Problems with Rear Mechs

keef66

Guigu wrote:

It was the actual derailleur, I ended up updating to uktegra 6800 as a treat to myself.

Thanks for your help

I'm thinking your 6800 RD may not work well with 6700 levers because Shimano changed the pull ratios when they moved from 10 to 11 speed.

pinno

keef66 wrote:

Guigu wrote:

It was the actual derailleur, I ended up updating to uktegra 6800 as a treat to myself.

Thanks for your help

I'm thinking your 6800 RD may not work well with 6700 levers because Shimano changed the pull ratios when they moved from 10 to 11 speed.

Maybe he hasn't rode it yet.

StillGoing

DougalG wrote:

Hi! I’ve just bought an s-works sl6 disc. Great bike ...

There is however something strange about the Di2 gear shifting : I cannot use all 22 gears.

Now the bike shop tells me that this is no surprise because the disc causes the wheel to be wider and as a consequence not all gears can be ‘reached’. In fact, 6 of the gears cannot be used. As a single example the 2 smallest gears at the rear cannot be driven by the smallest front gear/sprocket.

Does anyone have any experience of this??

Dougal

Di2 isn't designed to let you use all 22 gear options. The rear derailleur when in the inner ring, is designed to stop you using the smallest 3/4 sprockets on the cassette. When in the big ring, it will stop you using the biggest sprocket. This is all to protect the rear derailleur, avoid cross chaining where you lose watts and to maintain the best gear ratio combination.

trickytree1984

I'm in the process of fitting Di2 6870 to my winter bike. The groups set was taken off my summer bike which got written off. So far so good, but it turns out that the rear mech cage (long) is bent. Everything else functions fine (not ridden yet but looks good on the stand).

Now i have a spare 6800 mechanical rear mech (short). Can I take the cage off a 6800 short cage mech and fit to a 6070 long cage mech?. Id rather run it short anyway as i only have a 28 cassette on the back.

Thanks

radhartgeorge

Hoping for some help identifying why with my Ultegra Di2 shifting down the cassette (into harder gears) would index perfectly fine, but shifting back up would result in poor indexing? I end up having to go into gears two above what I want then shift down one. Anyone else suffered this and found a solution?

pinno

Sorry George(?), Di2 not my thing. Post your query in Workshop.

drhaggis

Hi,

I suspect the jockey wheels on my Tiagra 4700 rear mech are shot. The lower (tension?) wheel has almost no teeth whatsoever, and, even after disassembly, cleaning, and applying some grease, the upper guide wheel isn't really rotating freely, so I suspect the bearings might be shot. Two questions:

1) This DR is slightly bent after a crash in which a taxi took me out without giving way. Is it worth it to spend ~£10 on the jockey wheels instead of £25-30 on the whole DR?

2) Which jockey wheels should I buy in this case? "Tiagra jockey wheels" doesn't return anything useful on Wiggle...



PS: I don't know how so much crap got stuck to the chain in 30 miles...

keef66

My 105 RD went the same way. It felt slightly wrong, but in the end it made no sense just replacing the jockey wheels when I could get an entire new mech with lovely corrosion free pivots / bearings / bushings / screws and springs for not much more.

The bloke in the garage where I first worked always preferred replacing components before trying to fix them. He'd always cheerily say "it doesn't pay to get involved". When time was money he did have a point, and he'd always fix the problem first time.
In his own time though he was an inveterate tinkerer, once famously inserting a 911 engine into a beetle just to see if he could

riceaway

Besides wear on the idler pulley's on the rear derailleur causing problems, on Campy equipped bikes there is a problem with wear on the ratchet mechanism for the right lever.

If you find that when you shift cogs that going up they will hold the proper gear or going down they will but shifting from the opposite direction they don't, replacing the idler pulleys and the front ratchet mechanism is in order. Campy only makes spare parts on the mechanisms they are selling at the time but there are still spare 9 and 10 speed partial mechanisms available from dealers or off of the Ebay groups. This requires you to replace the large shift lever from your present lever onto the new mechanism and to replace the hood. The hoods are a bit tricky and if they are not properly placed it feels like there's something wrong with the shifters. So be certainly that all of the hood locking nubs are correctly in their matching holes. In some cases you might wish to replace worn hoods as well. Although expensive you can get everything in parts and assemble them for half the price of buying a new lever. And these new levers are extremely limited in numbers.

