On the bike that kills front derailleurs we installed a Shimano Sora 9-speed compact crank. Brand new. Fresh start. The bike now shifts perfectly, according to the owner, who retrieved it and test rode it a few days ago. We're on to new crises now.
Our illustrious leader got his Shimano Ultegra rear derailleur to shift successfully on a SRAM 12-32 cassette, launching us on a little spree, defying compatibility recommendations. A customer venturing into hill climbs from her familiar realm of triathlons got the 12-32 treatment. The Zipp 404 wheel on which we put the cassette functions very well on her Surly Pacer and extremely adequately on her Serotta. Who woulda thunk it?
Showing posts with label The Bike that Kills Front Derailleurs. Show all posts
Showing posts with label The Bike that Kills Front Derailleurs. Show all posts
Sunday, August 05, 2012
Monday, July 30, 2012
More unholy experimentation
Moving from approved and tested treatments to experimental therapies on the Bike that Kills Front Derailleurs, I wondered if the 9-speed SRAM PC 951 chain might fit just loosely enough on the FSA chainring to get sideways and jam there. The ring was technically only for 10-speed systems, which is a bummer if you're one of the poor saps who bought in when 9-speed was state of the art. Would a 10-speed chain work on the cassette?
Yes it would. The 10-speed Connex chain I slapped on for a test shifted perfectly well on the 9-speed cassette. It also jammed on the chain ring at least as badly as the 9-speed chain I removed.
Okay, let's go the other way. Maybe the floppy, sloppy fit of an 8-speed chain would allow it to slide off the chainring without a hitch. But would it fit the 9-speed cassette?
The 8-speed chain shifted and ran almost perfectly on the cassette, but jammed on the chainring as badly as the other candidates. It was only sluggish shifting between one set of cogs on the cassette, requiring just a little extra nudge at the brifter.
Ten-speed cassettes are probably more finicky about chain width. And of course Shimano now has its asymmetrical chains and drive systems supposedly requiring them, in case you want to give them a tighter grasp on your cogs.
I'm sticking with 8-speed chains and friction shifting.
Yes it would. The 10-speed Connex chain I slapped on for a test shifted perfectly well on the 9-speed cassette. It also jammed on the chain ring at least as badly as the 9-speed chain I removed.
Okay, let's go the other way. Maybe the floppy, sloppy fit of an 8-speed chain would allow it to slide off the chainring without a hitch. But would it fit the 9-speed cassette?
The 8-speed chain shifted and ran almost perfectly on the cassette, but jammed on the chainring as badly as the other candidates. It was only sluggish shifting between one set of cogs on the cassette, requiring just a little extra nudge at the brifter.
Ten-speed cassettes are probably more finicky about chain width. And of course Shimano now has its asymmetrical chains and drive systems supposedly requiring them, in case you want to give them a tighter grasp on your cogs.
I'm sticking with 8-speed chains and friction shifting.
Saturday, July 28, 2012
Sacerdos ab ordinario, rite confessus,...
One of our chronic problem customers has been destroying front derailleurs at a rate of about one a month since April. The first one was simply old. It had been on his bike since about 2005. He rides a lot and, judging by the look of the bike, without finesse. But something more persistent seems to plague him.
This bike was supposed to be his fresh start after he beat his old hybrid into the ground. It's a Fuji Roubaix, a moderately decent road bike. He's had to replace wheels. He trashed a carbon fork. He was plagued by flat tires for the longest time. He's had shifting problems. As annoying as the endless series of mishaps and accelerated wear and tear has been, we could generally find cause for effect. Until the Plague of Front Derailleurs, that is.
By the end of yesterday, an hour after closing time, I had looked up the Rite of Exorcism on line. I'd thrown everything else at the bike. I was ready to dump some major Latin on it. Then I saw it was 15 pages. Fun's fun, but that's a lot of "...aut saltem corde peccata sua detestans, peracto, si commode fieri possit, Sanctissimo Missæ sacrificio, divinoque auxilio piis precibus implorato, superpelliceo et stola violacea indutus, et coram se habens obsessum ligatum, si sit periculum, eum, se et astantes communiat signo crucis, et aspergat aqua benedicta, et genibus flexis, aliis respondentibus, dicat Litanias ordinarias usque ad Preces exclusive..." And so on.
At least we finally got to see what he's doing to mangle his derailleurs in his own unique way. The first one had broken at the front of the cage so it could not push the chain effectively. The second one went the same way, but also had the outer plate of the derailleur cage peculiarly bowed outward. The third and fourth derailleur have also had that peculiar outward bend to the outer cage plate.
The rider had neglected to mention, and the bike had failed to show us on any test ride until yesterday, that the chain was hanging up on the outer chainring when downshifting under load (his standard MO, apparently) and getting dragged up into the derailleur. Each incident progressively spreads the cage more and more until the bike will barely shift.
But here's the kicker. We have now changed absolutely every component involved: front derailleur, chain rings, chain, bottom bracket bearings, everything. All brand new. Chain still jams.
ADJÚRO ergo te, omnis immundíssime spíritus, omne phantásma, omnis incúrsio sátanæ,...
I might just resort to the Holy Sledge Hammer and call it good.
This bike was supposed to be his fresh start after he beat his old hybrid into the ground. It's a Fuji Roubaix, a moderately decent road bike. He's had to replace wheels. He trashed a carbon fork. He was plagued by flat tires for the longest time. He's had shifting problems. As annoying as the endless series of mishaps and accelerated wear and tear has been, we could generally find cause for effect. Until the Plague of Front Derailleurs, that is.
By the end of yesterday, an hour after closing time, I had looked up the Rite of Exorcism on line. I'd thrown everything else at the bike. I was ready to dump some major Latin on it. Then I saw it was 15 pages. Fun's fun, but that's a lot of "...aut saltem corde peccata sua detestans, peracto, si commode fieri possit, Sanctissimo Missæ sacrificio, divinoque auxilio piis precibus implorato, superpelliceo et stola violacea indutus, et coram se habens obsessum ligatum, si sit periculum, eum, se et astantes communiat signo crucis, et aspergat aqua benedicta, et genibus flexis, aliis respondentibus, dicat Litanias ordinarias usque ad Preces exclusive..." And so on.
At least we finally got to see what he's doing to mangle his derailleurs in his own unique way. The first one had broken at the front of the cage so it could not push the chain effectively. The second one went the same way, but also had the outer plate of the derailleur cage peculiarly bowed outward. The third and fourth derailleur have also had that peculiar outward bend to the outer cage plate.
The rider had neglected to mention, and the bike had failed to show us on any test ride until yesterday, that the chain was hanging up on the outer chainring when downshifting under load (his standard MO, apparently) and getting dragged up into the derailleur. Each incident progressively spreads the cage more and more until the bike will barely shift.
But here's the kicker. We have now changed absolutely every component involved: front derailleur, chain rings, chain, bottom bracket bearings, everything. All brand new. Chain still jams.
ADJÚRO ergo te, omnis immundíssime spíritus, omne phantásma, omnis incúrsio sátanæ,...
I might just resort to the Holy Sledge Hammer and call it good.
Subscribe to:
Posts (Atom)