I have road bike, tiagra shifters, tiagra front der, XT rear der, 9 speed super narrow KMC Z9000 chain.


The chain is broken and I plan on using it until new chain arrives.


Here are my choices: https://home.earthlink.net/~kmcchain/english/index.html


Obviously I can go with a different brand, whatever is cheaper.



My questions are:

Do I have to go with 9 speed super narrow chain? Can I used a tougher BMX/freestyle chain instead? Which once from that manufacturer's?


Does my chain have to be a certain length (such as the length I have now)? Can it be longer? If so is that good or bad?


If I go with a heavy duty chain, if it's possible, what kind of benefits will I experience on a road bike? Any performance issues?

You need to go with a '9 speed' chain because the width of the chain is important. The width limitation is to do with the spacing of the sprockets on your cassette, they need to keep it to that width to squeeze all the sprockets in there. Just out of interest, the 10 speed chain is even narrower again and the BMX (1/8 inch) is too wide. Don't worry about strength, when set up correctly the chain is very strong, somewhere in the order of 10K newtons if I remember correctly.

The length of the chain is also important, the critical factor is to allow sufficient chain so that it will go around the largest chainwheel (front sprocket) and the largest sprocket on your cassette at the same time. Just wrap the chain around the largest sprockets and allow one or two extra links and that's the right length. You'll also need a chain breaker tool to set it up correctly, don't worry they're very easy to use.

I've used 9-speed shimano and sram chains, they're both very good. I also use a wippermann quick release link to easily remove the chain for regular cleaning. Not critical but if you're fussy about maintenance (as I am) it's great.

...just one other thing about the chain being longer. You don't want it too long because the rear derailer has to take up the slack, and you already know what happens if your rear derailer is unhappy

[edit] I just found Sheldon Brown's page on chains and rear derailers. I highly recommend you read it then read it again and take it all in. Sheldon is Encyclopaedia Biketannica and his site is the best d.i.y. bicycle maintenance info on the net.

https://sheldonbrown.com/derailer-adjustment.html#chain

Yea, I read that before posting. It appears I'm going with SRAM chain, instead of cheap KMC.. But we might see about that, if I can find a cheap X9 from KMC then I"m going with that...

I took a small hill with my old chain, in 1st 3rd, and rear last or something like that. From a complete stop. I heard some tearing and stretching, or something that didn't sound nice. So I presume strength of the chain is all relative. I kind of want the strongest.

Can't comment on KMC as I haven't used that brand.

I'm not sure what you mean by "1st 3rd" but it sounds like you may have been crosschained. If you look at your bike from behind you'll see that the front and rear sprockets line up approximately so that the large front is more in line with your small rear (your highest gear) and your small front is approximately lined up with your large rear (your lowest gear).

What you want to try to avoid is having your chain on the large front and large rear or small front and small rear because it would put your chain at a a sharp angle where it meets the sprockets, that's called crosschaining and it's not real good for the gears.

The noise you may have heard could have been the chain straining in a crosschain and rubbing against a derailer cage. Even so, I think there was something faulty in the assembly of your bike, probably the pin where they closed the chain wasn't properly seated, or the derailer wasn't installed correctly. I don't think you have anything to worry about in terms of chain strength with a brand new chain.