Monday, July 5, 2010

Strong and Simple

I've been in maintenance mode the past few days, working on a couple of little things and two bigger projects aimed at offloading bikes.

Juliana is riding her mother's Gary Fisher mountain bike, over at her place, now that she's outgrown her little MTB. The Gary Fisher is still a little big, but Juli is doing really well on it. Unfortunately, it's been too tall at the handlebars to fit in the storage cubby at my ex's apartment, which makes the bike hard to get out of the way, over there. So yesterday, I spent a few minutes swapping the steel riser stem the bike came with for a TIG-welded aluminum stem just like the one on my Shogun -- same roll marks and everything, but no ZOOM on the side. It has a shorter quill and more acute extension angle than the original stem, so I was able to lower the bars quite a bit, which should help the bike fit both the cubby space and Juli herself.

I also needed to spend a few minutes on the Motobecane, when I discovered on a ride Sunday that the chain made a hell of a racket in top gear (big ring, small cog -- a combination I almost never use). I assumed the chain was rubbing the front derailleur cage, but I couldn't trim the noise away on the road. A little investigation on the work stand revealed that the chain was rubbing on the right seatstay tip, down where it meets the lug. I've never seen that before, but the bike was designed for a 5-speed wheelset, and I'm running seven sprockets, now. Also, the current wheelset was originally a 6-speed Uniglide that I retrofitted as a 7-speed Hyperglide, so who knows how the cog-to-frame spacing compares to the designer's expected norm. Anyway, simply shifting the axle forward in the dropouts eliminated the noise, so NBD. The seatstay tip is a little chewed up, but not too badly. It's steel, so I'm not worried about it.

But those tweaks aside, I've spent most of my labor the past couple of days on two bikes equipped with one-piece cranksets, which got me thinking about this old technology a bit more. The bikes are the Columbia balloon tire cruiser I bought last summer and promptly crashed, wrecking the fork, and a little 12" Schwinn Hotrod. They'll both be leaving my hands at some point soon, and I'll post something more substantive about the Columbia before it goes.

As to the other, I found the little Schwinn at the swap shop at the Southborough Transfer Station a year or more ago, and had planned to fix it up and donate it to a nonprofit or something. But my nephew Jack took a shine to it when he and his parents were over at the house for dinner a week ago, and I promised him I'd get it working. The little Schwinn will fit him today, where Ava's Gary Fisher (which they took with them when they left) is still a year or two too big. The Schwinn wasn't ready for him, though -- the training wheels weren't turning, the crank and chain felt pretty stiff, and I wanted to make sure the headset and coaster brake were OK -- both are pretty important. It's all set, now, and he'll get it this week.

The Columbia has had a pretty siginficant overhaul the past week or so. It's hard to tell, becase it looks largely as it did when I got it. But the changes are definitely there. Again, that's a post unto itself -- let me stick with one-piece cranks for a bit.

Most of the bikes I've put a wrench to have had "three-piece" cranks, the pieces being the left crank, right crank and bottom bracket, an example of which can be seen below at right. These cranks are from the Kestrel, which I've started disassembling (though this particular BB has been off the bike for a few seasons, now). The only one of these "three pieces" that's actually just one piece is the left crank -- the other two are really assemblies.

The one-piece crank shown above, at left, is from the trailer bike. It's a steel forging that's bent into a single shape comprising the left arm, axle and right arm, and pieces of the bottom bracket thread onto it to lock it all into the frame. On a three piece setup, the bottom bracket is a standalone assembly that threads into the frame first, and then the cranks mate to either end of the spindle and are secured by a bolt. If you're reading this blog, you probably already know this. Looking at the two piles of parts, it's easy to tell which is lighter and more refined!

Prior to taking the one-piece crankset off the trailer bike several years ago to install a three-piece unit, I think the last time I'd opened one up was in 6th or 7th grade, when I got my old banana-seat Ross working again so I could jump it over boulders at the bus stop. Then more recently, I regreased the cranks of both of Ava's bikes last year. Then the two bikes this weekend. Three of four of these were on kids' bikes, you'll note. And for me, these cranks have been inexorably linked to heavy and inexpensive bikes from older American brands -- Huffy, Ross, Columbia, Murray and Schwinn. So to someone used to working on lightweight three-piece cranksets fitted to lightweight bikes, these cranks can seem a little low-brow.

The bottom-feeding impression is really reinforced when you sit down to look at typical examples of these cranks. The bottom bracket bearings are generally not well sealed, and the hardware itself is often coarsely made. And the cranks are heavy, and often not carefully finished. The ones I've handled have all been pretty crude, with obvious grinding marks and the like. And in a way, working on them is not far removed from working on one of my Gravely tractors -- sturdy, old, unsophisticated stuff.

On the other hand, old and unsophisticated doesn't necessarily equate to bad. A one-piece crank allows anyone with a big adjustable wrench and a large flat-head screwdriver to adjust and overhaul one. These are inexpensive tools that any farmer and possibly most households would have on-hand. Servicing a loose-ball 3-piece crankset requires a crank-puller, a lock-ring wrench, a pin spanner, and if you want to take out the fixed cup, a fixed cup wrench (though often the lock-ring wrench has one of these on the other end). That's three or four specialized, relatively hard to acquire and relatively expensive tools that would serve no other purpose in the toolbox. An adjustable wrench and a screwdriver -- it's brilliant, really.

I should add that while none of the cranks I've handled have been nicely finished, there are nice examples to be found out there, and they're not expensive. And far more styling effort was historically spent on these chainrings than those on more expensive crank styles -- 4-leafed clovers, 5-spoked rings evoking muscle car wheels, hearts, cyclonic vortexes and other cool styling jobs were found on Schwinns alone. The fanciest chainrings I've seen on 3-piece cranks have been drilled extensively for lightness -- lovely, but driven by function, not form. And check out this suit of cards chainring on a one-piece crank on the Alternative Needs Transportation Boston Roadster.

The first time I saw a Boston Roadster online, I was surprised at the choice of a one-piece crank. It just didn't seem to align with the bike's price and custom nature. But I'm not so sure that's a fair conclusion, having had time to reflect on it, and having serviced the two one-piece cranks this weekend.

A steel bar forged into the shape of a bicycle crank is a heavy, but very strong thing that will survive countless bashes into curbs and tipovers onto concrete sidewalks with no more than cosmetic damage. Hammers tend to be forged from steel, too, after all. That's why these cranks are still used on kids bikes -- toughness! On reflection, there seems nothing wrong with having simplicity, serviceability and ruggedness underfoot on an expensive bike designed to provide a lifetime of errand and commuter service. And it's hard to argue that this polished chrome crank and machined aluminum chainring aren't beautiful.

There's not much that's beautiful about my old Columbia, of course, but I still think it's pretty cool. Its old Schwinn crank and chainring (at top) have seen better days, cosmetically, but they work and spin just fine, and no amount of bashing around is likely to hurt them. It's nearly ready to roll, now, and once it is, it'll roll on out to its next home. That'll leave me with only the Schwinn and Motobecane in service -- down from five. Progress!

All for now,


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