Help! Confused about chain & cassette

[benjus]

Hi everyone,

I'm a bit of a novice at bicycle maintenance but I'm keen to learn, so any advice is appreciated.

I have a Genesis Day 00 2007 bike. I've had it about 15 months and use it for commuting and general utility cycling in London. A couple of weeks ago the rear derailleur somehow got damaged and broke off. I spent most of the week sourcing a Shimano Sora 8 speed derailleur and the correct dropout. I fitted them and everything seemed fine for a few days.

Then a couple of days ago the chain broke. I guess it was down to my manhandling of the chain tool. So I went to Evans and asked for a new chain, and ended up with a Shimano HG40. Comparing it with the old chain showed that the old chain had stretched a fair amount.

I fitted the new chain, and now the chain is skipping over the some of the sprockets, making it almost unridable. However, while it appears to skip to some extent on most/all of the sprockets, it only does it badly on the middle range of the rear cassette. Looking at the sprockets some of them appear quite worn, especially around the middle range.

This led me to think that I would probably need a new cassette, so I started looking up the spec for the bike. I noticed that the chain specified was an HG50, so I'm wondering if I bought the wrong chain.

So, my questions are:

• What is the difference between HG40 and HG50 chains?
• Should I buy a new chain (HG50), a new cassette, or both?
• Which cassette should I get? (the specs I've found just say Shimano Cassette 12-25 8sp)

Sorry for the long post... any help is much appreciated.

 

[spandex]

HG50 is better then the HG40. your new chain will be fine if you get a new cassette About the new cassette just get the same as that is on the bike. Don't forget you will need the tools to get it off and on which will cost but then you will have the tools for life. If you don't want the extra cost you can ask the LBS to do it for you if they do charge it wont be much.

 

[Gerry Attrick]

Hi benjus.

AFAIK the only difference between hg40 and 50 is quality and price. Provided they are designed for eight speed, either will be fine.

As you say the teeth are worn on your existing cassette, you won't get a new chain to run satisfactorily on the sprockets. Get a new one.

Any of the Shimano eight speed cassettes will be fine. Again the differences in price reflect the quality.

 

[benjus]

Thanks for the replies guys... the cheapest suitable cassette on Chain Reaction cycles is £12 for the Tiagra 8 speed HG50 (http://www.chainreactioncycles.com/Models.aspx?ModelID=1864), which seems like a reasonable price to me.

Could you tell me what tools I will need to change the cassette? Something like this (http://www.chainreactioncycles.com/Models.aspx?ModelID=7975)? Anything else needed?

 

[Landslide]

That will take your lockring off, you'll also need a suitable spanner to turn it (a large adjustable should be fine), and a chain whip to stop the cassette spinning round whilst you undo the lockring e.g.
http://www.chainreactioncycles.com/Models.aspx?ModelID=10184

 

[John the Monkey]

I have that cassette tool - it should be fine, although it does need a big spanner to fit the nut at the top, as I recall (either a 25mm or 26mm).

Changing a cassette is a simple job, see here;

http://bicycletutor.com/replace-cassette-cluster/

 

[bonj2]

to get the cassette off you'll also need an adjustable spanner to grip the lockring, an old chain, and a car - and also a towel or old sheet or towel to protect the car's wheel.

 

[Mr Pig]

A good investment is the bike tool kit that pops up in ALDI or LIDL now and then. You can buy similar ones on line although they have slightly less stuff in them and cost a little more.

http://cgi.ebay.co.uk/44pc-Universal-bicycle-bike-repair-tool-kit-set-Case_W0QQitemZ110276994192QQcmdZViewItem?hash=item110276994192&_trkparms=72%3A984|39%3A1|66%3A2|65%3A12&_trksid=p3286.c0.m14.l1318

With postage that's £10 more than out of ALDI but it's still good value. Buying a chain whip and cassette tool separately will cost you more than half the price of this whole kit. It has both, plus most of the other tools you'll need. Whilst not the best quality it is not bad and the importaint tools are pretty solid. I have this kit and a Shimano cassette tool and there's not much difference between them.

 

[MartinC]

The worn chain wore out the sprockets too. When they were both together they worked reasonably well - the stretched chain matched the hooked sprockets. When you changed the chain it didn't fit the worn sprockets so well so it started to skip. If you change the chain before it wears out the sprockets will last longer.

 

[John the Monkey]

FWIW, I like the linked Cyclo pro tool more than the cassette tool in the Lidl kit (the shape is better, and the metal seems "harder"). The tool in the Lidl kit can be used with a smaller spanner though (if you use an open spanner) as it's not shaped as a hexagon with equal sides (narrrower between two of the sides).

 

[benjus]

Thanks everyone... that's cleared it all up for me.

Mr Pig - that tool set looks good, although I already have a fairly good set of standard workshop tools and several cycle-specific tools. I'll have a think about it...

MartinC - yes, that's what I've learned now... I'll remember to change the chain in future!

 

[John the Monkey]

Benjus, sheldon brown's site has a good article on chain wear here;

http://www.sheldonbrown.com/chains.html#wear

Gives a very simple way to figure out how worn a chain is using a steel rule or tape measure too.

 

[benjus]

Benjus, sheldon brown's site has a good article on chain wear here;

http://www.sheldonbrown.com/chains.html#wear

Gives a very simple way to figure out how worn a chain is using a steel rule or tape measure too.

Thanks... I came across this recently too - sadly after the damage was done.

Sometime I should sit down and read everything in the Sheldon Brown site so I don't get caught out in future...

 

[Mr Pig]

The tool in the Lidl kit can be used with a smaller spanner though...

But why use a spanner when it's designed to take a 1/2-inch drive ratchet/lever?