I need help with choosing the right chain

onyerbike531

Retro Guru
Hello forum people

I have an old racer bike with a Shimano EX300 groupset, well half of it at least, it looks like someone has swapped the original chainrings and chain for something that isn't compatible; there seems to be a load of slack in the chain which isn't taking to the teeth of the chainring properly and it is struggling to stay in gear despite me adjusting the rear derailleur, nothing seems to be working. This particular bike originally came fitted with biopace chainrings but they've been swapped out for something more conventional and not up to the job. I wanted to know what type of chain would be compatible with the Shimano Exage 300EX groupset with a 7 speed cassette. Is there any modern double chainrings that would also work with this setup if I wanted to change the chainrings.

Thank you
 
Any chainrings should work, as most modern chains (apart from singlespeed) all have the same internal width. An 11speed chainring might be a little thinner than an 8-9 speed chainring, but to be honest you can run anything on anything. I have 8speed chain running on 6speed chainrings, 8speed chain running on 9 speed chainrings and 9speed chain running on 11speed chainrings.
As for a new chain, a 7/8 speed chain from Shimano will be perfectly good (I got one recently for about £10), and they work admirably for the price. You could use 11speed to save weight, but it will wear a little faster due to the thinner plates.
 
KMC would be a decent Chain to use & many choices to choose from in there line up.
 
Thanks for replying, only just logged back in to see your replies, my local bike shop sold be a Clarks quick link chain and after a couple of attempts at shortening it to the right length I managed to get it on.

After changing the chain it's started to function better but I've now got an issue with the chain slipping in the 4th gear and occasionally in the 3rd but nowhere near as much; it seems to happen when I pedal harder, I've tried setting up my derailleur properly using the H and L screws, fine tuned the cable tension, even changed the gear cable.
The kid in my local bike shop said that there might be some wear to the sprockets on the cassette and recommended that I change it so I've bought myself a replacement shimano 7 speed one, I'd like to to have a go at fitting it myself as I need to improve my skills as a cycle mechanic; there are some good instruction videos out there especially GCN etc but I can't see what kind of adaptor they'd be using on the end of the torque wrench, what would I need to attach to the torque wrench to enable me tighten up the lock ring to the required torque stated in the instructions, a torque of 40N

Thanks for being so helpful
 
Cassette or Freewheel?
I seem to recall they both apparently require the same tool, but I have found one is rather different to the other, despite a similar size and number of splines - I have one for cassette and one for freewheel. You should be able to buy a tool from any half decent/long established LBS. As for torque, I've never torqued up a cassette - just put it on hard, but so you still stand a chance of removing it when you want to - and freewheels are self-tightening.
 
It's a cassette, you're right about the freewheel tool being different I've done a bit of research and the splines are slightly narrower on the freewheel tool, managed to find a shop that's selling cassette removal tool. They look very similar don't they.

Ok thanks for that I will tighten it up well
 
You will find that if you fit a new chain and use it on an old cassette it is likely to 'jump' on one or more of the sprockets, as the sprockets will have worn down with the old chain, so fitting a new chain is going to cause it to jump as you are meshing a new chain on worn sprockets. This usually happens with the middle sprockets as these are the ones that will see most use.
You can check for chain wear by measuring the chain with a ruler (Youtube videos show you how and what to look for to indicate the chain is worn and needs replacing). A quick way of doing this is putting the bike in the big ring/smallest sprocket, and trying to lift the chain off the chainring at the point where the chainring that is closest to the front of the bike; if you can lift it off the teeth then the chain is worn.
You can sometimes get away with not needing to replace the cassette at the same time as the chain, if you replace the chain early. If you leave it too long the cassette will wear out (as has happened in your case); and leaving it even longer and continuing to use it, then the chainrings will also wear out (again, as has happened with you also).
Regarding chain types, I find KMC chains are really good. If you need replacement chainrings, I can recommend Stronglight as I've just got a new set for my winter bike and the finish on them is really good - they are more than a match for anything from Campagnolo or Shimano.
 
Ok I will get on to changing the cassette, I've ordered a new Shimano 7 speed and I'll be fitting it next week, I've already put the new chain on it but I'll look out for a KMC next time on your recommendation, I've only rode the bike to the shops with the new chain on it so not put too much more wear on it. I bought the bike secondhand and it looked like someone had fitted a unsuitable chain which I think has caused the damage to the cassette, it hadn't even been tensioned and wasn't even sitting properly between the teeth of the chainrings.
 
For what it's worth, chains 'designed' for 8 speed will also work with 7 speed. 9 speed chains will also work as they are the same internal measurements. Look for cassettes from Sunrace, Sram as well as shimano.
 
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