As you may recall, Jake the Satanic Serpent absolutely refused to shift into the lowest gear on the rear cassette. Based on the noises from the inaccessible interior and the way it acted like it had too much and too little cable tension at the same time, I wondered if the cables had been run correctly when the bike was built. If they had somehow gotten tangled with each other, running a guide sleeve to install new cables would simply replicate the error.
With a bit of time to think about it I realized I could feel for any interference by shifting to the mid range on the rear and feeling the exposed section of cable below the chain stay as I shifted the front. There was nary a twitch.
Jake seemed strangely well-behaved today, even before I started adjusting things. The rear derailleur shifted pretty smoothly through ten of eleven cogs. But that last step, onto the lowest gear, was like a wall.
The limit screws on the rear derailleur were backed out far enough that it would start to shift into the spokes if I pulled cable tension by hand or simply shoved the derailleur over. The problem lay in the ratchet of the brifter itself. It could not pull any more cable. The rear derailleur cable was led properly, but the eleventh cog calls for tension at an angle that reduces the cable pull by just enough to prevent the shift.
If the derailleur won't go to low gear, low gear must come to the derailleur. A 1mm spacer was too thick for the lock ring threads to engage, but I had a .7mm spacer left over from someone else's weird problem. It was just enough to get the shifting to work across all rear gears from both front rings, in today's barometric pressure, relative humidity, wind speed and direction, with brand new cables and housing and everything clean.
That's as good as it gets with a lot of this ultra-modern stuff.
Jake's unfortunate owner is taking up these problems with the shop where he got the bike. I fully expect them to tell him I'm full of shit and the bike is fine.
If it comes back again, choking on silt, I'm going to drill bigger cable exit holes in the down tube by the BB. Maybe I'll cut a few big inspection ports in it, too.
Barcons, man. Eight speeds. Maybe nine. If he really wants to be competitive in 'cross, finicky brifters are just the beginning. He's going to have to turn into one of these neurotics with four different sets of sewup wheels. If that's not where he wants to go, why put up with this shit? Ah, but I ask myself that question many times a day in bike season. People believe the industry's marketing bullshit. They only have a choice of pseudo-racer tweakitude or some other very specific category. Even the all-around roadish bike has to be "a gravel bike" so it can be another freaking category.
******
High-dollar tickets often start with the words, "my friend gave me this bike." Or it might be, "my friend sold me his old bike when he got a new one," but there's always a friend. Friendship can apparently survive a lot.
The next bike after the Serpent was a Giant full suspension mountain bike, archaeologically dated to about 2004. The guy who brought it in initially just wanted to buy toe clips, a bottle cage and bar ends and install them himself. Cool, no problem. But as I looked over the bike to answer his questions I saw a few things and he began to open up about problems he had experienced with it. It wasn't shifting right. The old Avid BBDB cable disk brakes needed pads in the rear. The right crank arm was floppy loose.
Between the floppy crank arm on the drive side and the fact that the bottom bracket was crawling out of the frame, it's no wonder the bike did not shift right.
Luck was with this guy. The ISIS splined crank arm was not damaged from being ridden loose. I was able to examine the BB cartridge and crank it back in, before graunching down on the crank arm bolts with all the power of a mighty breaker bar.
Note: splined crank arms require frequent reapplications of high torque. They do not stay tight the way contemptible old stone-age square taper axles and crank arms do. Not to say you don't need to check those at somewhat regular intervals, especially after removal and reinstallation, but the square taper interface is supposed to be a press fit. Splined axles are not a press fit. So the bolt has to be tight tight tight.
Notice that the industry has basically abandoned the splined cartridge in favor of the cranks with the BB axle swaged into one side or the other of the crankset itself. This has led to its own set of problems, of course.
Once I had the Giant's BB back in the frame and the crank arms firmly attached I could start adjusting the gears. On the front derailleur I found another moving finish line: Someone had steadily shifted the limit screws on the front derailleur to chase the crank as it moved further and further out. Yep. Don't fix the underlying problem. Just move the derailleur.
Chaos is upon us. You can't look at the whole pile, only at what is right in front of you. Straighten one out, move it along. Grab the next one.
Showing posts with label Satanic Serpent. Show all posts
Showing posts with label Satanic Serpent. Show all posts
Wednesday, May 20, 2015
Saturday, May 16, 2015
Satanic Serpent
Jake the Satanic Serpent came back to the workshop about three weeks ago because the shifting had gone crunchy again after another abusive mud wallow.
"Gloucester isn't until late September," said the owner. "I don't plan on riding it until a couple of weeks before that." He was referring to the big cyclocross race in Gloucester, Mass. in the fall. He said he would be riding his road bike for the spring and summer, so not to rush the 'cross bike.
I gratefully triaged around the Satanic Serpent, grappling with more urgent repairs for people who wanted their bikes now, not four months from now. I knew the urgent work would let up at some point in the summer so I could spend the hours of brain-frying quality time the Kona would demand.
Today the Serpent's owner called requesting the bike be ready for him to ride tomorrow. And he didn't call first thing in the morning, either. It was mid afternoon and I was still finishing a repair for someone who expected it today. So at 3:30 p.m. I started on the grungy 'cross bike.
