7

I got a second-hand bike some time ago. It's a Zündapp Silver 2.0 with a 7-gear freewheel (Shimano MF-TZ21). Recently, the chain (probably KMC 1/2 x 3/32) has worn down enough to warrant changing. So I remove the worn-out chain and count the chain links to size my new chain and figure out, to my surprise, that it has 118 links.

I bought a Shimano HG40 chain with 116 links for replacement, which is why I am now puzzled why it wouldn't be enough out-of-the-box (as in, it is even short by two). In fact, the only 118 links I could find is this but it is for 11-speed mountain bikes. I've tried sizing the new 116-link chain on the actual gears and it seems 116 should do the trick. Nonetheless, I don't want to commit to 116 until I'm sure. Besides, I never had a problem with the chain until it's worn down.

The parts I mentioned above are the default parts of this model (some info might be hard to find in English). I bought the bike from a coworker whom I've lost contact with and at the time of purchase, he was diligent enough to mention which parts of the bike has been repaired or might need repair soon. Neither the freewheel nor the chain came up so that's at least one reason to believe these parts haven't been serviced before.

Is there any reason why the old chain had 118 links on? Should I just change it to 116 or should I patch together a 118-link chain? As it is my first time changing chains, I'm worried that my assessment that 116 links should do the trick on the actual gears is wrong. Also, honestly I'm just a bit bummed to have to buy another Shimano HG40 just to nip off two links off it.

Improve this question
5
  • 1
    Chains are “cut” to size by removing pins and links, depending on the size of the cogs and length of the chain stay. The number of gears has nothing to do with it.
    – Paul H
    Commented Jan 15 at 17:55
  • 1
    The number of gears you have on the bike won't have much, if anything, to do with the length of the chain you need. The main factors will be the sizes of the gears you have (largest & smallest), and the size of your frame (the distance between your crank and the rear dropout).
    – Greg
    Commented Jan 15 at 17:56
  • 1
    Could you give us a photo showing the chain on the bike, with it resting in the largest chainring and largest rear cog? Something like this : dgtzuqphqg23d.cloudfront.net/…
    – Criggie ♦
    Commented Jan 15 at 18:19
  • 1
    @Criggie unfortunately the bike is totally unchained at the moment; the worn-out chain is removed (with no intent to put it back on) and the 116-links is not yet installed. As things stand, I think I would extend this to 118 anyway.
    – skytreader
    Commented Jan 15 at 19:40
  • 1
    I have seen bikes where someone has changed the chain but not trimmed it to length, and the bike is just wearing whatever length was in the box. It could be your bike doesn't need that many links, hence the photo.
    – Criggie ♦
    Commented Jan 15 at 20:41

2 Answers 2

Reset to default
10

There is no standard for chainstay length. Bikes of a given type tend to cluster around certain very common chainstay length choices, but there can be outliers in eitehr direction. Thus there is nothing resembling a true standard or default size for chain length (or link count) for any given genre of bike. Among derailleur bikes, 112, 114, 116, and 118 all come up as needed lengths regularly.

There is no relationship of any kind between chain length and the number of speeds a bike has.

Chains are typically sold in a length that's the longest an applicable bike might need, and then they are expected to be sized down as needed when installed. (This doesn't always go right, but it is the idea).

Improve this answer
2
  • Thanks. I updated my question to reflect why I'm bewildered that I need 118 links in the first place. I guess this really means I gotta find the extra two links somewhere.
    – skytreader
    Commented Jan 15 at 18:35
  • Well, if you have a transmission with a large range you have a large front chainwheel and a large "smallest gear" sprocket in the back. If you ever plan to be able to cross-shift, even inadvertently, you need a larger chain to accommodate both at the same time. Even if you stay within the smaller few back sprockets on the largest chain wheel you'll need more links than with a smaller range and accordingly smaller large chainwheel. (And to compensate for the big "needed chain length" difference between the extremes, you need a long cage.)
    – Peter - Reinstate Monica
    Commented Jan 16 at 2:12
4

ANSWER: The bike's "speeds" is unrelated to the length of the chain.

Some bikes have short chainstays, some have long chainstays.

The main factor in required chain length is the size of the rear wheel, and additionally how much space there is between that wheel and the frame's seat tube for a conventional diamond/twin-triangle frame. Full-suspension MTBs, recumbents, tall bikes will diverge from this, while beach cruisers and crank-forward bikes would still conform.

Here's a bike that needed 125 links: enter image description here

And here's a short-chainstay bike that only needs 106: enter image description here

If the bottom bracket is not straight across the end of the seat tube then you may need more or less chain.

Improve this answer
4
  • 2
    That first bike is unsettling. Is the wheelbase required for a specific purpose?
    – Michael come lately
    Commented Jan 16 at 18:12
  • 2
    That's an early electric frame, there was originally a battery between the seat tube and rear wheel.
    – Affe
    Commented Jan 16 at 18:45
  • 1
    @Michael Alfie is right - Originally a cheap ebike frame I bought wrecked. I had a plan to test the effect of long chainstays when going up a steep climb. Specifically on how "lifty" the front wheel is. Upshot, it definitely makes a positive effect, but this frame was all steel and heavy, which negated the benefits.
    – Criggie ♦
    Commented Jan 16 at 20:33
  • 3
    I could show my recumbent that use about 270 links in a chain, and that is a 9 speed using normal bike transmission/gear components with some additional rollers, but that's getting away from OP's intention.
    – Criggie ♦
    Commented Jan 16 at 20:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.