Friction shifting is the key to simple versatility. As long as the derailleurs will handle the chain wrap and the largest cog* you can put any wheel in there that will fit.
*If your frame has long dropouts, you can even push the limits of the largest cog. Just pull the wheel back to make more room for the upper derailleur pulley to clear it. Good luck finding a modern frame with long dropouts unless they're track dropouts, but the concept is sound. However, there are limits. And the industry pushes them closer and closer every day.
A customer received a Ridley cyclocross bike, looks to be about a 2014, and wanted to convert it from its racy gearing to something more comfortable for a "more seasoned" rider negotiating New England gravel roads. New England doesn't do switchbacks. By the Puritan ideal, if the Good Lord placed a hill in front of you, you go straight up it and sing a hymn at the top.
The tight gearing on the bike was as low as it could go with the short cage Dura Ace derailleur. Any derailleur compatible with his index-only brifters wouldn't handle as large a rear cog as he was hoping to employ. But he's been at this for enough decades to have lots of experience with downtube friction shifters. He used them for multiple recent long distance tours where he essentially section-hiked a transcon over two or three seasons. That was on a much older steel bike which he has now replaced with a Surly Disc Trucker. But the Ridley was a gift from one of his kids who was finished with it as a race bike, and he couldn't let go of the idea that he could make it suit his needs for day rides around here.
After crunching a bunch of numbers I concluded that there was no way to make his desired setup work with those brifters. I assured him confidently that he could do anything he wanted with friction barcons. I based this on all of my own bikes, and numerous conversions for other customers. But none of them were very recent, and none of them had pushed for as much gear range as this rider wanted. The friction barcon option seemed to bypass most of the obstacles, but a new trap lay in wait.
He figured that a 42-tooth low gear cog would suffice with the 34-tooth inner chainring on the existing crankset. He would pull down the outer ring from 50 to 44. I researched rear derailleurs to find one that could handle the chain wrap and large cog. Using friction shifting, we didn't have to worry about index compatibility. It just had to haul the chain from one side of the cassette to the other.
Cable routing was complicated because they run inside the down tube. Routing on the handlebar was also complicated because the 3t bars run the cables inside the top section. While slightly less messy than running hydraulic lines through both the bars and the stem, it's still virtually impossible to feed a piece of cable housing through the holes they give you after you remove the one that used to be in there because it's too short to reach the new shifter position. So screw that, I ran the housing outside the bars, but only after wasting a couple of hours trying the feed housing through the route that 3t intended. I could have fed a cable through the old piece of housing before I yanked it, but I needed to be able to fiddle and fit the new housing to get the length just right, which would mean multiple insertions and removals. That would have gouged up the sheathing of the housing before I made the final connections.
Although the rider was not going to try to index, I used index housing in case by some miracle the indexing worked. It's also stiffer in general, which should help when hauling the chain up onto that ridiculous low cog. However, routing it under the tape takes a lot of hand strength to hold the bends in place while I secure them with white tape.
Note: Electrical tape has no place on a bike, especially on your handlebars. It gets disgusting.
To keep the route clear inside the frame, I had to place feeder sleeves so I could install and remove the cables multiple times while establishing the proper length for the housing, including the inline adjusters. Inline adjusters aren't needed for friction shifting, but I wanted them in case I got the indexing to work. They're also nice to snug up the cables to make sure that you can hork that chain up onto the lowest cog, even if the lowest cog isn't freakishly large. Your average technolemming has no appreciation for the stress placed on the parts that give them their fashionable gears on demand.
With the cable finally secured enough for a test shift, I hauled up on the right shifter. The derailleur made it to about three cogs from the lowest gear and stopped. Okay, the cable housings probably needed to settle in. Snug the cable, try again. Same result. The cable was tight. The shifter itself had reached the end of its travel well before it moved the derailleur enough to make the full spread.
The term "actuation ratio" entered the biking vernacular way back in the 1990s, when SRAM was trying to establish technical credibility after their lawsuit pried Shimano's fist slightly loose from OEM spec on every brand. It had been a factor ever since Shimano forced index-only shifting on us in 1990, but other factors obscured its importance. Even after SRAM started clucking about how their actuation ratio was more efficient, it mattered so little compared to other factors that no one considered it more than a piece of marketing hype.
It matters now, buddy. For much of the 1990s, owners of road and mountain bikes could do a fair amount of mixing and matching. Shimano and the technofascist industry hate mixing, matching, and independent mechanics. We're bad for the bottom line. Perfectly matching parts groups offer the kind of precision that the average rider craves until it doesn't work. Tell the consumer that they have to buy a complete purpose built bike for every application and the ones who can afford it will do so. However, the bike business -- as separate from the bike industry -- was a very early canary casualty in the crumbling middle class economy. That and the consumer thirst for entertainment that requires no exertion and little independent thought. Fewer people overall had disposable income and fewer of them were disposing of it on bike stuff.
