Towards Blissful shifting; what about older mechs?

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Brucey
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Towards Blissful shifting; what about older mechs?

Postby Brucey » 12 Sep 2019, 10:14pm

I remember (just) a long time ago (in about 1984), viewing the most recent derailleur developments with a mixture of genuine interest and suspicion. Interest because the new thing was shimano's SIS 'indexing' with promise of accurate and rapid shifting, and suspicion because most of the derailleur setups I'd used to date (including some which were meant to 'index') had zero chance of operating reliably as an indexed system, and besides which wouldn't all those clicky bits go wrong, or out of adjustment, so that the indexing would be worse than useless? Wouldn't this whole scheme suit unskilled/novice riders, who might struggle with the gears otherwise? Would it be a mark of shame for a more experienced rider to use it, or would it offer a genuine competitive advantage?

I was slightly mollified by the presence of a little switch on the gear levers that meant that if the indexing stopped working, you could revert back to friction mode. I may have (slightly grumpily) pointed out that the resulting friction shift "wasn't that good", and the friction value couldn't be adjusted, but really I was nitpicking. However to get indexing to work there were a whole bunch of detailed changes which might today be taken for granted, if they are not missed altogether. Amongst these were;

- Better rear mech geometry; Sun Tour's slant parallelogram patents had just expired and when combined with twin-sprung 'servo-panta' springs (which in fact simplex had been doing for decades) shimano's rear mechs were suddenly far better than they had been previously.
-indexed levers of course. These had to be bullet-proof more or less.
- uniformly spaced sprockets.
- A slightly floating 'centreon' top (guide) pulley gave the whole system a little tolerance for bad adjustment
- carefully shaped teeth on the guide pulley gave the pulley good lateral traction even on modern bushingless chains
- new, tighter tolerances for the gear hanger alignment ensured that the shift would be crisp unless the mech itself was bent
- new more demanding requirements for cable guides and cable ferrules meant that standard friction shifting was improved and SIS was reliable.
- 'Uniglide' shaped sprocket teeth allowed a better shift with the 6s (and later 7s, 8s ) systems
- specific chains were approved for use with shimano's uniglide sprockets. Shimano UG chains of course but they also specifically allowed Sedisport chains, which were then near-ubiquitous in professional racing.
-compressionless 'SIS' cable housing, with a low friction liner, meant that cables moved easily and indexing stayed in adjustment. [The housing was derived from that deemed necessary for shimano's 'positron' system to work. In case you are wondering 'what did positron ever do for me?' , that would be it.]
- pre-stretched inner cables
- polished stainless steel inner cables

Further evolution gave us

- even slicker shifting HG sprockets and chains
- STis (with no friction mode, horror!)
- 'sealed' cables
-MTB indexed systems, which in some cases used different shift ratios slightly different cable pulls and/or chain/sprocket clearances, but by and large retained a lot of compatibility with road systems too.
- ever more sprockets at the back
- ever cleverer variations in the HG-esque design features that make n+1 shifting viable.

On the plus side these days you can buy an OTP bike with a bazillion gears and have a reasonable expectation that shifting will be pretty slick, easy and reliable. On the minus side, these systems that work so well have ever more expensive parts to them, which are all easily damaged in the event of a prang. Also these systems normally only work perfectly as systems, which means that if you want a number/type of shifter/range of gears that the manufacturer hasn't anticipated, you can be pretty stuffed. At best you are usually left with a mishmash of bits and at worst you are left struggling to get anything that works at all well.

This much we know; welcome to the modern world. But are there other implications for modern shifting technology? Well, yes, I should say there are; the technology has quietly trickled down into the lower echelons which means that you can enjoy shifting quality and reliability that was bascially undreamt of, years ago. For example BITD a 6s uniglide setup (e.g. an 'A' series mech from the midrange echelons, when 7s was current) might have been a bit finicky and more than a little clunky. But today even a cheap freewheel (like a Sun Race one, with its faux-HG tooth shapes) and a cheap chain (eg a KMC one) when paired with this shifting setup offers really reliable/slick shifting. One of my chums has exactly this setup on his commuting bike and (having been set up properly) I don't think the derailleur/cable has been adjusted in over 15000 miles, during which time it has quietly (and inevitably) consumed several chains and freewheels.

Similarly if you pair even much older RDs -which were not always stellar performers BITD- with modern chains and sprockets the shifting can be almost unrecognisable when compared with that achieved with old style chains and sprockets.

So I for one am grateful for advances in shifting technology, even if I'm taking advantage of them in ways which the manufacturer's didn't necessarily expect.

if you have not tried it recently, very many flavours of friction shifting, even with older RD designs, work surprisingly well provided you use 6/7/8s HG-style sprockets and chain.