The idler pulleys are normally worn from excessive chain wear so you always have to be careful to replace your chains on schedule. There are roller bearing idler pulley's that work better than the plain bearing ones and from China are cheaper than the Campy parts. Be sure and buy the 11 tooth models.

Shimano in general doesn't make or distribute spare parts. But their ratchet mechanisms do not appear to wear in the same manner and much slower as well. And all but DuraAce components seem to be so cheap that it isn't worth messing about with them.

Some people like the single gear shifting of SRAM but I only have passing experience with them.

neeb

So I have a weird issue with an 11sp Campagnolo Record rear mech (post-2015 but pre-HO).

I don't use a torque wrench to fix it to the hanger (because I've never managed to find a T25 bit that fits into that recessed hole where the bolt is), but I'm sure that the problem arises before the torque is anywhere near the maximum 10-12 Nm.

Basically, fastening the mech to the hanger with any substrantial torque seems to make the spring mechanism on the top pivot sieze up.. If I want it to move freely I have to torque it up relatively gently. Even more oddly, the shifting is actually better when this pivot is a little stiff, although obviously if it's too stiff then the chain is slack inthe small sproclet / small ring combo.

What's going on here? I assume it must be some fault with the top pivot / fastening bolt apparatus?

pinno

Have you removed it multiple times for some reason?
I think it's simply a spring issue and a little bit of play. The spring is no longer able to overcome the friction created by screwing in to the hanger. There seems to be too much play in the plates that retain the spring which is upping the friction.

There: https://www.ebay.co.uk/itm/Park-Tool-PH ... Sw69tcLxN8

You don't need a torque wrench - go by feel. 12nm is not a lot and you should have a rough idea as to the torque required from other applications.
I use Torque wrenches on cars but never have felt the need to use one on a bike* and I have snapped only 1 face plate for a gorgeous Colnago engraved stem in 33 years of fettling. that was only because I failed to evenly tighten the 4 bolts (@4nm), Tired and in too much of a hurry.

*The exception being the 46 to 52nm tightening torque on Campag Ultra torque chainset connecting bolts. Incidentally, I have always tightened them to the lower 46nm and they have never loosened.

For a more definitive answer, pm thecycleclinic or email: workshop@thecycleclinic.co.uk

They are Campag guys through and through. I got my replacement. single unit bearings for my Eurus wheels from them.

neeb

Thanks. I already have one of those tools!

Yes, I've taken the mech on and off quite a lot. I'm an inveterate fettler. always swapping groupsets between frames, building up new frames etc.

*The exception being the 46 to 52nm tightening torque on Campag Ultra torque chainset connecting bolts. Incidentally, I have always tightened them to the lower 46nm and they have never loosened.

Ha ha, I always torque them to the higher number, it must be a personality thing.. I'm the kind of person that can never resist adding a little more, it's borderline obsessive compulsive. I always torque the rear mech cable holder to about 6.1 - 6.2 Nm rather than 6.. I figure that if it specifies 6 exactly there must be a big enough margin of error built in for me to get away with 6.2 and then it's definitely not going to slip..

The problem I find with torque and feel is that a given torque only feels the same if the lever length and type of handle is the same - I know what 10 Nm feels like on my torque wrrench, but not when using the centre-grip handle on that T25..

I've also sometimes experimented with using the bolt on the other side to install and/or remove it, maybe that's screwed something up?

I think it's simply a spring issue and a little bit of play. The spring is no longer able to overcome the friction created by screwing in to the hanger. There seems to be too much play in the plates that retain the spring which is upping the friction.

I can't quite create a mental image of that - perhaps because I don't know what that particular pivot looks like inside (It has a really complicated c-clip that's apparently designed to be difficult to remove..).

pinno

I figure that if it specifies 6 exactly there must be a big enough margin of error built in for me to get away with 6.2 and then it's definitely not going to slip.. [/quote]

Consider that if your torque wrench is 10% out (very few torque wrenches are accurate to within + or - 3%). Your 6.1 nm could easily be 6.7 or even 5.5nm. 5.5 nm would probably safely do the job.
My friend lent me a torque wrench for some balance shaft bolts on an engine I rebuilt.
The reason was that my mid range 25nm to 80nm had died and I needed to borrow one in a hurry whilst I sourced a replacement. I have one up to 28nm and I have another for between 40nm and 210nm.
The bolts in question were 33nm.
His wrench went from 25nm to 120nm. I stripped the aperture of one of 4 bolts tightening to 33nm in sequence.
When I got the replacement, I slowly set the 12 to 120nm wrench to 33nm from 20nm in 2nm increments to undo the other 3 bolts which were in still in situ. The 'un'-tightening torque was IRO 41nm ! I re-tapped the aperture to an M10 from an M8.

