Problems with Rear Mechs

nickcuk

Which screw do I use to adjust my apostrophe position ?

imposter2.0

Pinno wrote:

“Never in the field of bike maintenance was so much pedantry dished out by so many to so few.”

Can I propose a correction, thus: “Never in the field of bike maintenance was so much pedantry dished out to so many by so few.”

pinno

nickcuk wrote:

Which screw do I use to adjust my apostrophe position ?

Lever the damn thing out with a crow bar and reposition it with a hammer.
If there is no need to reposition it, keep it in your back pocket for future forum use.

bikingeveryday

The illustration on a properly cut cable appears to show a Brake Cable which are not used for a rear mech.

pinno

bikingeveryday wrote:

The illustration on a properly cut cable appears to show a Brake Cable which are not used for a rear mech.

And? It's simply to illustrate badly cut cables. It's a stock photo. If you want to get a few gear cables, cut some of them badly, take some pictures and pass them to me then fine. The article took a while to compile.

So, instead of nit picking - please answer this: Did you find the article useful?

Alex99

Pinno wrote:

bikingeveryday wrote:

The illustration on a properly cut cable appears to show a Brake Cable which are not used for a rear mech.

And? It's simply to illustrate badly cut cables. It's a stock photo. If you want to get a few gear cables, cut some of them badly, take some pictures and pass them to me then fine. The article took a while to compile.

So, instead of nit picking - please answer this: Did you find the article useful?

I'm not sure it should be a capital D after a colon.

964cup

Nice job.

Things to consider adding:

Shimano pulleys have “guide pulley” written on the upper pulley and “tension pulley” written on the lower pulley. The writing should face outward when installed.

In addition to the “B” screw, Campagnolo guide pulley distance adjustment uses the “H” screw (not to be confused with the upper limit screw) which works a worm drive on the jockey cage pivot.

When cutting cable outers (brake or gear) it's usual to a) file the resulting cut surface until it's flat and perpendicular to the outer and b) use an appropriate sized pick or an allen key to open up the nylon lining and round out the exit hole. 1.5mm for gears and 2mm for brakes if using allen keys (in each case this is about 0.5mm thicker than the cable itself). This avoids problems with threading cable.

There’s a good deal more one could say about electronic (including eTap) but you may feel you already have enough detail for one article; Shimano also post very comprehensive service instructions to their website (e.g. http://si.shimano.com/#/en/search/Serie ... &type=ROAD for Di2), which include details on installation, maintenance and complete disassembly/re-assembly.

pinno

@964 cup.

Good stuff. I'll probably copy/paste most of that in. Cheers.

Garry H

Good article, even for those of us who've "taken the leap".

pinno

You leaped a sheep?!

SmittyWerb

Had problems swapping some derailleurs and this helped me so much, thank you!

pinno

SmittyWerb wrote:

Had problems swapping some derailleurs and this helped me so much, thank you!

(Wot no grammar pedantry ? :shock: )

You're welcome.

robert88

'glad I found this very useful thread.

laurentian

Just about to change my old Sora rear mech back on to my winter bike that doubles as a summer tourer. (I changed to a MTB rear mech for touring in the summer). Apart from a de-grease and re-lube of the Sora mech that is going back on the bike, anything else I should do before re-fitting?

pinno

Not quite enough detail Laurentian.

I'm presuming both bikes have different chain lengths? A triple on the tourer to a double on the winter bike?
Is the Sora a long cage going on to a double chainset transmission? In which case, that's ok.
If they are the same speed, then, apart form the chain length issue above, you should be fine.

laurentian

Sorry, front rings (double) were left on when I changed to the MTB rear mech and will stay on when I change back - Sora is short cage, will change chain back to original too when I put Sora mech back on. Just wondered if there is anything to do apart from de grease and lube whilst rear mech is off the bike . . .

pinno

laurentian wrote:

Sorry, front rings (double) were left on when I changed to the MTB rear mech and will stay on when I change back - Sora is short cage, will change chain back to original too when I put Sora mech back on. Just wondered if there is anything to do apart from de grease and lube whilst rear mech is off the bike . . .

Nothing else as far as I know.