I plan another post with 'wrinkles' and workarounds in it; watch this space....

cheers
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Brucey
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Re: Towards Blissful shifting; what about older mechs?

Postby Brucey » 12 Sep 2019, 10:14pm

'Mind The Gap"; the importance of the guide pulley gap.

BITD one of the things that had a major influence on the shifting performance of any given system was the size of the gap between the guide pulley and the sprockets. Make this 'guide pulley gap' (GPG) small enough, and better -or at least more reliable- shifts were assured. If you got it small enough you might expose other sources of baulky shifting, such as worn, or flexible RDs. You would certainly notice if you didn't position the RD correctly; much chattering was possible if the alignment wasn't quite right. I expected further improvements in shifting to come from better controlled GPGs, and better RDs that were stiffer and wore more slowly. For racing, you can't really ever have shifts that are accurate or fast enough; BITD I spent some time making sure that the shifting was as good as possible, given the bits I was using.

Amongst other things I

- experimented with different combinations of chain and sprocket
- experimented with different guide pulleys (shape, bearing type) and material
-experimented with different gear levers, eg with different amounts of built-in overshift
- experimented (endlessly, inevitably) with different RDs and RD setups.

For example at one stage I used a 600EX RD, (the last one with a non-slanted parallelogram) and for racing I revised the spring in the upper knuckle, as well as fitted different jockey pulleys which gave me better shifting. I also experimented with my own modified UG-esque sprockets, which meant that I had much improved shifting even when using non-index type Sun Tour sprockets.

Back then the GPG was crucial. It remained crucial with the advent of indexed systems, too. in those days if you had suggested to me that gear hanger extenders might ever be 'a thing', I'd have gone "pwfft, yeah, and monkeys might fly out of my butt" or something. Yet here we are, they are a thing and folk ride around quite happily with them fitted to many systems.

So what is different? The answer is that the designs of chains and sprockets have, quietly, been getting even better. The ramps and truncated/asymmetric teeth of early HG designs are still with us, but now they are combined with heavily chamfered tooth tops, occasional extended 'pickup' teeth, chains with better shaped side plates, and tighter tolerances for the fit of the chain vs the sprocket than ever.

All this means that a new 11s setup can have a large GPG and it will still shift uncannily well. In tests I have done, the GPG can be about 50mm before the shift quality is noticeably affected. In the simplest terms a major difference is that with flush "bullseye" riveting in the chain, and a defined clearance to the sprockets, when you start to move the chain, the chain side plates can hook up on the sprockets quite easily and this quickly/easily initiates the shift.

By contrast with any chain (which includes all chains up to 8s and most 9s chains too) where the rivet heads protrude slightly, these are of course the first things to clatter against the adjacent sprocket. Unfortunately they are never going to hook up on the adjacent sprocket all that well, so shifting -whilst greatly improved vs old pre HG tech- isn't quite as slick with these chains. In the simplest terms you might expect to get the best shifting with chains that have the flushest rivets, the most cleverly shaped side plates, have controlled degree of flexibility and that have a particular fit vs the sprocket spacing.

I don't expect an 11s system with a large GPG to carry on shifting perfectly; I expect the lateral 'stiffness' of the chain to change with wear, the crisp edges on the chain and sprockets to be lost and for the shifting performance to deteriorate accordingly. But basic 11s chains are fairly cheap now, and if you change them soon enough the sprockets can be made to last longer than you might expect. Shift ratios in RDs have changed too.

All this means that you can do all kinds of interesting things, for example run a reduced cluster (eg 7 or 8-from-11) on a 7s (or narrower) freehub, giving a virtually dishless wheel. If you choose your RD shift ratio carefully, you can expect it all to work with 7s or 8s indexed levers, too.

It also means that older-style RDs may have a use again; vintage bikes can be made to have shifting that is far better than it was years ago; there are (as ever) substantial differences in shift quality with different combinations of sprocket, chain and RD.

I'm hoping that we get 6s/7s/8s chains with 'bullseye' riveting, in fact. I think these will give even better shifting on 6/7/8s systems, even with vintage RDs.

cheers
Last edited by Brucey on 12 Sep 2019, 11:52pm, edited 1 time in total.
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Brucey
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Re: Towards Blissful shifting; what about older mechs?

Postby Brucey » 12 Sep 2019, 10:15pm

Part Three; Lateral traction of the Guide pulley.

It may be blindingly obvious to say this but no derailleur is going to be able to push the chain sideways if it has no lateral traction on it. This traction is reliant on the nature and quality of the fit between the guide pulley and the chain. It is one aspect of derailleur design that has changed significantly over the years.

