7/8s Shimano STIs; not quite so horrifying inside after all

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Brucey
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7/8s Shimano STIs; not quite so horrifying inside after all

Postby Brucey » 26 Aug 2018, 11:51pm

I have to say that I am still not convinced by STIs even after all these years (about 26 now.... :shock: :shock: ). I still think they are overly complicated, vulnerable to damage, hideously expensive (often the single most expensive part after the frameset), heavier and not so comfortable to use as you might expect.

They are also inflexible in use; they don't have a friction mode (unlike previous incarnations of indexed shifting), and they narrow your choices of derailleurs, sprockets etc and brakes to a small fraction of all those available; a kind of self-imposed tyranny if you like, since very many riders wouldn't consider buying a dropped handlebar bike without them, even though I'd describe them as contributing to a 'marginal gain' rather than transforming the way you ride. [In my mind I have a special place in hades reserved for the person that thought that indexed front shifting was a good idea; the amount of time wasted on this particular item is almost unbelieveable....]

I quite happily ride most of my bikes without such things fitted, and I think they are particularly inappropriate on touring bikes (if they are damaged or go faulty your trip is ruined unless you have the foresight to carry a spare DT lever or something) and probably the combination of more widely spaced gearing and (hopefully) a 'no hurry' attitude makes them of lesser value anyway; at best a convenience whilst they are working, and only then if you are happy to ride on the hoods most of the time.

However I will grudgingly admit that whilst shimano have dropped a clanger with some models that break way too easily (eg ST-5600 left shifters; have you tried finding one of those in GWO...? They appear to have all broken...shimano quickly launched the ST-5601 model, which may be their way of saying 'sorry guys we screwed up' :roll: :roll: .) there are others which (crash damage asides) seem to survive much longer than I originally expected. These include models ST-7400, ST6400, ST-A550 (RX100), ST1055, ST1055-T, ST-A410 (RSX 3x7), ST-A416(RSX 3x8)

I think shimano went slightly overboard with these 7/8s shifters, for fear that they might make something where the marginal gain wasn't seen to be worth any lack of robustness or durability. This family of shifters share many parts as well as a similar architecture. The subsequent 9s shifters were built slightly differently inside and most 10s/11s models owe very little to this layout. The 7400 and 6400 models have decals over the front bolt, but underneath they are very similar to the others listed above, eg.

http://bernd.sluka.de/Fahrrad/Shimano/TM/ST-1055_1996.gif

[NB It isn't a bad idea if you have the above open in another window; I shall refer to some parts by number as per that illustration later on.]

However, nothing lasts forever; eventually these shifters may wear, be damaged, or simply stop working so well, typically because the lube has dried out inside or water has penetrated the workings. Besides 'buying another one' there are basically two approaches that are commonly mentioned in the same breath as 'faulty/sticky/erratic shimano STI';

- squirt some lube in the workings (and hope) or
- disassemble the shifter and overhaul it properly.

One is fairly well dissuaded from the latter by photos like this;
Image
https://sheldonbrown.com/sti-repair.html
which (probably rightly) portrays the latter as being too complicated for your average DIY mechanic; one imagines that if you open the STI up, those of a weak disposition will begin to weep, birds will fall from the sky, crops will fail, and sensitive ladies will fall down in a dead faint etc. [I daresay if Bateman were still alive, he'd have done a "the man who suggested taking an STI apart" cartoon... :wink: ] .

However I think there is a third method that is worth a go. In this post I shall describe/link to each of the three methods.

a) External lubing. This has the great advantage that it is fairly fast/easy and may cure the problem. If you squirt a penetrating lube (GT85 or WD40) into a sticky shifter (through any and all openings in the shifter mechansim) and 'exercise it', a faulty shifter will often miraculously recover. It isn't a bad idea to cover or remove the hood first, because many lubes will contaminate and degrade rubber parts. Having restored the function this way, it is a good idea to follow up the penetrating lube with something that will be a better lubricant in the long term, but that won't dry out so easily. An Aerosol SFG (semi fluid grease) is a good choice. The original factory lube appears to have been some kind of white grease, that was never mobile enough to coat the parts properly (so some bushings can corrode) and variously doesn't inhibit corrosion very well, and dries out.

b) if the above treatment doesn't work, I would suggest a frontside inspection next. I recently bought a set of (almost immobile) RSX 3x7 STIs at a bike jumble, with an idea that if they if they didn't succumb to option a), I'd dig in a bit deeper. I was almost disappointed when the shifters appeared to have recovered following the spray lube routine..... but then the RH one (which had been mysteriously a bit more draggy than I'd like) jammed solid. Thus I girded my loins and got stuck in. I got on so well that I did a sceond one too, and this time I took some photos.