The rear shifting was all out of whack. Mere silt and grime could account for all the symptoms. With every cog the industry adds to a cassette the shifting gets more sensitive to minuscule variations in cable tension. And somehow the rider had managed to get a kink in the rear derailleur cable about an inch above the anchor bolt. This would actually come into play when shifting to the lowest gear.
The first time around I had left one piece of 4mm cable housing -- the section from the brifter to the inline adjuster -- because it was under the tape. Reevaluating the cable routing I decided to replace it with a longer section of 5 mm to move the inline adjuster from a high position near the bar to a low position. The high position had almost eliminated a kink where the housing entered the adjuster, but a much lower position would eliminate it entirely. And the new housing would be 5mm with brass ferrules, so the cable should slide more easily through it.
With all the usual rigamarole, I removed the old cable, leaving a guiding sheath in place through the down tube. I untaped the bars far enough to remove the 4mm housing and slid the old cable out of the brifter. I measured new housing, cut it, and slid the cable through it. Fed the cable through the guiding sheath. Pulled the sheath. Slid on the little chafe-guard that covers the cable where it emerges from the down tube. Ran the cable to the rear derailleur and anchored it. Then messed, messed, messed with the tension. And messed with it some more. Couldn't get it to shift up the cassette to lower gears. More tension...until it finally lifts, one cog at a time, click...click...click...and will not shift into low gear no matter what. Check the limit screw, okay. More tension. More tension. More tension. It makes the last shift.
Hit the return lever. Nothing. Three clicks to get it to drop one cog. Ratchet ratchet ratchet it down to the bottom. Ease off some tension. It sort of works through nine cogs, just gets ten. Eleven? Absolutely not. Big ring, small ring, makes no difference. It either shifts pretty badly or really badly.
I pulled the cable again to make further refinements to the housing to get the smoothest curve with no tight bends or kinks. That didn't help. Changed the chain from a KMC to a brand-name Shi-no, just in case the derailleur and cassette were particularly loyal. Another waste of time.
From the beginning, the cables have had a raspy sound and feel as they pass into and out of the down tube. The entry and exit holes are just big enough for the cable. I can't shine a light and paste an eyeball up there to see what might be snagging things in the interior. Really skinny fiber optic cameras cost some serious coin.
By 6 p.m. I was ready to use a fire ax to open it up. I called the customer about twenty minutes later to tell him he could ride it this way if he really wanted to use it now, and bring it back midweek and forget about it for a while. I need to be able to spend several hours with this piece of crap, figuring out where the drag is coming from.
By 6:30 I headed out into the cloudy evening to trudge home.
"Gloucester isn't until late September," said the owner. "I don't plan on riding it until a couple of weeks before that." He was referring to the big cyclocross race in Gloucester, Mass. in the fall. He said he would be riding his road bike for the spring and summer, so not to rush the 'cross bike.
I gratefully triaged around the Satanic Serpent, grappling with more urgent repairs for people who wanted their bikes now, not four months from now. I knew the urgent work would let up at some point in the summer so I could spend the hours of brain-frying quality time the Kona would demand.
Today the Serpent's owner called requesting the bike be ready for him to ride tomorrow. And he didn't call first thing in the morning, either. It was mid afternoon and I was still finishing a repair for someone who expected it today. So at 3:30 p.m. I started on the grungy 'cross bike.
The rear shifting was all out of whack. Mere silt and grime could account for all the symptoms. With every cog the industry adds to a cassette the shifting gets more sensitive to minuscule variations in cable tension. And somehow the rider had managed to get a kink in the rear derailleur cable about an inch above the anchor bolt. This would actually come into play when shifting to the lowest gear.
The first time around I had left one piece of 4mm cable housing -- the section from the brifter to the inline adjuster -- because it was under the tape. Reevaluating the cable routing I decided to replace it with a longer section of 5 mm to move the inline adjuster from a high position near the bar to a low position. The high position had almost eliminated a kink where the housing entered the adjuster, but a much lower position would eliminate it entirely. And the new housing would be 5mm with brass ferrules, so the cable should slide more easily through it.
With all the usual rigamarole, I removed the old cable, leaving a guiding sheath in place through the down tube. I untaped the bars far enough to remove the 4mm housing and slid the old cable out of the brifter. I measured new housing, cut it, and slid the cable through it. Fed the cable through the guiding sheath. Pulled the sheath. Slid on the little chafe-guard that covers the cable where it emerges from the down tube. Ran the cable to the rear derailleur and anchored it. Then messed, messed, messed with the tension. And messed with it some more. Couldn't get it to shift up the cassette to lower gears. More tension...until it finally lifts, one cog at a time, click...click...click...and will not shift into low gear no matter what. Check the limit screw, okay. More tension. More tension. More tension. It makes the last shift.
Hit the return lever. Nothing. Three clicks to get it to drop one cog. Ratchet ratchet ratchet it down to the bottom. Ease off some tension. It sort of works through nine cogs, just gets ten. Eleven? Absolutely not. Big ring, small ring, makes no difference. It either shifts pretty badly or really badly.