The bike industry offers a plethora of categories, and models within those categories, so that the well-funded consumer can have the exact bike they crave for a given riding style. If you don't have enough money, they ain't talkin' to you.
With everything index-only and engineered to perfection, actuation ratio not only controls precision within a category, it also can now impede the friction shifting outlaw. I have to see if I can find the right combination of a shifter and derailleur to make the full span. For instance, a 12-speed barcon intended to match Shimano mountain actuation ratio pulls more cable than the 10-speed road shifter I spec'd originally.
Total cable pull is not a statistic that ever mattered. With a downtube shifter with no hard stop, just keep pulling until the chain goes where you want it. The angle could get awkward, so there's a functional limit, but not a solid curb. A barcon, on the other hand, has to work within the angle set by the bracket inserted into the end of the handlebar. The amount of cable pull is set by the radius of the cam through which the cable is inserted. No one keeps track of that specific dimension, because the "number of clicks" is the determining factor for the riders who depend on that crutch. Total cable pull just comes along for the ride.
When I chose parts for the conversion, I looked past the 12-speed shifters. I shy away from the high numbers by reflex, because I avoid the sheet metal cogs and tinfoil chains of high-count cassette systems. I've used nine-speed cogs to build custom cassettes, but nothing thinner if I can avoid it. Cog farming becomes increasingly difficult, so I have had to slip the occasional ten-speed cog into the mix if it's the only one available with the right tooth count.
Personally, I would never own anything with ten or more cogs in the back. New bike purchasers can't escape them, though. Some bikes have come through with nine-speed cassettes, but the available derailleurs for nine-speed index-only are getting cheesier and cheesier. Derailleurs in general are getting cheesier and cheesier, but the amount of metal in them drops off sharply at the lower price points where nine-speed lives now.
We had other options. Originally I had found a crank with 46-30 chainrings that would work with his brifters, but then the compatible rear derailleurs still didn't get him the low gear he was looking for. Once we ditched the brifters, we seemed to have a clear path to the giant cassette, but that led to the current complications. I looked at using the 46-30 crank again and noticed that the one I had marked didn't work with the BB30 bottom bracket on this bike. There is a BB30 model, but you have to look for it. Even then we have no assurance that it will function smoothly, because all compatibility info is geared toward making the indexing work, and nothing else.
"Screw your indexing," I say, but they're making that difficult. So what's next for the simple rider? A fleet of fixed gears each with a different pair of cogs on the two-sided rear hubs? Choose your pair of gears for the day? Or have your caddy follow you with a rack of bikes, each geared differently for the various sections of the route. Or go with the old way of hand-lifting the chain between chainrings and rear cogs, but you definitely need long dropouts for that.
Refusal of technology is getting to be as hard as keeping up with it.
The current project remains incomplete while we wait for the 12-speed shifter to arrive. If that solves the problem, along with off-label use of an 11-speed Deore derailleur, that'll be that. If not, we try the crank. Each option comes at a cost. We warned him at the outset that it would be expensive. Advised him to hand the bike off in its original form to someone who wanted to ride it the way it was. Your odds are much better converting a classic steel frame to various other purposes than they are if you start from anything later than 2010. Little by little the industry walls off whole sections of the bike -- literally in the case of internal cables and hydraulic lines. Figuratively in the case of proprietary shifting systems. You even have to worry about the shape of your chain now, because the really cool ones are directional. SRAM's even have a flat top that's apparently crucial to proper operation.
Fuuuuuuuck that shit. I feel deeply sorry for the young riders who never lived in an era of true mechanical freedom. I feel almost as sorry for the riders who did have a taste of that era who have bought the line they they need to "upgrade" to the modern ephemeral crap. I suppose the ephemeral crap serves as a memento mori, a reminder to live to the limit of your resources because neither you nor any of your works will live forever. But who can really forget that after the age of about 12, and that's if you lived an extraordinarily sheltered life. We spend most of our lives with an awareness of fragility and death. We don't need another reminder, fed to us through predatory capitalism.
I suppose that the industry might actually be operating with its old naivete, desperately trying to engineer its way out of the craphole that it engineered itself into. Manufacturers have earnestly tried to improve the machines all along. It's just that cycling has split into such divergent styles that the different species can no longer crossbreed. The original mountain bikes were descended from bikes. The modern mountain bike is descended from motorcycles. The genres have nothing to offer each other anymore. They share some characteristics like pedals and a sort of general configuration, but that's all.
No comments:
Post a Comment