It is also something that needs to be borne in mind, especially when contemplating the use of an older derailleur with more modern chain and sprockets.

When derailleurs were still a fairly new idea, it was quite normal for guide pulleys to have full-height teeth, just like any other sprocket; this always gave good lateral traction on the chain, and shifting performance was unlikely to be limited by the amount of lateral traction available. Indeed it could be argued that it was easy to end up with too much traction, and this may allow frenzied tugs at the gear lever to apply excessive load to the rear mech.

in terms of torque transmission, practically no tooth height at all is required on either pulley; the torque needs to be sufficient to turn the pulley bearing, and no more than that. It could be argued that -provided there was still enough lateral traction- there is no need to have any teeth at all on the pulleys; a free-running pulley bearing would be happily turned by mere friction alone. Thus BITD some pulleys were indeed made perfectly circular (eg Huret) and some were made circular but with tiny dimples (eg Campag Gran Sport steel pulleys). If the pulleys didn't turn, this was usually the pulley bearings issuing a plea for help. Note that when campag quietly abandoned ball-bearing pulleys (which may have roughly coincided with the introduction of the Nuovo Record RD) the pulleys grew small teeth again, presumably to make sure that a slightly draggy pulley bushing didn't cause the chain to slide over the pulley rather than turn it.

In those days freewheel sprockets had full height teeth and the most common thing was that the chain and the sprocket were run as a set until 'something bad happened'; for example the transmission started running rough, slipping, or the teeth started breaking off the most used sprockets or perhaps it became obvious that the chainrings were taking a pasting. Anyway sprockets with full-height teeth soon became too hooked to accept a new chain without complaint, and it wasn't at all unusual for a chain to elongate by 1-2% before time was called on it.

Between chain pitch variations and slightly draggy bushings, it is not at all unusual for derailleur pulleys to wear badly; in essence the pitch of the chain is increasing as it wears, but again because of wear the diameter (and thus the tooth pitch) on the pulleys is at the same time reducing. This leads to the chain rollers moving around on the face of every pulley tooth, and wear rates are liable to increase rapidly. Maybe this was another motivation towards round pulleys? I have many times seen pulleys on neglected bikes worn to tiny, vestigial remnants....

Furthermore folk have always pushed their luck with derailleur capacity; one of the consequences of this is that the guide pulley can get too close to the sprocket teeth; if they should contact one another there is a distinctive 'grrr' sound. Often a marginal setup with a sprung upper knuckle would run OK forwards, but backpedalling would be accompanied by the 'grrr' noise. Needless to say if the guide pulley has no teeth on it, even full height sprocket teeth can't contact it so easily.

Anyway, if the guide pulley has no teeth or very small teeth, it won't have good lateral traction with every chain. More than one cycling enthusiast has commented to me that the shifting with an old mech (eg an old campag gran sport with steel pulleys) is 'complete rubbish'. Of course the mech could be bent or worn out, but IME if this is not the case, they are Invariably using a modern bushingless chain, often in combination with an older freewheel design, with full height sprocket teeth. Obviously the sprockets don't help slick shifting at all, but the major problem is usually a complete lack of lateral traction between the guide pulley and the chain. BITD most fully-bushed 3/32" chains had deeper inner side plates and these afforded some lateral traction even with a toothless guide pulley. There is no such traction with a modern bushingless chain; often the inner side plates are barely more than flush with the tops of the rollers. Thus you can usually see the chain able to leave the guide pulley at a jaunty angle, making that familiar 'not gonna shift anytime soon' kind of sound.

There are two options here;

a) use a fully-bushed 3/32" chain, with deeper inner side plates. These are not easily found, (and nor are they particularly good perhaps) but both KMC and Wipperman do make such chains. This restores the shifting (with old-style/vintage sprockets) to all its clunky period-correct glory. Shifting is improved (even with that chain) if you use a 5s/6s freewheel with more HG-esque tooth shapes.

b) fit a guide pulley with more pronounced teeth on it. This will allow better lateral traction even with modern bushingless chains.

Many recent derailleurs from the leading manufacturers have been going down the b) route recently. With modern chains and sprockets the guide pulley gap (GPG) is no longer so critical for good shifting, so average GPGs can be increased. There is therefore less danger of there being contact between the guide pulley and the sprockets, and more pronounced guide pulley teeth are better tolerated. For a while some shimano 11s mechs came with a different guide pulley depending on the length of the cage; short teeth with an SS mech, longer teeth with a GS mech. Now almost every 11s shimano mech comes with a very toothy guide pulley, and is probably all the better for it, too.

