Chain wonkiness?

rubez

I am nearly finished configuring my bike.

I have arrived at the FINAL, but complicated hurdle - possibly gears or chain-releated.

I mean, it works technically, but I am not 100% happy with it.

My chain seems to wobble, or is shaky/out of true when in operation - also the rear derailleur seems to pulse gently, on a regularly cycle, is this normal? It also looks unparallel to the bike - a bit squint.

When setting up the gears, the B-screw didn't seem to change a thing when I adjusted it, so I don't know if that is set OK.

When pedalling upside down, the chain would rub off the front derailleur mech at certain points, also on a regular cycle, suggesting something is out of shape? - so I have adjusted the front derailleur probably more than I need to, to compensate (it is supposed to be adjusted to be just shy of the chain) ... but I finally got all 3 of the front gears working without any rubbing on the mech thing.

But - shifting down from the large chainring seems not as smooth as it should be, and I am getting a dramatic sword-unsheathing sound when it downshifts! (SCCHHINGG!!!)

I have checked with guides online, and my chain seems to be exactly the correct size, even though it seems shaky.

Don't know where to start really :shock:

Any thoughts on this?

cooldad

Parktools?

rubez

Tried it, doesn't seem to have anything on this rather specific problem.

They only cater for all the generic problems and procedures.

drlodge

Turn your bike the right way round (not upside down) and go ride it. Then see if you have any problems. Bike's weren't designed to be ridden upside down you know.

nicklouse

rubez wrote:

Tried it, doesn't seem to have anything on this rather specific problem.

They only cater for all the generic problems and procedures.

No it tells you how it set it up.

You have not set it up correctly.

rubez

I set it up exactly like every other person sets them up... It's like lego, there is only one way.

Could you be more generic please?

Also, upside down testing shouldn't result in this.

rubez

I can post pics later if that'll help.

I know it sounds complex, but what about the 'SCCHHINGG!!!' noise?

Is that telling of anything? Pretty sure that's abnormal...

drlodge

rubez wrote:

I set it up exactly like every other person sets them up... It's like lego, there is only one way.

Could you be more generic please?

Also, upside down testing shouldn't result in this.

If there's only one way to set it up, you must have done it the right way

You want us to be more generic, when you have a specific problem? If you want generic, try parktools

On what basis do you say upside down testing shouldn't result in this...even if it shouldn't, it might, so test it the right way up with you on the bike pedalling.

Please god, give me the strength to ignore these posts and save precious minutes from my life. :roll:

rubez

The derailleur that is skew-whiffed, is like that upside down, and right way up.

It should run parallel, no?

So, that may be part of the problem, or a symptom...

JodyP

rubez wrote:

I set it up exactly like every other person sets them up... It's like lego, there is only one way.

Could you be more generic please?

Is that sarcasm or did you mean specific?

I think a picture might help your cause.

welshkev

rubez you are a true genius

when is supersonic going to own up that this is his alter ego?

rubez

JodyP wrote:

rubez wrote:

I set it up exactly like every other person sets them up... It's like lego, there is only one way.

Could you be more generic please?

Is that sarcasm or did you mean specific?

I think a picture might help your cause.

I was chanelling John Oliver from The Daily Show.

Will get some pics and inspect further to see if I can see any issues.

How important is the B-screw? I tightened and loosened it all the way, and it didn't seem to move the derailleur AT ALL... significant?

nicklouse

The b screw is very important as you would know if you had read Parktools.

rubez

nicklouse wrote:

The b screw is very important as you would know if you had read Parktools.

Parktools is great and all, but it doesn't tell you what to do if the B-screw fails entirely to move the body of the derailluer.

In this instance, the mighty reference site has come unstuck.

cooldad

Er because unless you've got something else wrong, it will.
No single human being, or even collective, could be expected to work out every random thing that every random idiot might be doing randomly wrong by not reading the instructions properly in the first place.

supersonic

In that case your derailer is knackered. Or you can use a longer screw. But is not recommended, rear mechs have a max rear cog tooth size.

If it is not parallel then the cage may be bent. Or the frame/hanger.

Chain may have a stiff link.

Process of elimination.

Ouija

What's the B Screw screwing against? There is usually a rotating doohickey that you have to have orientated the right way when attaching the derailleur to the frame or it doesn't work.