Step 1 is to remove the face plate. This is held on by an M6 (typcially) threaded bolt which (if exposed) accepts a 5mm allen key. To get at the same bolt on 7400 and 6400 models, you need to remove the covers, and the bolt beneath is hex headed.

Image01328.jpg
easy does it...

the bolt has a toothy locking washer beneath and the front cover is located so that it cannot turn. Once pulled off, you will find a dust seal and spring beneath.
Image01329.jpg
try not to lose anything...

The spring supplies about half the return force required for the main (downshift) lever. At this stage the front pivot bushings (#9 etc) may or may not come out of the front of the lever too.

Step 2 is to remove the lever assy from the bracket. You need to use a 2mm allen key to unscrew an M4 grub screw that locks the lever pivot shaft in position. The screw doesn't have to come out, if you back it out two or three turns that is plenty.
Image01330.jpg
this screw may be very tight; use a really good quality allen key

Then drive the pivot shaft out of the lever body; Sometime this is tight, other times it practically fall out
Image01331.jpg
make a note of where the long end of the spring is anchored

It is probably best to remove the brake cabe anchor and the spring and bushes that are associated with the main pivot shaft; they can easily become lost later on otherwise.

Step 3 is to separate the main (downshift) lever (#10) itself from the shifter internals. There is a small screw (#4) at the back of the shifter internals. In most cases this screw is hidden by the upshift lever. Moving the upshift lever to one side (and holding it apart from the downshift lever using your thumb) allows access to this screw.
Image01332.jpg
I think it is a JIS type Phillips #2 point

once this screw is removed the lever (#10) will slide off the main shaft, allowing excellent access to the shifter workings.

-----continued in post below-------
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Brucey
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby Brucey » 27 Aug 2018, 12:01am

--- continued from post above-----

Image01333.jpg
a right mess of pawls and so forth


The following photos show different views of the (RH shifter) mechanism: parts are located as per a clockface view from the front, i.e. with the upshift lever normally at 6 o'clock, and the spool rotating ACW on downshifts.

Image01334.jpg

Downshift drive pawl (6-o'clock position) to left of centre shaft

Image01335.jpg

downshift drive pawl uppermost

Image01336.jpg

side shaft (2-o'clock position) uppermost. Both holding pawl and index pawl are mounted on this shaft.

Image01337.jpg

upshift drive pawl (small, 12-30' position) is almost in line with my thumb. Nearer the top of the photo you can see the side shaft, side on, with holding and index pawls in position.

You can exercise the mechanism by holding the rear bracket (gently) in a bench vice, and working the downshift mechanism by using a small adjustable spanner that is snugged over the bracket that the small screw (#4) sat in. The upshift lever can be used in the normal way.

You will see that each lever drives the mechanism via its own driving pawl that is not engaged with any corresponding ratchet wheel except when it needs to be. Near the centre of the mechanism there are two pawls sat side by side; the rearmost of these is the index pawl (that defines the position of the spool when the shifter is not being used, i.e. when set in any given gear) and the frontmost one is a 'holding pawl' that engages with a separate wheel, and makes sure that the index wheel cannot rotate in an uncontrolled fashion, mid-shift. The latter two pawls work a bit like a conventional escapement mechanism in a clock, but because they are operated almost independently, the mechanism is more secure and tolerates wear rather better. There are also parts that securely block the holding pawl, so that it cannot disengage mid-shift.

The pawls mostly have their own springs and the springs should be intact and the pawls should be free-moving too.

Common faults are that;

-The upshift or downshift lever moves freely and does not drive the mechanism; this is commonly caused by a sticky driving pawl, occasionally by a failed pawl spring. If you have this fault try method a) first. You can see in the photos roughly where the pawls sit in the mechanism, and this may help your aim.

-The mechanism is always stiff to move; the main pivot shaft may need lube, or the front spring may be disturbed, or there may be foreign matter in the mechanism.

- The mechanism is initially stiff to move during a downshift (esp starting in the top gear position) ; this is most often caused by the index pawl being stiff to move on its shaft, or there being no grease where the index pawl bears against the index wheel.

