So, this might have happened... NBD - 2016 Fuji Touring workhorse

[wafter]

Today the Fuji was unceremoniously inverted so that I could try and get some dims off its drivetrain for other endeavours..

During this process I noticed that the bottom of the rear derailleur cage was really canted outboard relative to the rear wheel. The cage is also bent at the lowest, inner edge near the bottom idler pulley; suggesting that it might have had an impact in the past (although I don't recall owt in my ownership that could have caused this).

A look at the back end of the Genesis for comparison suggested that the cage should be vertical relative to the bike, so I gingerly bent back the Fuji's RD while ensuring that the apparently straight hanger remained that way.

After this brutality shifting onto smaller sprockets appeared a bit sluggish; the top idler pulley seemed conspicuously close to the sprockets so the B-screw was given a turn in to give a bit more clearance. Shifting improved but there was also some oscillation felt through the pedal (when turning by hand at speed) on the middle-ring-to-smallest-sprocket 36/11 combination.

Tweaking the limit screw out a bit didn't seem to help much, however on a subsequent short, chilly test ride around the village the bike seemed as unfussy and quiet as I've come to expect; with no obvious complaints even when running 36/11.

While technically not ideal, one of the things I love about the 3x9 setup on this bike is the fact I can run the middle ring on the front pretty much 99% of the time while using the full 11-34t range of the cassette without any obvious problems.

I'm hoping that stumbling upon, and hopefully addressing this issue with the cage will finally sort the ghost shifting issue I've always had with the bike; and I plan to setup and test the indexed shifting the next time circumstances allow.

I've also adjusted / tightened the mudguards, which hopefully has resolved another of the little niggles that's been irritating me for months...

No pics of the "work", but here's one from yesterday's foggy excursion

 

[All uphill]

Can you borrow a chain alignment tool?

I use 3 x 9 drivetrains and find that the hanger needs to be better aligned in both axes than can be achieved by eye.

As for the rd itself I've a spare known good one I'm happy to lend you, if that helps.

 

[wafter]

Can you borrow a chain alignment tool?

I use 3 x 9 drivetrains and find that the hanger needs to be better aligned in both axes than can be achieved by eye.

As for the rd itself I've a spare known good one I'm happy to lend you, if that helps.

Thanks - appreciate the offer!

I do have a hanger tool and it has been used on this bike; suggesting that there was nothing significant amiss. That said it's a cheap one and a bit sloppy, while the paint is chapped on the mounting face so it doesn't provide a very good register face for the tool.. as such that escapade wasn't entirely conclusive.

Whatever misalignment may have been / still be present has to be a lot less compared to he deflection in the RD though; I couldn't measure it as there was no convenient datum but it was probably out by 5-10mm across its length.

It seems a bit weird for the RD to sustain damage on its inside / be forced to deflect outwards - the bike's had a new / rebuilt rear wheel so I wonder if it was involved in a fairly significant accident at some point.. Thankfully there's no obvious damage on the frame to corroborate this although I've not checked it all for alignment..

 

[Gunk]

We often encounter a few issues like this at work. As you have suggested, firstly make sure the hanger is straight, however if the mech itself has taken a whack they’re sometimes difficult to straighten, if after fettling it’s still not shifting properly, we tend to just swap them out for a good used one, it usually solves the problem.

also we use a bit of loctite on the fastenings for the mudguards, it stops them rattling loose.

 

[wafter]

We often encounter a few issues like this at work. As you have suggested, firstly make sure the hanger is straight, however if the mech itself has taken a whack they’re sometimes difficult to straighten, if after fettling it’s still not shifting properly, we tend to just swap them out for a good used one, it usually solves the problem.

also we use a bit of loctite on the fastenings for the mudguards, it stops them rattling loose.

Thanks - I was considering a new RD. The current RD-M591 is discontinued although they seem to come up regularly used on ebay. Failing that there seem to be plenty of decent budget long-cage offerings from Shimano which I assume will work.

