The Golden Wrench

A blog about bicycle repair and maintenance by the mechanics at Freewheel Bike.

Tuesday, March 30, 2010


I spotted this rare gem at the Como Zoo. It's an old Pro-Flex Attack LE, probably 1996 vintage. A quick inventory informed me that everything on this steed is original. It has been retrofitted for trailer duty and has probably not seen off-road action since its first couple of days in operation. "How do you know that, mister smarty pants?" Those tabs that form the pivot behind the BB shell are teensy little things, goobered up with 6061 TIG welds, and probably re-aligned by hand after heat treating warped them out of functional alignment. Can you say "stressed aluminum?" Hopefully the owner won't be doing anything more drastic than bouncing down a few curbs between now and retirement. Most riders who ended up with one of these traded up to a real suspension bike right away, as the Pro-Flex only yielded about 1" of travel under optimal conditions. Optimal conditions for full travel included such variables as: ambient temperature above 70 degrees Farenheit; relative humidity below 46%; rider's body positioned so that 80% of his weight was directly above the rear axle; rider's middle name contains no unpronounced letters (as in "Geoffrey"); terrain consists of rolling hills and gentle corners, with no slopes exceeding 15% grade; soil composition less than 20% decayed material; absence of mythical beasts such as manticores, harpies, dryads, cool-headed Irishmen, and the like; and so on. These conditions were to be listed in the first appendix in the Pro-Flex manual, but to cut printing costs, the appendices were omitted from the final version of the manual.

Much has changed since 1996. I was recently putting together a new race bike that packed more technology than that bucket of bolts that took Buzz Aldrin to the moon. The frame alone was billowing tech so profusely that many of the other mechanics swooned to the floor. [We took this opportunity to hose them down with Tri-Flow and tell chimpanzees that they were smuggling bananas under their clothes--haven't you always wanted to do that?]

You would think that with all the technical advances coming out of the war rooms of the bike world, the little stuff wouldn't get overlooked. Engineers who are in charge of small frame parts would look at the new tech specs from component makers and what not. That's a safe assumption, right? That's the type of thinking that the crew of the Minnow engaged in before their fated three hour tour.

This is a rocket frame from a household name in cycling, and that is a brand new Deore XT derailleur. That pin on the aforementioned derailleur is hanging on for dear life to the little tooth on the derailleur tab, waiting for the first available impact to send the upper pulley into the cassette. Perhaps there will be no problems, but this is a RACE BIKE. It's designed to be pummeled mercilessly by skinny, leg-shaving dudes who can put out 250 watts for two hours straight over terrain that would lame a goat! This part will likely receive a beating the likes of which rented mules have rarely seen! And I'm a pessimist (as if you couldn't tell)!

Perhaps, again, there will be no problems. This machine might end up with a trailer behind it and never see more chain slap than that which occurs from dropping curbs slowly. The Pro-Flex has managed to survive this long (fifteen years!) without losing its rear end after all.

We really love engineers and appreciate their labors. Some of our pets are named after famous engineers (or maybe it's the other way around) (my dog is named after one of Saturn's moons) (OK, done sharing). Maybe the engineers at this particular company weren't getting along, because this sort of thing should be caught in house.

Sunday, March 21, 2010

Mastering the Art of the Non-Lumpy Wheel

Spring has sprung here at Freewheel. Spring means only one thing to Freewheel Service: a list of new things. We saw new faces (welcome, Adam and Nick!), new fonts on our shirts, new presta chucks, new jaws on one of the truing stands, and new technology. We recently had a training session about how to balance spoke tension in a wheel by using a computer-generated graphing program. As is the case with just about everything in life, balance is the key. A few stresses not countered by equal and opposite stresses can make your life look like a Pringles brand baked potato crisp faster than you can say "a registered trademark of the Proctor & Gamble corporation, all rights reserved." The same, it just so happens, goes for wheels. A wheel may look round, sound round, smell round, taste round, and give off a roundish sort of aura, yet its soul may look like this:

Anguish and despair lurk insidiously in those little peaks of blue and crimson: what the graph is illustrating is the tension in every spoke on the drive side (red) and the non-drive side (blue) of a standard repair wheel from one of our suppliers. The soon-to-be-legendary Karl went through a handful of stock wheels and nefariously fiddled with the spokes in order to whack out the wheel's tension balance while keeping it straight. Is a straight wheel a good wheel? The wheel represented by the graph was pretty straight in the stand, but the wild fluctuations in spoke tension predicted that the customer would be back with an angry countenance and a Pringle-shaped wheel if he rode the bike at all.

We could just blame the customer for poor technique I suppose.