What's the cassette ratio of the winter bike and the number of teeth on the front chain rings?

laurentian

Pinno wrote:

laurentian wrote:

Sorry, front rings (double) were left on when I changed to the MTB rear mech and will stay on when I change back - Sora is short cage, will change chain back to original too when I put Sora mech back on. Just wondered if there is anything to do apart from de grease and lube whilst rear mech is off the bike . . .

Nothing else as far as I know.

What's the cassette ratio of the winter bike and the number of teeth on the front chain rings?

Apologies for the late reply Pinno. I'm completely comfortable and au fait with the other aspects of the change such as the front rings, chain etc and the set up of the rear mech once on the bike. I was just wondering if there's anything to do to the actual rear mech itself other than degrease/lube prior to fitting it back on the bike. Really appreciate your help thus far

pinno

laurentian wrote:

Pinno wrote:

laurentian wrote:

Sorry, front rings (double) were left on when I changed to the MTB rear mech and will stay on when I change back - Sora is short cage, will change chain back to original too when I put Sora mech back on. Just wondered if there is anything to do apart from de grease and lube whilst rear mech is off the bike . . .

Nothing else as far as I know.

What's the cassette ratio of the winter bike and the number of teeth on the front chain rings?

Apologies for the late reply Pinno. I'm completely comfortable and au fait with the other aspects of the change such as the front rings, chain etc and the set up of the rear mech once on the bike. I was just wondering if there's anything to do to the actual rear mech itself other than degrease/lube prior to fitting it back on the bike. Really appreciate your help thus far

I asked the question about the rest of the set up because the only thing I could think of that would be a problem is a long cage on a transmission that doesn't require it or a short cage that is too short. The optimum cage length assists in crisper gear changes but if you are not fussy, it's not major. There really is nothing that would be potentially catastrophic. so set it up, pedal and get back to me.

laurentian

Ah right - when I say "rear mech" I refer to the whole thing including the cage (long on the one that's on there now and shorth on the original that will be going back on) - once agan, thanks for your help

bompington

Very useful thread, particularly for those of us who need to find out about the latest grammar pedantry issues. (FWIW it's nonsense to suppose that mechs should have an apostrophe, unless you habitually write the singular as mech', and, as it's a contraction, you don't)

As for actual rear mech;s - any clues on what to do with one that is starting to get a bit sticky? Anyone ever actually totally disassembled a Sram mechª?

Or alternatively - don't much fancy shelling out a rather juicy £140 or so for a new Force 1 mech¦, is there any reason why I shouldn't just use any old Sram 11 speed mech®?

pinno

Bompy.

11 speed mech on an 11 speed system is fine.

Sticky? First eliminate other possibilities. Now, I know you commute which takes it's toll on anything ferrous, which I am sure you are more than aware of.

First, detach the cable at the rear mech. See if the mech moves freely (with the tension of the spring in mind) in all it's directions i/e down and across. That should give you an indication of it's movement and whether the stickyness is coming from the mech. If the mech is moving freely, check:

Fraying of the gear cable around the BB
Fraying of the gear cable at the chain stay cable mount - it may not be apparent so put it into 1st gear to asses the cable at the point it may be rubbing in the liner/outer.
Is the transmission needing a good clean?
Is the chain worn out?
Do your sti/ergo levers need lubrication?
If the upper jockey wheel is bunged up and the essential play in it is compromised, it may need cleaning/lubricating.


Do those checks and get back to me. Sticky mechs can be cured. It may be salt and grit getting into the pins of the parallelogram, in which case it's possibly worn out but you can clean it in solvent and re-lube which will keep it going for a while longer. It's rare though.

bompington

Cheers Pinno. Christmas break over (no I wasn't being so lazy as not to get out at all - but not on this bike) so time to go back to the garage.

See if the mech moves freely (with the tension of the spring in mind) in all it's directions i/e down and across.
It does now - petrol & grease
Fraying of the gear cable around the BB
Fraying of the gear cable at the chain stay cable mount - it may not be apparent so put it into 1st gear to asses the cable at the point it may be rubbing in the liner/outer.
Cable looks fine the whole way through
Is the transmission needing a good clean?
Can see my face in it, literally
Is the chain worn out?
Probably not in the 10 minutes and 0 miles since it was fitted ;-)
If the upper jockey wheel is bunged up and the essential play in it is compromised, it may need cleaning/lubricating.
Clean, shiny and running free
Do your sti/ergo levers need lubrication?
All fine.

