Friday, July 03, 2015

Devise and Conquer

A bike mechanic should do more than absorb and repeat the industry's latest technical information to keep pushing the wave of product rollouts down the long shore of history. The master of the craft knows you have to deal with a lot of other stuff that washes up in front of you after drifting derelict or perhaps breeding in the depths.

A minor challenge that has bubbled up in the last decade is, "where do I put the blinky light on this bike?"

The lights themselves usually come with various mounting options. Some of them actually solve the problem effectively. But the combination of seat height, seat bags, and other factors can make the mounting more of a token gesture. Why have an in-your-face flashing light when you end up mounting it down around hubcap level?

Yesterday I had to put Superflash lights on two low-priced bikes with sprung seats and suspension seatposts. This is a combination that makes on-bike mounting difficult, especially with the trend for frames with low stand-over clearance. The suspension mechanism on the post and the thickness of the cushy saddle mean that the solid part of the seat post may be buried in the frame. Even if a bit of it shows, it may be so low that the light is practically eclipsed by the rear tire.

Your average blinky user will not clip it to their clothing. That's too much to remember. They want the light on the bike. There it will remain, while its first set of batteries dies, bursts and destroys the circuitry. So I should not care whether the light is in the best possible location. But I can't help trying to do things in a neater, more functional way if I can.

After studying the bikes yesterday I realized I could take a bolt out of the seat spring assembly on the left side and devise a mounting point that would take the seat stay clamp provided with the light.

Step one: longer bolt. The nut has a step on it which will engage the hole in a washer that will form the top of the mount.
A metal washer and a rubber faucet washer go on the bolt next.
At this stage the bracket is assembled with a section of aluminum ski pole, a bottom faucet washer, a bottom metal washer and a nut to hold the whole thing together.
Here is the light bracket in place.
It's Superflash!
And there you have it. Ready to blink.
 
The rear rack limits how low the seat can go with this rig, but that would be as true with any other seat post mount. Mounting to the seat stay just puts the light down in the ground clutter.

Not a momentous accomplishment, but a nice little craft project.
 
 
 
 


Friday, June 19, 2015

If we like you, you get zip ties

Does this look like a lot of zip ties to you? Big G packed this bike about a year ago for a customer who was moving back to Santa Cruz, CA, after a few years working in the Boston area. The customer had always been friendly and appreciative. Big G went all out on the swaddling and securing.

The customer decided to bring the bike back here and buy a new one for out there, so he never unpacked it. It will stay here for visits back east, to the in-laws.

Here are all the zip ties I removed from the bike:
It seemed strangely interesting that these basically disposable items, which we had already salvaged from new bikes we were unpacking, had traveled all the way to California and then returned to us, still in re-usable condition. They've logged more miles than I have in the past 12 months.

The bike had some fascinating mold on it. I wished I had a camera that could capture the details of the microscopic Dr. Seuss forests scattered around on bar tape and brake hoods. It was even growing on the frame and the broad spokes of the Mavic wheels.

Some days my job is just so darn interesting. Right?

Bike Mechanic Retirement Home


Monday, June 15, 2015

Customers do the darnedest things, part 3,657

"There's something wrong with my brakes."

Look closely at where the barrel adjuster for the lever has ended up.

The rear tire was weirdly worn only on one side, like it would be on a car with bad alignment. We finally figured out that the intrepid young rider had been foot-braking against the tire to make up for the lack of a functioning rear brake.

Here's the front quick-release on the same bike:
Neither wing-nutted nor closed correctly, it was jammed up tight with the handle sticking out like that. You can just make out the mangled spring sticking out by the fork, too.

If you ever needed proof that bicycling is basically a safe activity and that humanity is bizarrely protected from the consequences of its own thoughtlessness, here it is. Disaster did NOT occur. Eventually, they got the bike to the bike shop and the nice mechanics made everything all right. No problem!

Your results may vary, of course. Having things properly connected is always a better idea than just stuffing it together in some vague approximation. You could be the unlucky one who actually has something come apart so badly that you're in no shape to enjoy the lawsuit afterward.

Tuesday, June 09, 2015

Tool tip, tiny tap handle

Over the weekend I had to reattach the directional cable roller for the front derailleur, on the lower rear side of the seat tube on a guy's Ridley cyclocross bike. Top-routed cables, whoopee.

The roller had fallen out and fallen apart while he was riding. He actually managed to find all the pieces and bring them to us.

The original bolt was now too short to reach the surviving threads in the riveted insert pressed into the carbon fiber frame. As the roller had jiggled and jostled its way out, it had reamed the threads at the outer end before it managed to depart. Before I stuck a new bolt in there, I wanted to freshen up the threads. But a tap handle would never fit in the space so close to the seat stays. But that spoke wrench would. I've used the trick in other close-clearance areas as well. You don't have a lot of leverage, but if you're just cleaning things up to make sure your bolt threads in smoothly and straight, you don't need a lot of leverage.

Exploding Spokes

The season of urgent repairs has arrived. People come to town for the weekend. Something goes wrong with the bike. They plead for emergency care.