Shop Guy: "Charlie, you're eighty-four and a veteran of two wars. You've killed a rabid black bear with the tweezers from a Swiss Army knife. You performed a successful emergency appendectomy on yourself. You taught all the robins in your neighborhood to sing excerpts from King Arthur by Henry Purcell. You built a tugboat out of your old Caprice Classic after you went car-free. Haven't you learned how to ride down a curb properly yet?"

Charlie: *sigh*

And you know how it works: happy customers tend to smile quietly to themselves while angry customers send telegraphs to everyone they know. Soon customers would rather eat icelandic cuisine than come to your shop for service.

So we learned how to fix them using ingenious tools such as tension gauges, computers, Girl Scout Cookies, diet 7-Up, napkins, compressed air, and abundant tomfoolery. Since pictures are worth 1,000 words according to conventional exchange rates, and since Pete managed to take some dandies, I will let them tell the tale.

A few faceless Freewheelers kibbutzing shortly after close. The calm before the storm.

Nick and Mark chasing the spikes away. Notice Mark's custom embroidery.
We were all quite fond of it; quite fond indeed.

Adam beardedly and Trek-hattedly measures tension on the drive side of a stock wheel.

Pete gave out some luscious Girl Scout cookies at the end of the meeting.
Here is your author about to toss one in the boiler.
Tyson (yellow shirt) is actually kneeling in this picture.

Don't let Karl's relaxed posture fool you: he strikes like a cobra.

Patty mans the computer.
Bryan closely scrutinizes the tension.
Graham offers high fives at discount prices.

What is the recommended spoke tension range in KGF for a Mavic Ksyrium Elite front wheel?
The first person to e-mail the correct answer to peteh@freewheel wins this hat and candle holder.

3/26/10 We have a winner. Thanks for playing.

Friday, March 19, 2010

Trek Speed Concept Bike

Be one of the first to get a sneak peek at Trek's new Speed Concept bike. On display at our West-Bank location for the first four days of our Open House Sale.

Thursday, March 18, 2010

We're Looking For A Few Exceptional Mechanics

Here's your chance to become a Golden Wrench. If you want to work in a service department that is quality driven then we want to hear from you.
Ideal candidates will have few years of experience working in bike shops or have professional training from Barnett's or UBI. Required traits are an eye for detail, pride in your work and a desire to master your trade. Openings are for either part time seasonal or full time seasonal.

If you want to become one of the best, send your resume to

Tuesday, March 16, 2010

Galvanic Corrosion

This aluminum bottom bracket has been turning to dust inside of a titanium frame. Anti-seize would have acted as a sacrificial annode and saved this expensive component.

Saturday, March 13, 2010

The Bonk of the Soul

Spring is rough in the bike industry after a long winter. It's probably rough for grizzly bears as well. They get right fat in the fall, sleep like loaves through the winter, wake up all skinny in the spring with some breath let me tell you, and BOOM! FIVE MILLION CUSTOMERS, ALL OF WHOM WANT TUNEUPS YESTERDAY!!! So they eat the customers.

This is why customers have stopped going to grizzly bears for tuneups. They are tired of being eaten. A good customer service motto would go something like this: In the springtime, do not eat the customers. They will tell all their friends that you are grizzly bears and take their business elsewhere. That would pop on a coffee mug.

We had several zillion customers come in today who requested that we engage in various activities such as fix their bikes, sell them things, hunt for ancient hub cones, nurse a few more miles out of their ramshackle winter rigs, and explain the difference between UG and HG chains and why the big blue S changes its mind all the time. Not to mention normal shop activities such as deciphering layperson-speak over the phone, marveling at marvelous things (if you're too busy to marvel at marvelous things, you're too busy--another excellent motto), and giving Pandora the occasional thumbs-down. By the end of the day, we had all begun to drift toward the limits of sanity.

The general manager, whom we'll call "Jacques" to partially conceal his identity, was sitting on the floor behind the parts counter. He was furiously eating a slice of pizza with a hollow and hunted look in his eye. This was probably the first break he'd had in four hours.

One of the sales guys, whom we'll call "Whatsisname" because I can't remember who it was right now, stood motionless in front of the suspension bench for about a minute before admitting that he had forgotten what he had come back for. I complimented him on his convincing thousand-yard stare, noting that he was nearly translucent. Despite his haggard countenance, he responded crisply in the King's English, forming what most certainly was a sentence, and probably a good one at that. I was using my resources to frantically check sold bikes over for customers and could not use my brain to process incoming verbs and nouns. I got the prepositions and a few adverbs such as "to" and "by" and "swiftly," by which I think he meant that customers were waiting and I ought to work faster.