I then got a some bits out of the scrap box and set about trying to compare tightening torques between the 4 wrenches.
It became pretty apparent that in the lower and upper 10% of each wrench, they were slightly inaccurate. Or at least, the tightening torque varied immensely but I had no means of actually testing what each torque wrench was doing and I had no means of cross referring the lower limits of the low range TW and the upper limits of the bigger 40 to 210nm TW.

The conclusion that I drew is not to trust that just because a torque wrench is set to 10nm that it is going to deliver 10nm. Therefore, erring on the side of caution that it may be over tightening is probably prudent.
I hope that my new certificated (mid range) Teng tools wrench is spot on.
In a bolt that you tighten to 4nm, a 10% variable is probably far more critical than a bolt that you tighten to 80nm.

Back OT:
You are a bit obsessive, you have removed the rear mech many times and you have worn out something.

neeb

Oh yes, I'm not claiming that my appoach is entirely rational .. That said, I've never caused problems by overtorquing anything (except once, a long time ago, stem bolts on a carbobn stem that was unevenly supported internally by a short bung.. That taught me a valuable lesson about blindly trusting numbers on a torque wrench..).

I have a Norbar torque wrench which (as I understood when I bought it at least) is very good. That said, it's probably about time a got it calibrated..

pinno

Any follow up to this Neeb?

cycleclinic

I dont think I have ever used a torque wrench to do up the bolt on a RD. I just tighten it. Mechanics just know. So it could be as simple as a over tightneing. The fact you can get it to work properly indicates there is nothing wrong probably. 10 Nm is nothing.

neeb

Pinno wrote:

Any follow up to this Neeb?

I ended up just buying a new HO rear mech. Keen to stock up on 11sp stuff anyway as 12sp doesn't do anything for me..

The new mech doesn't sieze up when torqued on and shifts much better, confirming (if there was any doubt) that the upper pivot on the old one is knackered.

I'd still like to get it working again though. From the spare parts diagrams I would probably need RD-SR006 and/or RD-SR109, But these parts are "service centre only" and the pivot looks tricky to disassemble.. I assume that the cost of out-of-warranty repair wouldn't be worth the 2nd hand value of the mech..

neeb

thecycleclinic wrote:

I dont think I have ever used a torque wrench to do up the bolt on a RD. I just tighten it. Mechanics just know. So it could be as simple as a over tightneing. The fact you can get it to work properly indicates there is nothing wrong probably. 10 Nm is nothing.

It's possible that I've damaged the mech at some point by overtorquing the bolt, but the seizing up thing is definitely not just from it being torqued on too tight. It begins to stiffen up slightly with just the slightest torque applied after the bolt is all of the way in, and gets progressively stiffer as it's tightened further.

pinno

neeb wrote:

...confirming (if there was any doubt) that the upper pivot on the old one is knackered.

I told ya

drhaggis

DrHaggis wrote:

Hi,

I suspect the jockey wheels on my Tiagra 4700 rear mech are shot. The lower (tension?) wheel has almost no teeth whatsoever, and, even after disassembly, cleaning, and applying some grease, the upper guide wheel isn't really rotating freely, so I suspect the bearings might be shot. Two questions:

1) This DR is slightly bent after a crash in which a taxi took me out without giving way. Is it worth it to spend ~£10 on the jockey wheels instead of £25-30 on the whole DR?

2) Which jockey wheels should I buy in this case? "Tiagra jockey wheels" doesn't return anything useful on Wiggle...

So in the end I didn't do anything (professional procrastinator). But it turns out my bike, now fully serviced, about 6 weeks ago and with a new chain, makes some horrendous noise when on the big ring and on the smaller cogs (12, 14 & 16T). The ride is silent on the 11T, mind you. Because this only happens on these cogs, and even shortly after lubricating the chain and cleaning the cassette, I suspect it's the jockey wheels causing issues. Does this make any sense?