I pulled the cable again to make further refinements to the housing to get the smoothest curve with no tight bends or kinks. That didn't help. Changed the chain from a KMC to a brand-name Shi-no, just in case the derailleur and cassette were particularly loyal. Another waste of time.
From the beginning, the cables have had a raspy sound and feel as they pass into and out of the down tube. The entry and exit holes are just big enough for the cable. I can't shine a light and paste an eyeball up there to see what might be snagging things in the interior. Really skinny fiber optic cameras cost some serious coin.
By 6 p.m. I was ready to use a fire ax to open it up. I called the customer about twenty minutes later to tell him he could ride it this way if he really wanted to use it now, and bring it back midweek and forget about it for a while. I need to be able to spend several hours with this piece of crap, figuring out where the drag is coming from.
By 6:30 I headed out into the cloudy evening to trudge home.
Wednesday, April 01, 2015
Housing crunch
And so my season begins. Local rider brings in the bike he got somewhere else because the shifting went bad on him during his abusive first ride.
Kona Jake the Snake cyclocross bike. New 105 11-speed. "I read that it's hard to adjust," he said. "So I brought it to you."
"I kept twisting the barrel adjusters the whole ride," he went on. "It was never right." He added that the ride group wallowed through a lot of mud and snow.
The way the internal cable routing was done, the shift cables can't be cross routed. That would have helped with the angle up front. Either way, longer housing will feed it more smoothly into the stops. The in-line barrel adjusters need to be moved closer to the handlebars because the housing can't be led to the opposite sides of the head tube. All this could have been done by an imaginative mechanic during assembly. Now it will cost him a couple of shift cables and some new housing. As they're done now, the plastic ferrules on the constrictive 4mm housing are already kinking after about 50 miles.
This kind of rescue operation after some other mechanic's ethical lapse or simple inexperience really makes me tired. I could just dial it in as closely as I can and tell him he'll have to live with it, but I want to see if it can be improved. In terms of ultra modern bike componentry, that means, "be made to work more or less adequately for as much as a couple of months."
I already noticed that the housing for the rear cable disc brake aims upward, where it will surely collect water. So that'll be rusting in within months. But it's got eleven speeds. And carbon forks. Oo, baby. Value added.
Something sounds raspy in the impenetrable interior of the cable path through the frame. The bike came with the same weird, brown cables that Big G's Roubaix had, with some shreddy coating on them. On this bike, wads of scuffed-off coating are wedged like old snake skin at friction points in the system. Who knows how much of that is binding the new cable inside the down tube where no one can get at it.
With new cables and better-aligned housing, the shifting still won't dial in. But as you slog through the mud in your three or four working gears out of 22 (I'm being optimistic), you can rest assured your bike looks really sharp and is aerodynamically its most efficient, thanks to the internal cable routing.
As so often happens, you have to do the job to see if the job can be done. So after the extra rigamarole of a routine internal cable change I'm only a little better off than I was before. I'll know after more fiddling whether I can raise this annoying piece of crap to an acceptable level of function.
Kona Jake the Snake cyclocross bike. New 105 11-speed. "I read that it's hard to adjust," he said. "So I brought it to you."
"I kept twisting the barrel adjusters the whole ride," he went on. "It was never right." He added that the ride group wallowed through a lot of mud and snow.
The way the internal cable routing was done, the shift cables can't be cross routed. That would have helped with the angle up front. Either way, longer housing will feed it more smoothly into the stops. The in-line barrel adjusters need to be moved closer to the handlebars because the housing can't be led to the opposite sides of the head tube. All this could have been done by an imaginative mechanic during assembly. Now it will cost him a couple of shift cables and some new housing. As they're done now, the plastic ferrules on the constrictive 4mm housing are already kinking after about 50 miles.
This kind of rescue operation after some other mechanic's ethical lapse or simple inexperience really makes me tired. I could just dial it in as closely as I can and tell him he'll have to live with it, but I want to see if it can be improved. In terms of ultra modern bike componentry, that means, "be made to work more or less adequately for as much as a couple of months."
I already noticed that the housing for the rear cable disc brake aims upward, where it will surely collect water. So that'll be rusting in within months. But it's got eleven speeds. And carbon forks. Oo, baby. Value added.
Something sounds raspy in the impenetrable interior of the cable path through the frame. The bike came with the same weird, brown cables that Big G's Roubaix had, with some shreddy coating on them. On this bike, wads of scuffed-off coating are wedged like old snake skin at friction points in the system. Who knows how much of that is binding the new cable inside the down tube where no one can get at it.
With new cables and better-aligned housing, the shifting still won't dial in. But as you slog through the mud in your three or four working gears out of 22 (I'm being optimistic), you can rest assured your bike looks really sharp and is aerodynamically its most efficient, thanks to the internal cable routing.
As so often happens, you have to do the job to see if the job can be done. So after the extra rigamarole of a routine internal cable change I'm only a little better off than I was before. I'll know after more fiddling whether I can raise this annoying piece of crap to an acceptable level of function.
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