the shortest possible length and may also suggest a length with two ends that can't be joined. In that case you have to add 3 links.

No it's not stupid. If you exceed the derailleurs rated wrap capacity, (as I do routinely by substituting a 26T chainring for the stock 30T for road triple cranks ) the worst I've seen is the smallest one or two cogs aren't usable with the granny ring. So what? That's absolutely no sacrifice. What possible use is the granny with a 12 or 13T cog?

If you don't allow big-big, the consequences can be very expensive if the bike is inadvertently shifted into that combination. As to substituting a XXx27 for an XXx23 and expecting the chain to be the right length, that's not reasonable.