Last Thursday it was two guys carrying a Specialized Secteur. It was 4:30 p.m. The shop would close in one hour.

"The bike was hanging in storage all winter," said the owner. "When I brought it out, a bunch of spokes were broken in the rear wheel."

I asked about the usual things: could a car have hit it, could a heavy object have fallen against it, do any people have access to the storage area who might be pissed off at him? He dismissed each of those possibilities. That left us with four broken spokes on the drive side, cause unknown.

The owner said that the bike had been hanging by the front wheel from a storage hook, in an unheated space during last winter's phenomenal cold spell in Boston. I had never encountered spoke failure due to cold, but there's a lot I haven't encountered. Still, I would have expected the rim to fail before the spokes. Or, more likely, the rim would contract more than the spokes, relieving tension on them.

I said I could not adequately investigate this mystery in what remained of the day. I would need a few hours to see if this thing would be safe to fly, even with the broken spokes replaced.

The spokes were all in a row. The rim is DT. The spokes are DT. The hub is one of those Specialized-labeled ones that look like they say SIXE if you read them upside down. It's "Axis." They've fixed the font now, but I liked it the old way. I can't remember what I read about those hubs, whether they're DT or Formula or some other generic maker. No matter.

The spokes had not broken at the bend or the threads. They had snapped somewhere in the middle. The edges of the breaks showed no pinching, as they would if a cutter had been used.

A cruise through the Internet turned up some forum posts about bad OEM spokes of Asian origin a few years ago. I had seen failure of various OEM spokes myself, but never DTs. Another forum thread mentioned corrosive environments that weakened spokes. The spokes on this bike did show signs of that. They had a black finish. On close examination you could see cracks in that, and some crusty residue. I sanded away the black around one, carefully and gradually, to see if the crack extended into the metal beneath. In my test area it did not appear to.

I determined the proper length for replacement spokes and installed four. Put the wheel on the stand and tensioned the new spokes. Straight, smooth, round, the wheel looked good. I stepped away to work on something else before I put the bike back together.

BANG! A black spoke snapped, sending the nipple-end across the room.

That's annoying. Glad I didn't have my eyeball down there, sighting along the truing stand calipers.

To me, that was the end of any stop-gap repair. This wheel needs to be rebuilt. To complicate the problem further, the non-drive-side spoke holes in the rim all showed little stress bulges. Nothing had cracked yet, but it made the rim a questionable candidate for the investment of parts and labor to respoke it. I don't know why the non-drive side would show stress that the drive side did not, but this wheel was clearly weird.

BANG! Another spoke fired off. That's it. This thing is dead. I took our spokes back out of it and set the remains by the rest of the bike, with some cloth draped over it as blast matting in case any other spokes decided to blow. It was less likely now that the tension had been reduced. Still, I didn't want any of us to have to dig a spoke fragment out of our leg.

While the front wheel had not misbehaved at all, its spokes had been in the same environment as the rear ones, and there are only 24 of them between the rider and a screaming face plant. Low spoke count wheels are technically strong enough for the stresses of performance riding, but they sacrifice most of their margin of safety by putting more and more load on fewer and fewer parts. When one part fails, the structure deviates much more than it would if more parts were carrying the load to begin with. Are you really going to rip down some exhilarating descent, congratulating yourself on the money you saved by not rebuilding or replacing that front wheel?

Not my decision. I did advise the owner to think about getting both wheels redone or replaced. Because he claimed -- as do they all -- that the bike barely had any miles on it, he was going to take up the matter with the shop where he bought it.

Barely any miles. Not that old. We hear that all the time. Your average ten-year-old bike is between fifteen and twenty years old. A guy brought us his 15-year-old Cannondales on Sunday, and they are 23 years old. Bikes we "just tuned up" show up in the repair records from two years ago.

Sunday started with barely enough work for the number of people on the schedule. We did not get a wave of check-ins, but the couple we did get kept us turning wrenches and looking useful until closing time. Summer has shrunk from the cheerful chaos of the 1990s and early 2000s to a brittle, somewhat desperate couple of months at best, starting on the Fourth of July weekend and not quite making it to Labor Day. But the warm weather can bring us little waves of business any time from now until the fall foliage fades.

Thursday, May 28, 2015

Your friends might not know how to tell you...You've got GRIP GUNK

"Greg's an okay guy."

"Yeah, but have you noticed? He's got Grip Gunk."

"Ewwww! No!"

That's right, riders. Spend long, sweaty hours grabbing onto those handlebars? Put in your miles, come rain, shine, or sweltering summer heat? You could be developing grip gunk.

Take our man Greg, here. Loves his bikes. Rode the rear rim on one of them literally to pieces not long ago. He's a guy you'll see out along the highway, day after day, on one or the other of his trusty mountain bikes. And he's built up the gunk. You would not believe the olive-green, greasy paste that permeated the old grips, ground into the creases, even sliming up the insides of them from dirt and sweat that had slithered in there over the years.

Gross does not even begin to describe it.

Grip gunk: don't let it happen to YOU.