labelcd6

Ok, I've searched the forums. I've Googled it. I've read Sheldon Brown's page. I've looked in Zen and the Art of Road Bike Maintenance. Maybe I'm just obliviously missing the information everywhere, but I can't find any real chain information!!!!! AHHH!

1. I ride a Trek ZX 6500. Can I buy just an ole 3/32 chain (I don't real know what 3/32 means. I just read that you should only get a 1/8 chain for fixies********** What?).

2. I have read Park Tool's website that provides some excellent information on sizing a chain. The only problem is that it seems excessively complicated.

3. Is it really this hard to find and size a bicycle chain???

4. Flame away!

caloso

The more cogs you have on your cassette, the narrower your chain needs to be. So if you have a single speed, you can use a 1/8 in chain; 5, 6, or 7 speed cassette, you can use a 3/32 in chain. Once you get above that, it tends to be really finicky.

I'd just go to the LBS and say "I need a ___-speed chain."

bikinfool

8 speed chain is the same as 7 speed chain...9 speed is a bit narrower and 10 speed is a bit narrower than 9.

OP when the 6500 was introduced it was a 7 speed, then became 8 speed, and the current 6500 is a 9 speed. Just ask your shop to install the appropriate chain for your bike...or do you think can handle a chain tool? Like Caloso said, ask the shop for a chain to match your drivetrain. Here's the basic definition of 1/8" vs 3/32" chain, guess you missed this on the Sheldon Brown site https://www.sheldonbrown.com/gloss_ch.html

noglider 

3/32 is a width, in inches. It's 1/32 inch narrower than a 1/8 inch chain. In the 70's, as far as I know, there were two widths of bike chains, 1/8" and 3/32". Now there are many.

I wish we still used measurements in inches or millimeters. I don't know how wide a 6/7/8-speed chain is. I just know it's less than 3/32".

operator

1) Count the number of cogs in the rear = speed of chain you need. It's obviously going to be 3/32. This needn't be mentioned when asking for $SPEED chain.
2) No, it's not. Pick one method and do it. Large large is quite simple. And give the shortest possible chain length. There are huge and lengthy debates on which one is "correct" or "better". Use search if you want to learn more about that
3) No.

operator

No there isn't. You have no idea what you're talking about.

3/32 is the internal width of chains, 6/7/8/9/10 speed chains are all "3/32". Only their outside width changed. The number 3/32 is nearly irrelevant to the OP. Any bike with 6+ gears is obviously going to be a 3/32 chain no matter what. As already mentioned the only thing you need to know is how many cogs you're running in the back = speed of the chain needed. The Trek bike the OP has is going to be 7 or more gears in the rear if it has the stock components.

Road Fan

When I got my parts for my Ergopower build a few years ago, the ultranarrow Campy 10 speed chains had just gone to 5.9 mm, down from (I think) 6.1. In English measure we really don't have a convenient way of talking about such small differences. Should be metric!

DaveSSS 

These days you buy chains by the number of cogs on the cassette. All 10 speed chains now have about the same 5.9mm width and are completely interchangeable from a width standpoint and of course they all have the same 1/2 inch pitch.

If your bike is a 9 speed, any 9 speed chain should work.

labelcd6

Thank you very much. I shall buy a 3/32 chain and use the large/large method. I do know my way around a chain tool...somewhat. I'm just interested in having a spare chain ready so that it doesn't interrupt my daily commute.

DaveSSS 

The little/ittle method will produce the longest chain length and maximum wrap capacity from any RD. Route the chain through the RD as normal and make it as long as possible without hanging loose or rubbing the RD cage. If that length is not long enough, you have exceeded the RD's wrap capacity. I would never use a setup that exceeded the RD's wrap capacity. If you do that, then the chain will either hang loose in several of the smallest cogs or fail to wrap the big/big. The possible exception would be a triple, where the little ring and several of the smallest cogs are not used. The chain hanging loose in those cogs wouldn't matter.

operator

On compatible components, you still shouldn't get any slack chain in any combo. Ideally. A new bike shouldn't be spec'ed by a customer or the shop to have such a situation ideally.

caloso

Personally, I use the little-little. I usually use a 23 or 25 tooth cassette, but I keep a 27 around for hilly races. Since little-little gives you the longest possible chain, I don't worry about snapping the RD off if I swap cassettes.

HillRider

It does if, and only if, you stay within the total teeth capacity of the rear derailleur. Exceed that and little-little can result in a too short chain to accommodate big-big.

caloso

That's true. But since I've never used anything bigger than a 27 (although lord knows I needed it), it hasn't been an issue.

Jed19

If I switch frequently between wheelsets with 12-23t, 12-25t and 12-27t cogs, then I should size the chain using the large/large method with my 12-27t cassette?

Right?

Or, would the 12-27t large/large sizing result in "too much chain" when I switch to a 12-23t cog wheelset?

operator

Large/large is the optimal method since you are sizing it for the biggest cog you will be ever switching to. This method gives the shortest possible length - which is what you want. Depending on your derailleur, you may run into chain slack issues in the small ring/small cogs.

DaveSSS 

If you swap a triple's 30T ring for a 28 or 26, you might get a slack chain in the smallest two cogs, but it will not hurt a thing. That can happen with a 53/39/28 with a Campy medium cage RD.

Of course if you're building for the public and not yourself, you have to assume the customer is clueless.

DaveSSS 

Lucas...

What is often ommitted from the big/big explanation is that the ends of the chain that come togther may not match up. In that case you add 3 links, not 2.

The little/little method has no ambiguity to it. If you know the RD's wrap capacity is sufficient, you want the longest chain possible. With a 12-27, both methods should suggest the same length.

With a typical Shimano short cage RD, there is enough wrap capacity to handle any road cassette Shimano offers, using only one chain length.

Jed19

Thanks DaveSSS. I have an Ultegra 6603 (53x39x30) crankset and an Ultegra 6600 long cage RD. What I've always done is to size big/big with the 12-27t cogs. I've never had any obvious problem(s) with my chains when I switch wheelsets, but then again, I'm no bike mechanic extraordinaire/genius

noglider 

Well, I learned something. Again.

I wish they told us how wide they are internally, in that case. That way, we could make more informed decisions and guesses about what chains will work with what other equipment.