- When the upshift lever encounters signficant resistance (just before the shift goes) the action is heavier than normal; this is usually caused by the holding pawl blocking action being stiff; more lube on these parts normally fixes it.

Obviously if there are broken parts then the third option [ option c), a complete stripdown] is required. However my duff bike-jumble shifter turned out not to need that; when I removed the downshift lever, a tiny part that I barely glimpsed, fell onto the floor. Cursing, I retrieved it only to find that I had recovered the nipple from an old gear cable; this had been rattling around in the workings (it wasn't lodged in the spool like you might expect) and it was a miracle that the shifter had appeared to shift correctly even once....

Reassembly (once you have cleaned/lubed the workings to your satisfaction) is 'the reverse of the disassembly procedure' as a haynes manual might say. Really there are only two tricky bits; first, the front cover should be attached to the lever mechanism (pref held in a bench vice) before the latter is remounted to the main bracket. The front cover spring is not identical at each end (and I think that the end with the short straight section should face the lever not the cover) and the spring needs about 1/4 turn preload which is a little bit tricky to achieve (it took me a couple of goes, holding the cover at an angle so the spring ends didn't pop out). Second, there is a spring in the brake lever main pivot; this should be hooked into the steel lever bracket, and the short end can bear against the main bracket if the lever assy is raised into position in a certain way; again it can take a couple of goes to get this right.

It takes a lot longer to read about option b) than it does to actually do it, especially second time around. I reckon I could get to where all the pieces are as apart as they need to be in less than ten minutes. Reassembly takes a bit longer.

Obviously if option b) didn't work for you, it is on to option c)....

c) A complete stripdown. I found this online guide (to ST-7400) with pictures:

https://imgur.com/a/4IT1J

I have not had to do this yet, but I believe it is just as awkward to do as it looks. You need a special tool (which can be made from a 1/4 drive socket with a carefully ground end) to undo the nut that holds the rear of the mechanism onto the steel lever bracket. Lots of parts come free as soon as you remove this....

Well I hope this helps folk out some; IMHO option b) is not very difficult and it allows you to clean and lubricate the mechanism far better than option a) ever could.

cheers
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geomannie
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby geomannie » 27 Aug 2018, 1:05pm

"they narrow your choices of derailleurs, sprockets etc and brakes to a small fraction of all those available; a kind of self-imposed tyranny if you like, since very many riders wouldn't consider buying a dropped handlebar bike without them, even though I'd describe them as contributing to a 'marginal gain' rather than transforming the way you ride."

I am intrigued to see you write this. I ride with a group of older, non-competitive riders and while on our annual 100 miler last Saturday, I was trying to explain to a group member, all kitted out with Di2, why I had replaced my STI's with bar-end shifters (friction mode) running 9 speed. I punted the ideas of robustness, simply, flexibility (can run 8/9/10 speed cassettes), riding style (we are certainly not racers), cost and so on, to be met by a blank stare. I suppose its horses for courses but in 5 years’ time I know which setup has the greater chance to still be working.

Also, I prefer riding bar-ends in friction mode. There is none of the frantic clicking when you want down-shift in a hurry.
geomannie

Brucey
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby Brucey » 27 Aug 2018, 1:25pm

the fact is that most riders see STIs as being 'the norm' and moving to Di2 just offers another 'marginal performance gain' in return for yet further narrowed choices.

If all you do is pootle about on a sunday then (regardless of the equipment used) worst case is that you have a day's ride spoiled and it costs you some money to have repairs carried out. If you are not mechanically minded the idea of being able to discriminate between one system and another (beyond the 'headline attributes') leave alone fix anything in the event of problems is somewhat alien. Often the thought processes involved don't extend much further than newer, more expensive, pros use it etc therefore must be 'better'.

BTW if you want to use friction mode all the time then simplex retrofriction or suntour/dia compe 'powershift' levers (although these click too.... :wink: ) give the easiest shifting; better than a set of indexed levers with the indexing turned off.

cheers
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Brucey
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby Brucey » 27 Aug 2018, 3:52pm

further to the above here is a picture of a LH RX-100 STI internal:

Image01338.jpg
RX-100 LH shifter


Construction is similar but not identical to the RH shifter. Access to the pawls etc isn't as good as with a RH shifter, because there is a large plastic cowl that remains attached to the mechanism. However you can see the main drive pawl (for upshifts, this being for an FD not an RD) at the 6 o'clock position (left side in that view). The downshift drive pawl is lurking out of sight near the back at the ~4 o'clock position, and the other pawls are beneath the cowling at the 12 o'clock position; readily accessible for lubing.

