Towards Blissful shifting; what about older mechs?

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Samuel D
Posts: 2878
Joined: 8 Mar 2015, 11:05pm
Location: Paris

Re: Towards Blissful shifting; what about older mechs?

Postby Samuel D » 13 Sep 2019, 1:22pm

francovendee wrote:I've noticed that jockey/pulley wheels have become larger. Does this change make shifting better?

Don’t know about that, but it increases the length of chain tied up in the pulleys on small sprockets, which then becomes available for a greater gear range. It also marginally reduces power loss to pulley bearings.

NetworkMan
Posts: 714
Joined: 25 Aug 2014, 11:13am
Location: South Devon

Re: Towards Blissful shifting; what about older mechs?

Postby NetworkMan » 13 Sep 2019, 2:22pm

Samuel D wrote:
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.

Same cassette as I have on my tourer upthread. Smooth changing close ratios and with a 48/38/24 triple a range of 25-100 inches. There can't be many people who need anything more!

Des49
Posts: 629
Joined: 2 Dec 2014, 11:45am

Re: Towards Blissful shifting; what about older mechs?

Postby Des49 » 13 Sep 2019, 3:24pm

My training bike has a late 1980s Campag Chorus front and rear mech, still original, used almost daily unless weather is appalling. Original apart from the rear uses Tacx jockey wheels now.

Since the Campag 7sp DT lever springs disintegrated I have had to use a Dia-Comp set, I do miss the indexing and have to have the friction too tight for easy changes, yet still suffer the occasional slip up steep hills. Tempted to look for an eBay set of Simplex levers.

My memory of the sweetest gear changing I experienced was when I treated my very cheap Puch road bike in the early to mid eighties to a Suntour Superbe Pro rear mech, it just felt amazing. Though memory may be affecting actual reality!

Within a few years I was racing on Shimano 7400 7sp gear, never had a problem with that either, in fact still works great today.

Brucey
Posts: 35897
Joined: 4 Jan 2012, 6:25pm

Re: Towards Blissful shifting; what about older mechs?

Postby Brucey » 13 Sep 2019, 3:35pm

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


yes that is the case, but the rivets are not quite flush. I've not measured how much they stick out though. For many years shimano chains have had cambered outer side plates, so that even though the pins stick out slightly, they are not the only thing that sticks out.


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?


if the gap is smaller than it needs to be (esp with a single pivot derailleur) the shift can be baulky and intolerant to small adjustment errors. If you have a sprung upper knuckle then you can run a closer GPG and the shift will still go. it mayn't be super smooth but it'll go.


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.


maybe not; but the intervals in that cassette are not going to be a big challenge to shift. Part of the equation is not only how well it works, but how long it carries on working for; 6,7,8s systems have an advantage here.

Re jockey pulley size; it is probably better to have an odd number of teeth; this prevents 'every other tooth wear', and slows the overall wear rate on the pulleys.

cheers
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