The Golden Wrench

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

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.