Mechanical Issue

[Mohammad L]

Sorry folks - another little problem....

I was rotating the cranks backward and the chain was rattling - after only one revolution, the chain independently shifted down two cogs from a 28 tooth to a 21 tooth and jumped off the big front ring and past the small front ring to position itself between the small ring and the frame. The jockey wheel position sprung forward simultaneously.

This has only recently been happening when I rotate the crank backwards - the chain rattles and then independently moves down 2 cogs and goes off the front big ring to lodge itself between the small ring and frame. These events are accompanied by some weird movements in the jockey wheels linked to the derailleur

When I rotate crank forwards, everything is fine

(Gear shifting up and down the cogs is fine and smooth, as is shifting between small and big front rings).

Cassette is 11-28 10speed and chainset is 53-39

I don't really have a clue what's going on....Any thoughts?

Cheers

[Keith]

53x28 is a questionable "crossing" gear selection when going forwards, let alone when pedalling backwards.

The jockey wheels moving forwards when dropping from big ring to small ring is normal.

However, I'd start by looking at the jockey wheels. How much mileage have they done? How much play is there in the lower jockey wheel especially?
Also, is the chain itself in good condition? Within serviceable limits? Any tight links?

[Ian A4size]

Wot Keith said...... Cack chain line,

Also the free hub could be a bit sticky, I guess you were riding a trusty winter steed?

[Andrew G]

Ditto. That chain line with a big sprocket like that will have the cage pulled right out with the chain at an extreme angle.

[Mohammad L]

The 53/39 11-28 is my racing bike - only done about 800 miles. Jockey wheels look clean and not worn. Not sure about the other stuff - I don't have the tools/knowledge/ expertise to comment on the other aspects Keith - will probably youtube it. Anyway, I'm not too concerned about this anymore....

...what I'm v.anxious about now is my training road bike (50/34 12-25) :

Today went out for a ride and about 35 miles in, every time I was free-wheeling - the chain starting to rattle - I looked down and saw that it was brushing the front derailleur cage BUT the chain also seemed to 'want' to move down a couple of cogs.
I was trying to avoid free-wheeling but every time I turned a corner and free-wheeled, the same stuff happened.

Then, about 50 metres from home as I was free - wheeling (on 50 x 25) - chain rattling noise and then the pedals suddenly felt v.light, the cranks jammed up and I couldn't pedal forward and came to a halt (When I came to inspect it, the chain didn't come off - it was still on the 50 ring and 25 cog BUT the jockey wheels and rear derailleur had radically moved - they had sprung forward)
Now, the drive train is behaving very strangely indeed - I can rotate the cranks forward without lifting the back wheel (when I do this the back wheel doesn't rotate ie the cassette moves independently of the rear wheel in the drive-direction)

I don't know if this is worth mentioning or not - On the weekend, I did clean both my chains and my training bike cassette (12-25) and race bike cassette (11-28) using muc-off spray on degreaser and warm-ish water for the first time, and they came out looking almost like new. Since then, the jockey wheels have been playing up and all this other stuff.

...Sometimes I'm thinking - maybe this is happening now to prevent me getting on the bike - because now the training bike is a definite no-go

[Phil H]

Did you lube everything after cleaning? Lube is important.

If your freehub isn't engaging when you pedal forwards then that's an issue - normally indicating that the freehub is borked.

Always worth reading [url=http://sheldonbrown.com/chains.html]Sheldon[/url].

[quote="Phil the Pie"]Did you lube everything after cleaning? Lube is important.
.

[Phil H]

Not sure about Halfords. I have replaced a freehub myself on the MTB and it wasn't too hard. Have to be a little careful with the bearings (and not drop the little *******s all over the garage floor). What's the chain stretch like while you're at it? I tend to change when it gets to about 1mm over 12" (way to mix units) once it gets over 2mm in 12" then the cassette is likely gone too. Chainrings take longer but wear out eventually.

Bike+ might be a better option that Halfords. They have 8/9 speed stuff in.

[Ant]

You'll get nothing but problems from riding in big ring / biggest sprocket. Or small ring / smallest sprocket. You will wear chain, sprockets and chainrings prematurely and cause weird behaviour, like the chain jumping off the chainrings and slipping into other sprockets, especially when pedalled backwards.

That aside, if the cassette is not engaging the wheel, then the pawl springs inside the freehub might be stuck. Perhaps when you cleaned the drivetrain, some dirt got dislodged and has gunked-up the inside of the freehub body. I would take it to an LBS and steer clear of Halfords, for things like this. Either that or do some You-Tubing and have a go yourself, if you're feeling brave. Servicing the internals of a freehub and messing with pawls can be a little bit tricky.

Good luck and hope you get both bikes sorted, soon.

[Andrew G]

Sounds like the freehubs had it. The cleaning etc won't necessarily have anything to do with it other than conincidence, if it was about to go then it was about to go. If it was a cheap wheel then it's probably had it's time. Depending on the quality and/or type you may not be able to replace or service the hub/freewheel properly. If you look for new wheels for training then Campag Ventos are pretty bombproof and cheap. Alternatively get some handbuilt wheels done, and Bike+ or GBs will build excellent ones, and on my commuter for example I just get them re-rimmed when I wear the rims out, hubs etc all fine.

Drivetrains will work faultlessly for ages so long as you set them up properly and keep them maintained. Set up the indexing properly at the start and don't ride mad cross-over combos (e.g. big-big)

Replace chains regularly, replace jockey wheels and cassettes when required (much less often with regular chain replacements). Chainrings last ages as a rule but some compacts seem to have softer big rings (oo-er) as I've known a few peoples wear out quite quickly. I use 53/39 set ups and the chain rings last years, even on the commuting bike which does the highest mileage in all weathers.

For home mechanic have a look at the Park Tools website. Then have lots of step by step guides with pictures, print them out, read them and use them to do the jobs. They work well.