I did briefly consider fitting the slightly-cosmetically-damaged GRX item from my Genesis and replacing that with a new one since I've seen them reduced in a few places. That said they're still not cheap, the 11sp road-based cable pull is probably significantly different to that for the 9sp MTB bits currently fitted and I have to keep reminding myself not to keep throwing money at what's supposed to be a budget utility hack.

I think the sitution with the guards is more due to the stays / guards themselves getting a bit bent during use; while the bolt on the fork crown's fitted with a nyloc nut so in theory shouldn't be going anywhere; rightly or wrongly I assumed various bits (like the plastic spacer fitted) have just taken a bit of a compression set over time. If the problem persists I'll consider a dab of thread lock however

Since I evidently can't face any more critical tasks today I'm gearing myself up for a waft down to the farm for some eggs; so will engage the indexing function on the rear shifter, chuck an Allen key in my pocket and see how terrible the shifting remains

 

[wafter]

Inevitably my hopes proved to be unfounded and the indexing problem persists. It's almost like the cable-pull ratios are mismatched.. today all seemed good to start with, however on the smaller sprockets there was a tendency to creep up to the next largest sprocket.

Releasing some cable tension on the RD prevented this happening but also served to push the problem to a different part of the cassette; causing one sprocket to be jumped when shifting sequentially from the largest towards the centre of the cassette.

I can't see how anything becoming damaged on the RD could affect this (which has remained very consistent in its performance throughout all of my interference) and to the best of my knowledge the Microshift shifter is the correct 9sp item - this standard being the last where pretty much everything (road, MTB..) was compatible.

Meh, back to friction shifting it is; at least it was nice to get out for a bit.

 

[Jameshow]

Inevitably my hopes proved to be unfounded and the indexing problem persists. It's almost like the cable-pull ratios are mismatched.. today all seemed good to start with, however on the smaller sprockets there was a tendency to creep up to the next largest sprocket.

Releasing some cable tension on the RD prevented this happening but also served to push the problem to a different part of the cassette; causing one sprocket to be jumped when shifting sequentially from the largest towards the centre of the cassette.

I can't see how anything becoming damaged on the RD could affect this (which has remained very consistent in its performance throughout all of my interference) and to the best of my knowledge the Microshift shifter is the correct 9sp item - this standard being the last where pretty much everything (road, MTB..) was compatible.

Meh, back to friction shifting it is; at least it was nice to get out for a bit.

Tell us the rd / shifter combination and I'm sure we can advise further....

 

[Gunk]

however on the smaller sprockets there was a tendency to creep up to the next largest sprocket.

Cable too tight?

 

[Brandane]

Cable too tight?

Or cable inner/outer gunged up or rusted, causing the problem in smaller sprockets but not on the larger ones where additional cable tension disguises the issue? (I haven't read the whole thread so not sure if cables, inner and outer, have been replaced).

 

[Gunk]

Or cable inner/outer gunged up or rusted, causing the problem in smaller sprockets but not on the larger ones where additional cable tension disguises the issue?

Good shout

 

[wafter]

Thanks all; appreciate the thoughts although I think this has been discussed previously in this thread and we're probably going round in circles..

Tell us the rd / shifter combination and I'm sure we can advise further....

It's a Microshift 9sp shifter, Deore M591 RD and Shimano HG400 cassette; all of which is original-fitment and should on paper work together.

Or cable inner/outer gunged up or rusted, causing the problem in smaller sprockets but not on the larger ones where additional cable tension disguises the issue? (I haven't read the whole thread so not sure if cables, inner and outer, have been replaced).

Yup; it had new inner / outer rear shifter cables some time after I got it, and the problem has persisted, unaffected since I first got the bike so I don't think it's owt to do with the cables.

Granted the cables take a fairly convoluted route so friction between inner and outer could be a factor, however I don't think the fault is consistant with this.

