onre

So,

I've got a Golden Arrow rear derailleur and Altus-LT friction levers on my bike. Altus-LT levers have the free play needed for the Centeron system to work, but Golden Arrow doesn't seem to have the floating pulley. This setup kind of worked with the old 6-speed freewheel, but with the current 7-speed one it's not very accurate on middle sprockets, leading to autoshifting. I've thought of replacing the levers with ones without the free play and see how that changes the situation.

Any thoughts?

blamester

I removed the floating pulley wheel with no problems in a friction system. Actually worked better. Hg chain and cassette. Friction levers shouldn't have play at the lever.
There can be a little slop in index mode.
So perhaps this is not the problem.
As an aside 11 speed seems a step to far so I may go back to the floating pulley to see if it helps, if not back to 9 or 10 speed.

onre

The Altus-LT levers are actually designed to have a little play on the right-side lever, as explained here:

Shimano Bicycle System Components (1982) page 15

However, I suspect this not to work so well if there's no floating pulley in the RD.

The Golden Boy 

I agree- there should be no slop in the shifters.

The Centeron pulley is there because there NEEDS to be slop in the index system so that the cog teeth and chain can meet up when they’re in the neighborhood of each other. With friction, it’s not that important- you can always trim- indexing doesn’t have a trimming option.

onre

I'm pretty certain there shouldn't be any slop in the shifters either, but if you look at the document behind the link, it suggests with a photo that this particular slop in my Altus-LT shifter is part of the "Centeron technology" and I can confirm this to be the case - the shifter is asymmetrically constructed, rear side having a very simple mechanism allowing for a bit of slop.

What I'm trying to ask is probably this: are these levers a likely cause for poor shifting with a non-"Centeron" rear derailleur?

And, well, answering my own question:

Shimano Bicycle System Components (1982) page 86

Shimano suggests these should only be used with a matching rear derailleur. I'll get some normal friction levers and try with them.

T-Mar

Shimano's original Centeron system, developed circa 1978, used free-play in both the levers and rear derailleur, to allow the chain tension to centre the derailleur under the cogs. The free play in the rear derailleur was achieved via a special linkage, rather than a floating pulley. First generation 105 (aka Golden Arrow) is not a Centeron design and to work properly both the shift levers and rear derailleur should be Centeron compatible.. The first generation Centeron system has more play (~1/4") built into it than the later Centeron pulley. It worked well in it's intended application (i.e. noiseless, auto-feathering system for novice cyclists) but it wasn't an indexed and you had to get the shift into the tolerance range of the Centeron system for it to work properly. Still, it was a valuable lesson in their quest for a reliable indexed system. The Centeron principle was arguably the key to the success of SIS, though, in it's subsequent, simplified form.

Ideally, you'd want to employ a Centeron compatible rear derailleur but these were restricted to entry level models. You could always try installing a Centeron pulley, to see how much difference it makes. You also want to make sure the derailleur has no binding and is properly aligned. Also, ensure that chain length and tension are properly set. This should improve matters, though whether it will solve is open to conjecture.

Modern, bushless chains may cause more issues with the early Centeron system as their added flexibility may not provide sufficient tension to activate the system.

onre

Thank you for the thorough write-up! I don't intend to get a Centeron setup together, I was more curious about whether my derailleur and levers are somehow mismatched, which they clearly are. The free play in the lever makes trimming almost impossible.

The Golden Boy 

I see the bit about “coordinated movement” but nothing about “free play” in the shifter.

Even then- the idea was to get rid of trimming- again, not so important in friction shifting. At this time, Shimano was biding their time for the slant parallelogram patent to expire. And he Centeron pulley was a huge part of SIS working right- with Accushift there was no way the shifter, pulley and teeth could perfectly match up every time.

onre

The picture of shifter swinging wildly with the text "Free-play of the Shifting Lever"?

mgopack42 

Assist from the "page 15" link above...

crank_addict

One of the poor designs of Shimano for friction action. Rid of the floater pulley and now you're shifting 'golden'.

For index, you need the floater.

The idea of select friction or index never seemed to work.

The Golden Boy 

Because I'm good at reading!!

Sorry...

onre

No prob, and no wonder the explanation must've felt odd. I've never seen anything like this before either.

The Golden Boy 

It still doesn't make much sense for the lever to have that slop- but it does for the guide pulley. But then again, I'm not a shifter/derailleur engineer...