Basically everything cable-wise is running smooth and free - with the possible exception of the last stretch (the sheathed bit) from the seat stay mount to the mech.
The mech moves freely when not attached but there is palpable friction with the cable on. If I take the outer out of its stops then the cable feels as free as anything running through it: in fact I can't identify any friction anywhere.
So I thought - is it the bend of the cable at this point? It's always looked to me like the outer is a bit long here, forcing the cable into too wide a loop. Could this be the problem?

pinno

bompington wrote:

Cheers Pinno. Christmas break over (no I wasn't being so lazy as not to get out at all - but not on this bike) so time to go back to the garage.

See if the mech moves freely (with the tension of the spring in mind) in all it's directions i/e down and across.
It does now - petrol & grease
Fraying of the gear cable around the BB
Fraying of the gear cable at the chain stay cable mount - it may not be apparent so put it into 1st gear to asses the cable at the point it may be rubbing in the liner/outer.
Cable looks fine the whole way through
Is the transmission needing a good clean?
Can see my face in it, literally
Is the chain worn out?
Probably not in the 10 minutes and 0 miles since it was fitted ;-)
If the upper jockey wheel is bunged up and the essential play in it is compromised, it may need cleaning/lubricating.
Clean, shiny and running free
Do your sti/ergo levers need lubrication?
All fine.

Basically everything cable-wise is running smooth and free - with the possible exception of the last stretch (the sheathed bit) from the seat stay mount to the mech.
The mech moves freely when not attached but there is palpable friction with the cable on. If I take the outer out of its stops then the cable feels as free as anything running through it: in fact I can't identify any friction anywhere.
So I thought - is it the bend of the cable at this point? It's always looked to me like the outer is a bit long here, forcing the cable into too wide a loop. Could this be the problem?

Okay, so you've identified that the source of friction is probably not the mech. I doubt it is because the cable at the chainstay is too long but have a look at a 'standard' loop in the pictures at the beginning of this thread for comparison, you never know.

Why don't you just change the outer cable from the chain stay to mech? When you take the cable out of it's stops, it will of course move but it will all move together, no? It doesn't necessarily isolate a point of any friction between the inner and the outer.
Hang on, did you say 'seat stay'? I'm a bit confused.
With the gear cable inner and outer all in place, can you put some resistance by holding the end in your left hand (the bit that would normally go into the mech bolt clamp and with the other, operate the Sti lever to see what happens?

veronese68

Pinno wrote:

Hang on, did you say 'seat stay'? I'm a bit confused.

Top tube cable routing then down the seat stay? Good idea on bikes that accumulate a lot of muck, I'm pretty sure mine does that.
Bomp, I used Shimano XTR gear cables and they have a long rubber bit that goes over an extended ferrule to keep crud out. I'm sure it helps, although your weather is rather worse than mine I should think.

pinno

Veronese68 wrote:

Pinno wrote:

Hang on, did you say 'seat stay'? I'm a bit confused.

Top tube cable routing then down the seat stay? Good idea on bikes that accumulate a lot of muck, I'm pretty sure mine does that.

Then that cable is pretty long, so needs investigating.

bompington

Pinno wrote:

Veronese68 wrote:

Pinno wrote:

Hang on, did you say 'seat stay'? I'm a bit confused.

Top tube cable routing then down the seat stay? Good idea on bikes that accumulate a lot of muck, I'm pretty sure mine does that.

Then that cable is pretty long, so needs investigating.

Yep.


Notice how sharply the cable bends coming out of the seat stay stop: there's also a noticeable angle where it comes out of the guide and heads to the clamp (this pic no good as it's Ultegra - mine's SRAM Force). By now I'm fairly sure the problem's somewhere in there.

pinno

I think I agree with you there. It also looks like the seat stay nipple given it's orientation, is inviting ingress.

veronese68

Pinno wrote:

I think I agree with you there. It also looks like the seat stay nipple given it's orientation, is inviting ingress.

Similar set up on the Pro6 then. The one in this picture has a long length of outer on the bottom loop, excessively long in my opinion.

I doubt I'll see mine to get a picture in the next few days, but that long rubber bit seems to do a good job of keeping moisture out. My bike is nearly always kept under cover at home and at work which may help.

pinno

Long cable shouldn't be a problem - at least there are no kinks in it, unlike you.