Presumably a cable issue would result in the cable being reluctant to shift; likely most obviously on shifts to smaller sprockets since it's only under the action of the return spring rather than the force being applied to the lever. While this fits once half of the problem (the prepensity to shift into a larger sprocket unannounced) this runs counter to the other problem encountered when cable tension is adjusted to try and resolve this - i.e. the chain jumping two sprockets on both up-shifts and down-shifts.

It's like the pull ratio is varying throughout the shifter / derailleur's stroke; although I can't see how unless something has been manufactured wrongly or is perhaps excessively worn; although I'd expect the latter to give consistantly bad results. There is some free-play in the shifter so perhaps that could be responsible; although I don't think the bike's seen than much use depite its sorry state when acquired (it was still on original chain and tyres when I bought it).

There does seem to be quite a lot of stuff online regarding shifting issues with these particular shifters; so perhaps it's a design issue..?

 

[All uphill]

I had a similar issue with my round town bike, also 3 x 9.I did the alignment stuff, checked chain, swapped derailleur, new cables and finally solved the problem by swapping the nearly new Microshift cassette for a new Shimano one.

Looking at the microshift cassette revealed that it had rounded edges to the ramps that help shifting. The new one had crisp edges.

 

[wafter]

I had a similar issue with my round town bike, also 3 x 9.I did the alignment stuff, checked chain, swapped derailleur, new cables and finally solved the problem by swapping the nearly new Microshift cassette for a new Shimano one.

Looking at the microshift cassette revealed that it had rounded edges to the ramps that help shifting. The new one had crisp edges.

Thanks - I do have a replacement cassette but I don't think this is the problem as the shifting issue migrates up and down the cassette with cable tension adjustment.

I suppose it wouldn't be a bad idea to try to quantify the amount of RD displacement with every indexed shift; although I suspect this might be easier said than done..

 

[wafter]

Tonight I've mostly been measuring.

Thoughts of the RD and cable pull ratios had brought me back to the workable but evidently less than ideal situation wth the brakes; which exhibit a fair bit of lever travel, are somewhat mushy, require precise setup and only allow limted adjustment with the barrel adjustors I fitted some time ago.

According to the fantastic, perpetually informative Bike Gremlin site the amount of cable "pulled" by brake levers differs for various types of brakes. Apparently for 20 degrees of lever travel, levers for traditional road calipers pull around 7mm length of cable ("short pull"), the SLR road standard pulls 8mm and levers intended for use with full-size V-brakes pull 15mm ("long pull"). It's commonly suggested that the nebulously-named mini-V-brakes work with the 7/8mm "short pull" road standard of brake lever...

The TRP RRL levers on the Fuji are described as being compatable with "short pull" road calipers. I measured the effective distance / lever arm from the brake lever's main pivot to the point at which the brake cable attaches at 20mm. Using the relationship between a circle's diameter and circumference tells us that 20 degrees of lever travel would pull almost exactly 7mm of cable at a 20mm radius.. so their stated compatability seems correct.

The brake levers have an effective length of around 55mm from the deepest part of their curved contact surface with the hand and their main pivot; giving a ratio of around 2.7:1 between the displacement applied at the brake lever and the corresponding length of cable pulled - i.e pulling the lever 27mm at its centre would pull around 10mm of cable...

Below is the lever in bits - the cable attaches via the silver bush near the top of the lever:

Next I had a look at the seemingly "mini" V-brakes. Apparently full-size V-brakes have an (effective?) arm length of maybe 100-107mm and require appropriate "long pull" brake levers. The arms on mine measured 91mm so I suppose are about halfway to / arguably close to the poorly-defined mini standard of 85-90mm.

The brake arm length is only half the story however - the other being the position of the brake pads; which can move significantly along the length of the arm to suit wheel size and brake mounting position. This will alter the ratio between the displacement at the end of the lever where the cable is mounted and the brake pad; nd hence the system behaviour as a whole.

My pads are around 34mm from the pivot, giving a ratio of around 2.7:1 relative to the point at which the cable is anchored.

