Facepalm with shifting issues

[kbmpi]

This year I've purchased a Miche Primato 8speed cassette for old 8speed campy hubs, (actually purchased last spring, but only installed this year). I've also bought a 16t cog with the cassette for the same spline pattern.

I've installed the original cassette, and put the 16t cog between the 15 and 17t, ditched the last, and I was happy for around.. 1200 km-s. (that was the time I've changed the chain from HG50 shimano to SRAM PC850, the former got elongated to the point it was noisy)

After that, the drivetrain developed a problem: i can shift anywhere, even acros 2-3 cogs without hassle, but I cannot get the chain from the 16t cog up to the 17t, only with a little extra pull on the lever, or, with a little extra pull on the cable with my hands. Or, if I just shift one, and let go of the paddle (campy ergo) the chain will be hesitating to get up to the 17t.

It'll get there "eventually", but it takes loong time. Sometimes it's only half a pedal turn, sometimes many seconds.

Troubleshooting sheet:

-RD B tension adjuster screw: tightened a bit to get more spring tension, made no noticeable difference
-RD upper pulleyx alignment with the cogs: seems perfect in all gear, but, even though it's on the right place, the 16-17transition does not work.
-RD hanger on the rear dropouts checked.. they are aligned well.
-Cable tension.. cables changed-lubricated, shifting is easier and crisper, but the 16-17t transition DOES NOT WORK If I tighten the cable to get this transition done, then I have noise in all other gears, and cannot shift towards smaller cogs..

The whole system worked like charm for years with original campy 8speec cassette, only developed this problem this year with the Miche cogs...

Is it possible that the "timing" and ramping on those two cogs are not aligned as it should be? The shifting problems started roughly after 1200-1300 km-s (after I've changed the chain from sh to sram), and I admit, I use 90% of the time the 16t..

a little video to illustrate the problem:

https://www.youtube.com/watch?v=cJS95FZN6S8

NB. if i'M on 14t and push on the paddle 3 clicks, the chain is at 17t in no time, even from 15t I can reach the 17t, but, from the 16t, it's impossible to shift to 17t.

the cassette is 13-14-15-16-17-19-21-23 just to be sure. Miche 8M sprockets. The chain is SRAM-pc850 without any wear or elongation

 

[mattr]

Is it possible that the "timing" and ramping on those two cogs are not aligned as it should be? The shifting problems started roughly after 1200-1300 km-s (after I've changed the chain from sh to sram), and I admit, I use 90% of the time the 16t..

Yes, quite possibly the ramps and timing are wrong, problem is made worse by wear, eventually it stops working. We managed with no ramps and timing in the very early days of indexing...... but it was terrible.

NB. if i'M on 14t and push on the paddle 3 clicks, the chain is at 17t in no time, even from 15t I can reach the 17t, but, from the 16t, it's impossible to shift to 17t.

The chain is already moving and bouncing around, might make it easier for it to do that 16-17 shift, rather than going from nicely seated on the 16.

 

[pigman]

Yes, interesting. I've always found, even with modern stuff, dedicated to work together, there is always one change that isn't as smooth/easy as the other changes. Once in gear, it runs well enough, but its that one shift within the cassette that is a bit "sticky" and its usually about a third of the way up from the smallest sprocket.
Dunno??

 

[kbmpi]

Re:

Thank you for the assistance.

Tomorrow I'Ll extract the cassette and measure the cogs&spacer4s, just to be sure. The mechanics in the LBS told me that probably the shifting ramp alignment is not appropriately oriented on each cog. : )

In the meantime, I should probably get a new cassette. I'M still undecided whether I'd get a 9speed veloce (and re-space it 8spd) or a 9speed miche primato.

Would the veloce worth the extra 8 euros? (30euro veloce vs. 22 euro miche)

I don't want to use 8speed sprockets anymore, as I want to prevent freehub body spline damage .

 

[foz]

was the chain already used when you put the new cassette on? If so, it has probably worn the cassette a lot more than a new chain would have - worn sprockets often don't change as well as they should.

I'd try a new cassette and chain, and see how they go. Or at least try a new chain that's the same model as the old on - I find shimano chains always work well, but can't get KMC or others to shift as well and stay as silent. Other people find the reverse is true

as the the cassette - I've had miche and campag, and would definitely pay the extra 8 euros for the campag one. quieter, better shifting, lighter... definitely worth it in my opinion.

 

[kbmpi]

nope, the cassette-chain were both new when mounted. But the chain got so elongated after 1200-1300km-s that I had to ditch it and replace with sram pc-850. I must admit, this chain is durable as hell. 5500 km-s in it, and zero elongation measured with caliper.. But the 16-17t cogs are not working properly.

As I've stated before: I use 16t 90% of the time

 

[foz]

If a chain only lasts 1200kms, then something is wrong... Unless you're riding in very bad wet weather on dirty roads and not cleaning and lubing it at all!

 

[kbmpi]

Probably the chain was faulty. The pc850 is like new after 5500 km, and i usually get out 6k from 10 speed chains on the other bikr

 

[mattr]

Could well be the measurement as well. Most tools add 2x roller wear to the chain wear. Which throws the numbers out quite a bit.

 

[BigFoz]

Re:

Why not try a new 8spd cassette - Ribble have them. The Campag cassettes have a single spline with a cut in it to force you to put the sprockets on right.

As for the chain that gels with my observations - mates with Shimano setups seem to think 1500-2000km with a chain and cassette is good going... I use 9spd veloce cassettes (steel) and a mix of chains and I get years out of a cassette on the winter/commuter bike. Only issues I've has has been with the KMC chains which have snapped (not at joining link) a lot. Am currently running an SRAM on the commuter and is a few hundred k in without issue. One of the KMCs snapped on first ride... One of the KMC chains went going up a hill out of the saddle, wrapped around the stay and bent it badly - frame was an economic write off (£400 for new back end as the ends, and both stays were gubbed.), goodbye Carlton Corsair.