If you can find a (modern) toothy guide pulley that fits an older rear mech, you can enjoy improved shifting, even with bushingless chains. Obviously HG-esque sprocket teeth on the freewheel help; not 'period correct' of course but I'd sooner have improved shifting (not to mention more easily replaced consumables) if I'm riding the bike far.

Unfortunately modern guide pulleys are different; they are not only a bit narrower (which is easily overcome by adding spacer washers) but they are also often larger, e.g. 11T (or more ) instead of 10T. A 1T increase in size is usually tolerated OK, but not always. Obviously taller guide pulley teeth can clash more easily with larger freewheel sprockets... Anyway if you can fit a properly toothy guide pulley to an older mech, you can enjoy much improved shifting, even with bushingless chains which were never designed to work with those mechs originally.

cheers
Last edited by Brucey on 13 Sep 2019, 10:14am, edited 1 time in total.
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Spinners
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Re: Towards Blissful shifting; what about older mechs?

Postby Spinners » 12 Sep 2019, 10:46pm

Both my hybrids are running on 7-speed (one is 3x7 the other is 1x7) but these use modern Tourney RD's. What I really want are nice 7-speed cassette road hubs (130mm spacing) but that's for the future.

The only time I used 7-speed DT levers was on my 531ST winter bike in the mid-90's and the frame was springy enough to take an LX rear hub and I used 52/42 up front and 13-21 at the back despite our club runs roaming all over South Wales! I just can't remember what RD it used though (probably RX100) but it all worked flawlessly.

looking forward to the next installments!
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peetee
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Re: Towards Blissful shifting; what about older mechs?

Postby peetee » 13 Sep 2019, 5:56am

My 1990 MTB still runs XT 3x7 hyperglide. When I ressurected it a few weeks ago I thought, given that my other bikes are running more cogs, that I would find the 7 cogs inadequate. Quite the contrary. The shift is so foolproof and slick front and back I absolutely love it.
Current status report:
Latter side of fifty and feeling less than nifty.
Too many bikes on pegs and too few miles in the legs.

Greystoke
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Re: Towards Blissful shifting; what about older mechs?

Postby Greystoke » 13 Sep 2019, 6:28am

My commuter bike which i cycled to work on again today has worked flawlessly for years with the 5 speed SIS system :D

ElCani
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Re: Towards Blissful shifting; what about older mechs?

Postby ElCani » 13 Sep 2019, 7:11am

Interesting posts, thanks. On the subject of GPG, I’ve noticed this is extremely important with the new 12 speed SRAM MTB systems. I work with these a lot and they simply don’t function properly unless the B-screw is very carefully adjusted. Usually they won’t shift from the largest to second largest sprocket (when the indexing is correctly set), but other glitches are not uncommon. I’d got used to precise b-screw adjustment being fairly non-critical with 7-8-9-10-11 speed, but that’s not the case with these systems. Hanger alignment is also very important.

It’s notable to me that the lower-end NX groupset is the most finicky to set up and I’m doubtful about the long term reliability of these set-ups.

Brucey
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Re: Towards Blissful shifting; what about older mechs?

Postby Brucey » 13 Sep 2019, 8:20am

that is an interesting comment about 12s. It occurs to me that

a) maybe there is a limit to how far you can push a chain sideways...? and/or
b) maybe the first sprocket on 12s cassettes deliberately has less in the way of shifting aids, perhaps with a view to reducing the chances of shifting 'through' that sprocket and into the spokes?
c) to maintain a roughly constant %-age interval in the cassette, the jumps (in teeth) get bigger and bigger as you change onto larger sprockets. At some point it won't matter how cleverly designed the teeth are, the shift will be more baulky.

With these things in mind maybe I shall take a closer look at the next 12s cassette I come across.

I'd also note that in many modern derailleurs, the parallelogram geometry is no longer 'perfect', i.e. the 'toe' angle of the guide pulley varies through the derailleur stroke, presumably because this allows the chain to enter the tension pulley at a slightly more favourable angle when running cross-chained. This benefit must be balanced against variations in shift quality at the extremes of the cassette.

cheers
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NetworkMan
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Re: Towards Blissful shifting; what about older mechs?

Postby NetworkMan » 13 Sep 2019, 9:43am

Brucey wrote:I'd also note that in many modern derailleurs, the parallelogram geometry is no longer 'perfect', i.e. the 'toe' angle of the guide pulley varies through the derailleur stroke, presumably because this allows the chain to enter the tension pulley at a slightly more favourable angle when running cross-chained. This benefit must be balanced against variations in shift quality at the extremes of the cassette.

cheers

A slight diversion here. I've always wondered if there is or was a variation in slant angle between road and mountain bike RDs or perhaps between long and short cage ones. Since mine are all mountain bike types I've not been able to look closely but don't recall seeing this discussed. I'd imagine that a cassette with sprockets similar in size might be best served by an RD with small slant.