I was installing a rack with lots of fiddly bits which was designed by people who smile and laugh and play lots of Frisbee in the cool grass, having had an excellent lunch, and who often knock off work at 3 PM to go mountain biking in real live mountains, which are right out the back door of their offices, those offices being stocked with pinball machines and tanks full of tropical fish. As I mused about the designers, fiddly bits of their latest masterpiece were bouncing off the chainstays and into the seamless void. Apparently the guys who designed the racks have three hands, or perhaps work in teams. Or perhaps they have super powers of magnetism. Or maybe they spot-weld the fiddly bits in place between games of pinball or three hour mountain hot-laps. Or perhaps they make the tropical fish do the work.

Anyways, as I struggled, Jason (oops! I mean "Whatsisname") glided silently away to help (and not eat) more customers. He will sleep with vivid dreams, I thought to myself.

We closed down the shop in high spirits, but had begun using hand gestures and shorter sentences without relative clauses (which look like this) to communicate with one another. We had come to the end of ourselves and prevailed. We can do it! More than one veteran of spring rushes said "Game on," and more than one greenhorn was trying to look brave in the face of the hurricane.

Is it going to be worse on that first 70 degree day in April? Probably. We'll be toughened up by then. Of course, at the end of the day, we'll still be running on fumes, grunting and waving at one another, laughing out loud at stupid things, and fighting off the gremlins which make us drop our tools. But we'd do something else if we didn't love it.

Pete on his laptop, burning the closing time oil
Notice the slight hunch in his shoulders
Methinks he could use a hug

Tuesday, March 9, 2010

Bicycle Repair Classes

If there is one thing that I love more than working on bikes it's teaching people how to work on bikes. That's why I love teaching the repair classes at our Midtown Bike Center. My favorite class is wheel building.
There are usually three to four people in a class. On the first day we lace the spokes between the hub and the rim and start getting the spokes tight. The second day is the hardest. We have to true, round and center the rim. Then we stress the wheel to relieve tension on the spokes which allows them to unwind. Then we add a layer of tension and repeat, and repeat, and repeat..... You see, in order to build a good wheel you have to add many small layers of tension and this can become tedious to some. During this process we constantly check spoke tension with the Park Tool TM-1
At some point we determine that we have reached an acceptable average spoke tension, usually around 100-110 kgf. It's at this point in the class that I break out the Park Tool Tension Conversion Calculator and the students kinda groan, roll their eyes and polity excuse themselves from class. You can't imagine how excited I was in the last wheel class when my solo student, Frank, stayed with me the whole way. We even tension balanced his wheel! He said he was some kind of engineer, mechanical engineer maybe, which might explain why he didn't mind graphing out spoke tension then manipulating different spokes to get them all closer to the same tension.
Frank built up a Shimano FH-M756 hub with DT 2.0-1.8 spokes and a Stan's ZTR Arc rim. Here is what the spoke tension looked like in Frank's wheel before we started balancing the tension:

We followed the tension balancing instructions from Calvin's Corner and ended up with spoke tension that looked like this:

After four tries Frank still had one spoke one the non-drive side that was too tight. Luckily he owns a TM-1 and a wheel truing stand so that he can finish this at home (balancing spoke tension takes a lot of time).

A wheel with well balanced spoke tension will stay true longer, spokes will last longer and the rim will be less likely to crack. This is why so many people demand hand built wheels.
At Freewheel Bike we offer a wheel building class about once a month. We have parts for you to use in class so that you don't have to buy the parts or you can bring your own. If you want a wheel built and tension balanced but don't want to do it yourself we offer the Pro-Wheel Build at both locations for $70 a wheel.

Be the first to answer the following trivia questions and win this King hat.

What is the thread pitch of a 2.0mm spoke?
What does "kgf" stand for?
E-mail answers to

3/10/10 11:35am we have a winner. The answers are; 56tpi and "kilogram force". Thanks for playing.

Wednesday, March 3, 2010

Things You Don't See Every Day

You're probably spending a lot of time riding in wet, sloppy metro streets these days. Paths, trails, the Greenway, sidewalks, parking lots are all covered with large pools of grayish-brown liquid in various stages of freeze/thaw. You really never know what's at the bottom of some of those puddles. "Is there a Kraken in there?" I often ask myself, hoping for the answer "no." Well, no Krakens yet, but that isn't to say that I haven't ridden through puddles deep enough to conceal at least a juvenile Kraken.

The worst (relatively speaking) time is when the grayish-brown stuff is just starting to freeze. At sunset, for example, when the air temperature is starting to drop rapidly enough to make you wonder if another layer wouldn't have been rad. There is that magical temperature when the earth is still warm enough to keep the grayish-brown stuff liquid, but it freezes on your bike. We had a bike come in the other day with a nice, even coat of grayish-brown stuff frozen all over it and this interesting formation on the BB shell:

You can just read part of the serial number in the reflected light. The owner took it home and stuck it in the freezer in case his bike ever gets stolen.