Chain slipping on front chainring

lee_d_m

Hi,

I've been having some problems in the last week or so with my chain slipping of the large front chainring when putting the power down.

Having had chance to clean and look at it today, it looks like the chainring is worn, most of the teeth are looking very pointy, like sharks teeth

The chainset is a Shimano Sora 9sp, the large chainring is a 50.

I'd like to try to fix this myself, so would appreciate some advice on the following:

Should I just replace the front chainring, or will I need to replace the chain as well (FWIW, bike runs fine when on small chainring)

I did a quick Google for a Sora front chainring, but can only find a 34 from CRC, any ideas where I can get a 50 ?

What tools will I need to carry out the work ?

Any other suggestions ?

Thanks, Lee

bikeit65

What front chainring do you use most often?

lee_d_m

On this bike, I've always had Sora 50-34 on the front. This is fine for me as its a training/commuting bike so I don't want to spend too much. Just the minimum to get it working properly again.

farrina

You don't say whether the drive chain components are of the same age.

I have never experienced chain slip on the front (common on back with new chain on worn cassette or vice versa). Is it not jumping on the back or could it be a stiff link ? (rotate chain backwards and look for jump over jockey wheels).

Personally if you are replacing chainring I would consider replacing the lot (cassette, chain and front inner).

Madison are the importers here http://www.madison.co.uk/productinfo.aspx?&catref=Y1NB98070

You will have to find a dealer to order one for you e.g. http://www.swinnertoncycles.co.uk/components-c169/chain-rings-c208/road-c210/fc-3550-chainring-50t-f-black-p32988

Check for the correct part number here ( general Sora bits) http://techdocs.shimano.com/techdocs/blevel.jsp?FOLDER%3C%3Efolder_id=2534374302051120&ASSORTMENT%3C%3East_id=1408474395181679&bmUID=jWLMeWP

I would not bother with the chainguard version.

Regards

Alan

bikeit65

You say the chain is slipping on the big front chainring, so do you use the big ring most often?

JayKosta

Check for chain stretch by having chain on large ring and then pulling the chain outward from the ring at about the 3 o'clock position. If the chain pulls less than 1/2 a tooth depth from the ring then the chain is probably ok - if it pulls 1/2 or more away from the ring then change the chain too.
If the teeth on the small ring don't appear to be worn, then it is probably ok.
Also look carefully at the teeth on the cassette gears, if they are worn change it too.

Proper operation of the drivetrain depends on all the gears/rings/chain fitting together fairly precisely. Mixing worn and new can be troublesome.

For tools, the bolts for the rings is probably a 5 or 6 mm allen head, and you need a tool or flat screwdriver to hold the 'nut' on the back side. You'll probably also need to remove the crankarm, so that's another tool.
Probably a chain tool to remove the old chain, and to adjust (cut) the length of the new chain.
Tool to remove the cassette lockring.

For best shifting, replace the large ring, chain, and cassette.

After YOU inspect the various parts go to local shop and ask them what they would do and charge to fix it. Understand that the shop wants to make the bike work fine the FIRST time, so that you don't need to come back for another part that 'seemed ok at the time' - they might want to replace all the parts that aren't in 1st class condition.
Their reputation depends on them really FIXING the bike without any come-backs!

If you want to DIY and try 1 part at a time, and buy the various tools, that's fine. But it can be annoying and time consuming....

And YES, I usually DIY and make the usual 'amateur mistakes'.....

Jay Kosta
Endwell NY USA

lee_d_m

Hi, thanks for all your advice, I'll do the chain stretch tomorrow.

To answer the other questions.

I use the large chainring most of the time, usually drop-down to small for anything over 5-6%. Although I avoid cross-chaining.

The chain slips the most when I'm pulling away from stationery or when powering up a short hill whilst on the large chainring. It's also slipped on a couple of occasions when I've gone over a bump in the road.

I have not once had it slip when it's been in the small chainring, and I do a lot of hill climbing so put a lot of pressure through the small chainring when doing this.

Looking at the teeth, the rear cassette and small chainring look fine, still fairly squared off rather than pointed.
I also noticed today that the chain doesn't fit snugly into the teeth on the large chainring, I would need to push the chain into the teeth to get it fit snugly.

I also noticed this on CRC, this would work wouldn't it ?

http://www.chainreactioncycles.com/Mode ... elID=38169

Thanks, Lee

doug5_10

Have you replaced any other parts from new of the rest of the drivetrain? I would expect to be through 2-3 cassettes and 5-6 chains before a chainring would need replaced.

lee_d_m

Hi, I bought the bike in Sept 2010, if I remember correctly, at the beginning of 2012, I had both front rings, rear cassette and chain replaced all at the same time (I didn't realise the benefits of chain/drivetrain maintenance until then). Since then, I've ridden the bike about 5 days a week and usually clean the chain/drivetrain weekly.

The only thing I've had done recently was had a new bottom bracket fitted, this was done about 6 weeks ago, coming to think about it now, the chain slipping has started fairly soon after that. Seems unlikely but could the bottom bracket replacement have anything to do with it ?

doug5_10

Get a chain wear tool and check your chain, this is far more likely to be the cause of slip than the chainring. When replaced after appropriate wear, a cassette should last through 2-3 chains and in turn chainrings through 2-3 cassettes.

vanleapo

It sounds as though the outer chainring is worn, so you will definitely need to change it along with the chain, and most probably the cassette.

I found this Tiagra 50 tooth chainring at Evans, it may fit but not sure as I'm a Campagnolo man
http://www.evanscycles.com/products/shi ... 4#features

You will need a chain that matches your set-up, 9 or 10 speed. Shimano have a pretty big choice of chains.