If it does, how would I try to lubricate the jockey wheels? Grease? Chain lube (I use squirt)?

pinno

Jockey wheels comprise of 2 outer 'cups' and a hollow axle.



Some, like the Record 11, have a sealed bearing.
You can buy Replacements which have sealed bearings:



It is easy to dismantle them. To save getting in a tangle, remove the chain.
Clean both jockey wheels and parts. Re grease and then re-assemble.
Make sure that the jockey wheel with play in it goes uppermost as this is critical to a smooth gear change.

Before you do that, is your chain rubbing on the front mech by any chance?

drhaggis

Pinno wrote:

Before you do that, is your chain rubbing on the front mech by any chance?

Thanks for the answer Pinno! I can't fully discard chain rubbing. However... why would the chain rub in intermediate cogs (12, 14, 16) but _not_ on 11?

pinno

Badly adjusted front mech.
The cage of the front mech should sit perfectly parallel with the chain:



A and B is wrong, C is correct.

Have you got a workstand? If not, get someone to hold up the back wheel and see what the chain is doing in the above gears when pedalling or failing that assistance, turn the bike upside down old school. (Put cloths on the floor to protect the saddle and the stem).
Back pedalling with the bike upright may elicit the right conditions to create the noise but it may not.

It should be reasonably easy to ascertain squeaks from rubbing.

paul64

Really useful thread and appreciate the time that went into it. If it hasn't already been mentioned you occasionally hear of someone scratching their head at poor gear changes when trying 'everything' and the tightening of a quick release has affected the angle of the rear derailleur, might be worth adding to the final warning.

ultimedia

Hi all,

A few weeks ago I was in an unfortunate crash when a few riders fell right in front of me, my rear derailleur, derailleur hanger and rear wheel all got serious beating resulting in a necessary replacement of all three.

I’ve currently replaced the components and I’m encountering the following problem: there is a “one sprocket” offset on the rear casette. This results in a dropping chain if I shift to the smallest sprocket and doesn’t allow me to shift to the largest sprocket.
I’ve adjusted the limiter screws in every possible way but this doesn’t make any noticeable impact. Apart from this issue, the shifting itself is flawless, it probably looks like an easy problem to fix, I checked some videos but can’t find a solution for this specific problem.

Any tips / advice? Thanks!

pinno

Please explain 'the one sprocket offset'.
It's not going down to the smallest cog on the cassette?
What rear mech (shimano, campag...)?
What speed, (8, 9, 10...)?

ultimedia

Pinno wrote:

Please explain 'the one sprocket offset'.
It's not going down to the smallest cog on the cassette?
What rear mech (shimano, campag...)?
What speed, (8, 9, 10...)?

Hi,

It's a 10Speed Shimano Ultegra group.

With the one sprocket offset I mean that it's not going on the biggest cog on the casette but always gets dropped on the other side (smallest cog).

webboo

Have you got the spacer on the hub.

mankybianchi

Ultimedia wrote:

Pinno wrote:

Please explain 'the one sprocket offset'.
It's not going down to the smallest cog on the cassette?
What rear mech (shimano, campag...)?
What speed, (8, 9, 10...)?

Hi,

It's a 10Speed Shimano Ultegra group.

With the one sprocket offset I mean that it's not going on the biggest cog on the casette but always gets dropped on the other side (smallest cog).

Sounds like the stops are not set correctly.

Start from scratch with cable to rear mech disconnected, chain on smallest sprocket and set the high stop. If when rotating the cranks causes the chain to fall off then the stop is set too far out. You can also check by looking from the rear of the bike to see if the top hockey wheel is sitting nicely in line underneath the sprocket.

Once this is set correctly, reconnect the cable and shift only to the next sprocket.. If it doesn't quite make it, shift the lever back to its previous position and then tighten the tension and try again. If it overshot the sprocket then, as above, move lever to previous position and slacken the tension.

Follow the routine up the cassette - shift to next large sprocket then back down 1 again adjusting for over or under shifting.

By now if you can't shift into the largest sprocket it will be due to the low stop set too far in. Turn the low screw anti-clockwise half a turn at a time until you can make the shift.

pinno

Webboo wrote:

Have you got the spacer on the hub.

This ^ and is your cable tension wrong?