This shifter would respond to spray lube and work for a few months, then gum up again. It is now lubed with a (synthetic oil based) SFG, works more smoothly than it ever has done before, and should go for several years without further attention.

BTW the most common fault previously was that the shifter wouldn't downshift onto the small chainring, which is (as previously described) usually a fault with the drive pawl connected to that lever. With this model of LH shifter, holding the main lever to one side (as if shifting onto the big ring) and using an angled 'straw' on the aerosol should allow you good aim at the downshift drive pawl (at the 4 o'clock position). But if you didn't know where it was you could spray away randomly and not get very much lube in the places where it is really needed.

cheers
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tim-b
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby tim-b » 28 Aug 2018, 6:26am

Hi Brucey
I admire your love of things technical and mechanical and I don't want to detract from a clear, well-illustrated article, however, an ST1055 from 1996 finally needing a service doesn't point to an unreliable concept
I'd agree that some models have been better than others, but there are very few moving bicycle components that can survive 20+ years in the field with minimal/no attention
I have L&R ST5600 shifters in a box that saw faultless all-season action for five years on my commuter/winter bike until the bike was retired due to fork damage
EDIT: I should add that having had experience with down tube and bar end levers over decades, and about 15 years experience of ST levers then I would go for STs every time. I spend most of my time on the hoods and the ability to change gear efficiently with very little movement is a delight
Regards
tim-b
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Brucey
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby Brucey » 28 Aug 2018, 10:46am

Not really the point of this thread to get into a debate about the virtues of STIs or not, (and maybe you didn't read and inwardly digest what I wrote above) but

a) I have specifically identified these models of STI as being rather better made than many others (*)
b) such STIs commonly fail (e.g. become gummed up) whether they are used or not. Often a 'failed set' won't have even had the moulding marks worn off the original hoods.
c) one thing you definitely shouldn't do is leave a bike with STIs on out in the weather; the water gets into them too easily when it rains and this wrecks them; unless the workings are properly corrosion proofed, they are for various flavours of 'toy bike' not true utility machines. [BTW flat bar pods are better in this respect but are still vulnerable to the weather.] If you ride in all weathers and don't lubricate your STIs regularly they are very likely to fail.
d) They are (in most cases) nowhere near reliable enough or resistant to crash damage; go into any LBS and they will have a box of STIs (that they are keeping for external spare parts, or for odd ones that are still serviceable from a broken pair, they can't fix them per se). They fail often, and some models are just very much weaker than others.

So I will stick with my original view of 'expensive, cumbersome, choice-limiting, easily damaged and not (outside of actual racing) even much of a real benefit anyway' . My point in this thread is that

a) they are not all built the same by any means and
b) contrary to popular opinion, it is not that difficult to do something other than lube them from outside or throw them away.

(*) For some years there have been a few folks who offered a repair service for STIs (I think the 7400 stripdown I have linked to has been posted by one such). It wasn't uncommon for such folk to refuse to repair sora STIs (not worth it and they would only break again anyway) and also 9s and 10s STIs ('not designed to be properly reliable in the first place').

cheers
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hamster
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby hamster » 28 Aug 2018, 4:56pm

Brucey wrote:In my mind I have a special place in hades reserved for the person that thought that indexed front shifting was a good idea; the amount of time wasted on this particular item is almost unbelieveable...


I absolutely agree.
It also amazes me that Shimano manage to make shifters with about 2x the number of parts as Campagnolo. It's a pity that Campag shifters also aren't as flexible and serviceable as the older ones around 2000.

De Sisti
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby De Sisti » 28 Aug 2018, 5:05pm

Makes me think more and more about selling my Campag Ergo levers and buy downtube shifters.

Brucey
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby Brucey » 28 Aug 2018, 6:34pm

campag ergos are rather simpler inside than shimano STIs. However, even good ergo designs also wear out at regular intervals and campag have basically stopped selling individual spare parts for many ergo models so those shifters which used to be fairly sustainable (about £20 worth of spare parts ought to rebuild a typical ergo) are now repairable only by replacing a whole assembly that is almost the same cost as a whole shifter......

For alternatives one only needs to look at what has been used in the past and what is used on other types of bike to get an idea of what ought to work well enough on a touring bike. Remember these?