The upshot of all this is that the combined ratio of the lever and V-brakes is around 7.4:1; meaning that for a given lever pull the displacement of the brake pads is 7.4 times less and the applied force 7.4 times more.


Here's a picture of the brakes to make it the post look less like a bland block of text and incentivise you at least reading a bit more. If you made it this far have a biscuit.

For comparison I took some measurements from the brakes on the Brompton since it's the only bike I currently have access to that has caliper brakes. The brake lever had an effective length of 70mm and 25mm lever arm at the cable mount for a cable pull of around 8.75mm per 20 degrees of lever travel and pull ratio of around 2.8:1, so similar to that of the Fuji.

Conversely the dual-pivot caliper have a ratio of around 1:1 - meaning that the combined displacement of the pads is about the same as the amount of cable displacement to actuate the caliper. This is significantly less than that of the Fuji's brakes and the total system pull ratios of 7.4 for the Fuji's brakes and 2.8 for the Brompton suggest that the latter bike's brakes require about 2.6 times less lever travel for a given amount of brake pad displacement, and exerts 2.6 times less force at the brake pad for a given force at the lever.

Assuming the Brompton calipers are broadly representative of typical road calipers, this would explain why the Fuji's brakes behave as they do. It also highlights how, while mini V-brakes are supposed to be compatable with road levers, in reality they're just about a workable solution that "work" at the cost of excessive lever travel.

Unfortunately there doesn't appear to be much I can do to resolve this situation. Brakes with shorter arms would help, however there's only about 5mm clearance between the mudguard and cable assy so such a small change (assuming I could find something of a suitable size) would only bring limited benefit.

Apparently cantilever brakes use the same cable pull as standard road stuff (whether this is a somewhat liberal interpretation of "same" as with the mini-Vs in uncertain), however they apparently don't have a great rep - possibly because their lower pull ratio means more force is needed at the lever for a given force at the pad - making them harder work...

Anyway, I think that's enough for tonight. A somewhat irritating conclusion reached but it's nice to properly understand / nail some numbers onto one more facet of the bike

 

[wafter]

More trivial adventures today..

Yesteday saw the removal of the crankset to inspect the BB cups after some suspicious clicking; reminding me of the corrosion present inside the crank's Hollowtech axle. This was attacked by plugging one end with blu-tac, filling with white vinegar and leaving it preciously propped up on bits of wood. After maybe 6-8hrs with a few cycles of draining, inspection, scrubbing and refilling (with the same solution) the bore looked much cleaner.

I could have left it longer but it appears to be plated (I'd guess Nickel); which was obviously already damaged in the areas of corrosion and from the effervescence wasn't playing so well with the vinegar so I wanted to minimise exposure. I must have a go at making some council evaporust as that should be kinder to adjacent metal..

Earlier a rummage in the shed turned up an untouched can of waxoyl. After the rusty lid was removed using paraffin and brutality, the contents transpired to have separated somewhat. It appears that the heavier components had crystallised out during ten years in the cold shed; leaving something visually akin to a fine chunks of caramel floating in a light treacle sauce; if less tasty.

This was remedied by sticking the whole can on the hob on a low heat for an hour or so, while I did other stuff in the kitchen to ensure I'd be there to enjoy the full experience were it to catch fire..

In the meantime the chainwheel end of the crank had been haphazardly shuttered off with a card disc and masking tape. Once dessert was again nice and homogenous, an amout was poured into the axle and sloshed around to coat the inside. Unfortunately it solidified pretty quickly on contact with the axle, which had to be heated up with a hot air gun to get the waxoyl flowing again.

Finally the axle was held with the open end over the waxoyl can and heated to allow the excess to run back into the can. At this point I took the opportunity to use the airflow through the axle to apply a liberal amount of waxoyl to the surroundng work surface, floor and my person..

The crank's now back on the bike and hopefully further corrision no longer a concern. Time will tell if the wax becomes a problem in the heat of the summer..