Jockey Wheel Clearance Problem

Secteur

My bike came with a 12-27 cassette and it's all 105 (5600).

I find that I have to screw the Tension-B Screw *all* the way down, and even then when I am on the turbo I notice that the jockey wheel still contacts the cassette in almost all gears and there is a noticeable "rumble".

I dont notice this problem on the road - just the turbo (but it probably happens on the road too - I just cant hear it with the road & wind noise vs in a silent garage on the turbo).

I assume a standard 105 derailleur is built to cope with a 27 sprocket? Especially as it was the one supplied with the bike (factory spec). My chainset is 50/39/30.

I only recently learned on here (http://www.bikeradar.com/forum/viewtopic.php?p=17187864&highlight=#17187864) that apparently the rear mech has a "capacity", beyond which it needs to be longer, but I have no idea how close to this capacity I am running.

Note, on the bike stand, there does appear to be a few mm of clearance between the jockery wheel teeth and the cassette teeth when in the biggest sprocket, but maybe under force this reduces?

merak

If it's the medium arm, capacity is 37T and you are running 20+27-x where x is the smallest sprocket on your cassette so you'll be within the capacity (with 2 or 3 to spare). The max sprocket size on the 5600 med arm RM is 27 so you're right on the limit there. But that should only be an issue when you're in the 27 - are you sure you have a sprocket to jockey wheel clearance issue? What happpens if you back the B screw off a bit? Is your chain the right length?

This Park Tool page might help you:
http://www.parktool.com/blog/repair-hel ... derailleur

malcolmfrost

27 should be fine, I run a 30 with a short cage Ultegra with no problems. It might well be that your chain is too long. Try taking one link out.

Secteur

How do I know how long a chain should be?

I assume the one that came with the bike would be correct??

merak

Just had a thought - is your rear wheel fitted fully into the dropouts?

gilesjuk

Secteur wrote:

How do I know how long a chain should be?

I assume the one that came with the bike would be correct??

Never assume

Wrap the chain around the largest from ring and largest sprocket, then add two links (the SRAM method).

Many of the combinations do not makes sense, you don't really want a chain that is going from the largest chain ring to the largest sprocket. Hence it will make a racket.

Secteur

Further to my other thread, I am still trying to figure out how to take the chain off!!

cougie

The Park Tool website probably shows you.

Did you fit the chain ? Cos a standard chain is always too long in my experience.

mrwibble

you mess far too much with your bike

markos1963

mrwibble wrote:

you mess far too much with your bike

If he didn't we wouldn't have anything to talk about on here!

malcolmfrost

Secteur
It depends on what type of chain, but if you're going to shorten it you'll certainly need a chain splitter, one might be on your multi tool.
SRAM technique +1
I was also shown another, with the gears in large sprocket and small chainring, the centres of the jockey wheels should be in a vertical line with the wheel axle.

Paul E

I have an 11-28 on mine with the same rear mech as yours and I don't have that clearence problem and my cassette is bigger.

Unless you really know what you are doing you might end up doing more damage.

markos1963

Have you been fiddling a bit? Only thinking about it logically why would Speciallized supply a bike with a set up that wouldn't work? I doubt that the B screw would have been wound all the way in in the first place, most bikes are set up from the factory with adjustment either way.

Leave the chain alone unless it's a different one to the one that came with the bike. Can't see how a too long chain would cause the jockey wheel to foul, more likely to be cause by a short chain.

malcolmfrost

Can't see how a too long chain would cause the jockey wheel to foul, more likely to be cause by a short chain.

Er no (I hope!) if you shorten the chain it pulls the derailleur more in a straight line and therefore pulls the jockey wheel away from the sprocket.
Secteur, try it without taking any links out and see if that helps.
Having said that are you absolutely sure that it is the jockey wheel, it is very unlikely that would happen in all the gears. In my experience a turbo is so noisy you'd be lucky to hear anything!

markos1963

malcolmfrost wrote:

Can't see how a too long chain would cause the jockey wheel to foul, more likely to be cause by a short chain.

Er no (I hope!) if you shorten the chain it pulls the derailleur more in a straight line and therefore pulls the jockey wheel away from the sprocket.
Secteur, try it without taking any links out and see if that helps.
Having said that are you absolutely sure that it is the jockey wheel, it is very unlikely that would happen in all the gears. In my experience a turbo is so noisy you'd be lucky to hear anything!

Yes your right, just been out and tried it on mine. But this begs the question that the chain gets longer, not shorter as it wears so it's unlikely to be a short chain.

MountainMonster

Are you ever going to be happy with your bikes, or is it just complaints from you?

merak

My vote is for the wheel not being seated in the dropouts...can't see why else the jockey wheel would foul the cassette in all gears. Or it's not fouling at all. It won't be chain length if this is the chain that came with the bike. And the B screw should not be all the way in.

kayakerchris

the other possibility is damage to the hanger. If you bang the rear mech against something then the hanger is designed to bend to protect the rear mech. This then effectively moves the jockey wheel closer to the sprocket, whatever you do with the B screw.

Look at the bike from the back and check if hanger hangs vertically.

Alternatively take off the hanger and lie it on a flat surface and then check that it is flat and not twisted/bent.


(I only know because this happened to me)

Chris

Secteur

MountainMonster wrote:

Are you ever going to be happy with your bikes, or is it just complaints from you?

I demand perfection in everything I do and own, so as long as my bike makes noises which I know are not normal, then I will chase them down. It's worked well for me so far and I now have a silent bike on the road (having correctly identified several factory & LBS set up faults & corrected them, partly with help from this site, and partly in spite of the people on here who said I should just live with it & who also said I was imagining it / over worrying!!!)

I was knocked over a few weeks ago and the rear derailleur was all scuffed & banged. The LBS said it wasn't bent at the time, but I haven't specifically checked it myself. That may be the problem.

malcolmfrost

I was knocked over a few weeks ago and the rear derailleur was all scuffed & banged. The LBS said it wasn't bent at the time, but I haven't specifically checked it myself. That may be the problem.

Ah!
If the derailleur isn't aligned then it may be the chain rubbing on the sprockets that's causing the noise.
You will need to get them to check the hanger alignment as above using something like this http://www.parktool.com/product/derailleur-hanger-alignment-gauge-dag-2.
If that's OK then I would probably replace the rear derailleur. They're not desperately expensive £45 from Halfords.
BTW don't worry about being a perfectionist, we all learn from this and the more you know about your bike the better!

markos1963

Secteur wrote:

[
I was knocked over a few weeks ago and the rear derailleur was all scuffed & banged. The LBS said it wasn't bent at the time, but I haven't specifically checked it myself. That may be the problem.

Is this the same LBS you said didn't set up the bike properly in the first place?

Secteur

markos1963 wrote:

Is this the same LBS you said didn't set up the bike properly in the first place?

err.... yes! And wont be going back there - ever!



I did some careful testing last night - with the B-tension screw fully down it just still bumps against the large sprocket (just a tiny bit).

With the B-screw out a bit (even 2 or 3 turns) - the jockey wheel grinds against the sprocket much more.

Never used to do this, so I assume it to do with the accident I had.

As soon as the solicitor gets the woman who knocked me over to pay up I can get it all sorted.

merak

Ah - well you did say it was fouling the cassette in all gears which sent some of us off on a wild goose chase.

Secteur

sorry, but the discussion is still useful!