Image

They were shimano's attempt to prove that wabbling the brake lever around to change gear was a truly ergonomic solution to shifting and braking, even on flat bars. Even the thumbs buttons were optional, and could be unbolted... Needless to say no-one considers this sort of shifter 'essential' on a bike with flat bars, even though the rate of shifting is often a lot higher on well-ridden MTBs. Most folk use separate shifters that are merely fairly close to the normal hand position and/or close to the brake levers.

I think the same rationale applies to bikes with dropped handlebars; shifters near the stem, under the tops, near the brake hoods etc I think are a good compromise for touring bikes.

I also find it slightly baffling that in the face of a massive proliferation of shifter types, and brake lever pull ratios, no-one has come up with a brake lever for dropped handlebars that has an adjustable pull ratio, and similarly why no one has come up with a shifter that can easily be reconfigured to work with almost any system. it ought not be rocket science to do this....

cheers
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tatanab
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby tatanab » 28 Aug 2018, 6:47pm

Brucey wrote:similarly why no one has come up with a shifter that can easily be reconfigured to work with almost any system.
There's Modolo Morphos https://www.modolo.it/products/componen ... hos-lever/ I tried an early type in 1999, 7 speed I think. The problem I found was that braking was very spongy due I think to the shape of the lever and the way the brake cable wraps over a pulley in the lever.

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Graham
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby Graham » 28 Aug 2018, 7:43pm

Thanks to Brucey for another masterful exposition.

Back in 2013 I managed to get a pair of RSX 2*7 STIs working again by following some internet instructions & pictures.
I have just checked and they are still live.
viewtopic.php?f=5&t=82413

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NATURAL ANKLING
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby NATURAL ANKLING » 30 Aug 2018, 1:29am

Hi,
I have yet to move into the twenty-first century, I have never tried sti's. :?
Can you brake and change gear at the same time?
You can with standard flat bar shifters integral with brake levers, got to be the most ergonomic set up.
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby tim-b » 30 Aug 2018, 7:30am

Hi
On the same lever (i.e. F brake R mech)? You certainly can with Shimano, although some makes/gear changes will need more concentration than others
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tim-b
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Brucey
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Re: 7/8s Shimano STIs; not quite so horrifying inside after all

Postby Brucey » 30 Aug 2018, 8:12am

I'd say that during actual braking some shifts are impossible and others are only possible as long as you are not actually braking very hard. If you are hard on the front brake, actually getting an STI downshift lever swung far enough to initiate a shift is very difficult. On RH shifters where there is a separate paddle for downshifts it is almost impossible when the brakes are being applied. If you are only shifting when the brakes are not being applied hard, you can achieve a very similar result by using entirely separate braking and shifting manoeuvres instead. I note that here, right front brakers have different possibilities to left front brakers.

Obviously wanting to upshift whilst braking isn't something that is terribly useful, except as part of a double shift. Here I think that Campag ergos have it over STIs; you can doubleshift (using your thumbs only) and this isn't that difficult to do whilst braking. However I still don't think that you could brake at full power and work the thumb buttons though.

The main benefit seems to me to be that (as with flat bar controls) you don't have to move your hands far so you can be faster to transition from braking to gear changing, or can brake with one hand and shift with the other. Even when riding a whole load of nadgery stuff on an MTB it isn't that common that you would want to do this, (but it happens enough that I actively prefer an MTB triple over a double setup, simply because you can brake hard with the front brake and can downshift with the left shifter onto a smaller chainring, such that you have a choice of two (from the big ring) according to how steep the next bit is).
When riding a derailleur geared road bike this is hardly ever required. I guess the most common occasion is when pulling up to traffic lights; with many setups dropping onto the small chainring gives you a gear that is OK for starting on, and only deprives you of the rear brake for a second or so even if you cannot shift and brake hard at the same time. Arguably (since it is a planned braking manoeuvre) you would tend to ride more safely (i.e. with a bigger margin for error) if you cannot shift and brake at the same time; eg when using DT levers one tends to get the braking mostly done, then shift whilst travelling at very low speed, and then finally halt. Thus braking is naturally both prioritised over shifting and is carried out earlier than it would be otherwise.

For urban riding on dropped handlebars, there is much to be said for having interrupter brake levers and to have the shifters within easy reach of those; this gives you a 'head up' riding position, not unlike that on flat bars.

cheers
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