And it isn't always clear that the derailleur is moving when tightening the B screw unless your in the Small/small combo and looking at the upper jockey wheels distance from the small ring on the cassette.

And as for there being only one way to set up your gears, that's simply not true. On some of my bikes (usually triples) i set the limit screw for the small ring for better downshifting even though it causes the chain to rub the derailleur cage in the small/small combination as this isn't a combo you should be using anyway. In fact, there are quite a few slightly different setups you can have on your gears depending on what your after.

rubez

I can see screwing and unscrewing opens and closes a bit on the derailleur, but I couldn't see it moving relative to the cassette. Will have another crack at it.

I see 3 other people having the same problem from a quick search.

http://www.bigboxbikes.com/viewtopic.php?f=5&t=443

http://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/proper-way-adjust-b-screw-shimano-rds-885531.html

http://www.cyclechat.net/threads/rear-derailleur-adjustment-screws-problem-help-plz.140426/

I am not alone

BigAl

Seeing as you're an 'old school', rim brakes, rigid forks kind-of-guy, shouldn't you be running it single speed anyway?

I thought gears, suspension and viable brakes were for girls in your upside-down world.

rubez

Yawn, change that record please.

Quotes from around the interwebs.

I switched to an Alivio rear and I can't get enough adjustment out of the b screw. I even put a longer screw in it but once you thread it in so far it starts to come off the end of the hanger tab.

I've been messing with a Shimano Alivio RD, and don't really notice the 'B' screw doing a whole bunch.

It is surprising that the B screw of an Alivio rear mech needs to be fully engaged to clear the sprockets

Maybe this Alivio derailleur has a problem, or a certain characteristic about the B-screw.

BigAl

rubez wrote:

Maybe this Alivio derailleur has a problem, or a certain characteristic about the B-screw.

Yes, it's definitely more likely that Shimano, who know a little about producing a rear derailleur, have got the design wrong than you, who knows little (apparently) about any form of bike set-up and maintenance, have made an error.

drlodge

rubez wrote:

The derailleur that is skew-whiffed, is like that upside down, and right way up.

It should run parallel, no?

So, that may be part of the problem, or a symptom...

First job is to fix the problem you already identified.

rubez

BigAl wrote:

rubez wrote:

Maybe this Alivio derailleur has a problem, or a certain characteristic about the B-screw.

Yes, it's definitely more likely that Shimano, who know a little about producing a rear derailleur, have got the design wrong than you, who knows little (apparently) about any form of bike set-up and maintenance, have made an error.

I found 3 separate people on the first page of a google search who have problems with the Alivio's B-screw specifically.

Co-incidental? Unlikely.

All I'm saying is there may be something about the B-screw on this particular derailleur...

Anyway, how likely is that to be the source of the problem.

rubez

drlodge wrote:

First job is to fix the problem you already identified.

What is that? The chain? It looks shaky to my untrained eye, so I thought it may be too long, but comparing it to a supposedly "just right" picture from a guide on the internet, it looks near-identical (in regards the angle at which the derailleur is pulled at, in the 'big-big' configuration)

Looks like this, just about.



Also, the two cogs in new derailleur are big then the last one, so if anything, the chain should be too short, not too long!

drlodge

"The derailleur that is skew-whiffed, is like that upside down, and right way up".

That's what you need to fix ---^

rubez

It isn't flush with the rest of the bike, but it is new and hasn't been used, so ruling out faulty goods, could it be something else?

It can't be adjusted apart from brute force bending, can it?

drlodge

Its probably the rear derailleur hanger that's out of alignment. Take it to your LBS to have it *carefully* put back in alignment - they'll either bend it using the appropriate tool or install a new hanger.

cooldad

I would suggest post a picture, but would not want to inflict feelings of terminal deja vu on other members.

drlodge

cooldad wrote:

I would suggest post a picture, but would not want to inflict feelings of terminal deja vu on other members.

The phrase "flogging a dead horse" springs to mind.

rubez

I said later, when I'm actually in the presence of the bike!

97th choice

rubez wrote:

I said later, when I'm actually in the presence of the bike!

You being in the presence of your bike appears to be whats causing all your problems.