Brucey
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Re: Towards Blissful shifting; what about older mechs?

Postby Brucey » 13 Sep 2019, 10:21am

yes the slant angle is varied with the envisaged use of the RD. In combination with a sprung upper knuckle, there is some tolerance, but with the change to fixed upper pivots (again; older sun tour mechs were always like this) the slant angle has to match the cassette size reasonably well if a consistent GPG is to be maintained.

One approach to making a more versatile RD was tried by campag; the first 'Chorus' RD design allowed the slant angle to be adjusted between two positions; nearly flat for a racing cluster, or angled for a touring setup. IIRC in the latter configuration, a 32T sprocket was possible...? Anyway this design didn't catch on; shame really, I thought it was quite good.

BTW even 7s indexing is better now than it ever has been; some cassettes come with even better versions of HG tooth shapes, and chains are better-shaped too. A basic KMC chain seems (to me) to shift far better than (say) sedisport (and by extension some current SRAM) chains ever would.

cheers
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NetworkMan
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Re: Towards Blissful shifting; what about older mechs?

Postby NetworkMan » 13 Sep 2019, 11:19am

In combination with a sprung upper knuckle, there is some tolerance ......

Yes there sure is. My sweetest changing bike has, at the moment, an 8 speed 13-26 cassette and a cheap Acera 8 speed mountain bike RD intended for min. 28T large sprockets!
Probably the reason for that is that the other two bikes are running with wide range cassettes (13-30 7 speed and 11-32 9 speed) which just don't change so smoothly.

Brucey
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Re: Towards Blissful shifting; what about older mechs?

Postby Brucey » 13 Sep 2019, 11:26am

what language is that? I wondered....

Image

'tis the language of marketing, that. In the 1950s the bike company 'Hercules' saw fit to invent a new word to use on their derailleurs. No idea if such a device could/would shift well with modern chains and sprockets.... anyone tried it?

cheers
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Re: Towards Blissful shifting; what about older mechs?

Postby amediasatex » 13 Sep 2019, 11:53am

I've got (too) many bikes and setups ranging from one speed, through 5,7,8,9,10 and 11 speed derailleur, and 3,8,11 speed IGH from various manufacturers and everything from complete matched groups to complete hodge-podges and one of my favourite and most used setups is a complete multi-decade mish-mash that runs perfectly, and in some ways superior to my more modern 10 and 11 speed setups.

2004 Campagnolo 10 speed Ergos
1978 Suntour VX Rear derailleur, short cage
1996 Shimano RSX 'hybrid' front mech for 28/38/48 so different cage angle and pull ratio to the road mech
SRAM 8 speed 12-28 Cassette with the top 4 sprockets custom spaced
Stronglight/Spa triple cranks with 26/36/48 TA Rings

Samuel D
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Re: Towards Blissful shifting; what about older mechs?

Postby Samuel D » 13 Sep 2019, 12:47pm

Brucey wrote:I'm hoping that we get 6s/7s/8s chains with 'bullseye' riveting, in fact. I think these will give even better shifting on 6/7/8s systems, even with vintage RDs.

Aren’t Wippermann Connex 800-series chains (at least some of them) already like that? The pins still slightly overhang the plate though.

ElCani wrote:On the subject of GPG, I’ve noticed this is extremely important with the new 12 speed SRAM MTB systems. I work with these a lot and they simply don’t function properly unless the B-screw is very carefully adjusted.

And yet careful adjustment doesn’t mean minimal gap, right? I read of a specific gap distance in some SRAM documentation (before 12 speed). I have wondered why that might be. Why wouldn’t the smallest gap always be best?

Brucey wrote:A basic KMC chain seems (to me) to shift far better than (say) sedisport (and by extension some current SRAM) chains ever would.

Never noticed with my 8-speed 13–26T system that just goes BAM, BAM, BAM through the gears in any direction, any weather, practically instantly, with a SRAM PC-850. I don’t believe further improvement would make any difference to me, even for racing.

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Re: Towards Blissful shifting; what about older mechs?

Postby francovendee » 13 Sep 2019, 1:01pm

Very interesting and wonder what comes next. Today we've got 12(?)speed and electronic shifting. Are we coming to the end of possibilities?
I've noticed that jockey/pulley wheels have become larger. Does this change make shifting better?