The Golden Wrench

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

Thursday, December 23, 2010

Happy Holidays to All!

It's been a fantastic year at the 'ol shop, so we would just like to extend our warmest wishes to you and yours during the holiday season. We couldn't have done it without you! Thanks to everybody who looks at, or contributes to the blog, visits the store, calls us with questions, friends us on Facebook, and recommends us to their friends! We're excited for the 2011 season, and we look forward to seeing you all out there riding like the wind!
And a special shout-out to our Mainguy for his contribution to our success!
Happy Holidays, and be safe out there folks!

Tuesday, December 21, 2010

Preparing a Frameset for Building

When building a bike from the frame up, there are certain preparations that should be made to the frame. When a frame is painted or powder-coated, there can be build-up left in and on the headtube, bottom bracket shell, and seat tube. Precision components can be very sensitive to imperfections in frame construction, causing premature wear, binding, and noise.

Before installing any seatpost into the seat tube, it's a good idea to remove any burrs that could scratch or gouge the seatpost.

When the manufacturer makes a relief cut in the seat tube, it often leaves big burrs.

A Flex-Hone gets put in a drill chuck and is spun inside the seat tube to clean burrs and polish the tube.

There is still some excess paint left in the seat tube, but the sharp edges have been taken care of.

The next order of business is to take care of the paint on the faces of the bottom bracket shell. With most external bearing systems these days, the slightest imperfection can cause issues.

Excess paint on bottom bracket shell.

Here is the tool we will be using for this process. This tool does two things, chases the bottom bracket threads and faces the bottom bracket shell.

The tool uses a guide that runs through the center to make sure the threads and face are cut square to the center line of the bottom bracket shell.

Since the frame is brand new, the taps go in pretty easily.

Once the taps are in and recessed within the shell, we can set the tool up with the facing mill.

The tool detaches from the tap and the facing mill snaps right in.

Always apply cutting oil to any tapping/milling/cutting operation.

The shell is 95% faced. You can see the small amount of paint still remaining in the 10 o'clock position. Once this little bit is removed, the shell will be completely faced.

After: A nice, fresh, clean, perpendicular, bottom bracket shell face.

Time to do the same thing for the head tube.

Here is the tool we will use on the head tube.

This tool will ream the inside diameter of the head tube to the correct diameter for the proper headset to fit as well as facing the top and bottom surfaces.

This tool uses a cone to center itself on the side its not cutting.

Nice looking spirals of material indicate that the cutting tool is sharp and material is being removed with ease.

Once the top is finished, the tool is flipped and the bottom of the tube is faced and reamed.

I had a pretty nice spiral of paint on this one, so I grabbed another shot.

After: A nice, clean, perpendicular, faced and reamed head tube.

The final step we will talk about today is milling the fork crown.

There is random paint build up on the surface of the fork crown that the headset race will contact. To ensure good headset race contact, we will face this, as well.

Here is the cutting tool we will use for this operation. The cutting teeth are slightly out of focus. The more important part of this tool is the blue sleeve inside. This is the guide that will make the tool cut square to the steer tube.

Again, this tool provides two functions. It mills the outside diameter of the fork crown to the proper thickness and faces the crown to provide a smooth flat surface for the race to rest.

After: A clean, smooth, fresh, square surface for the headset race to sit.

Most aftermarket parts companies highly recommend facing before installing their components; Chris King, Cane Creek, Shimano, to name a few. As you can tell, there are quite a few, fairly expensive cutting tools required to do a proper frame preparation. Usually, shop rates are fairly reasonable to have this done to your bike. It is a great idea to do this anytime you install a new headset or bottom bracket, too, if it's never been done before. Your components will thank you.

Monday, December 20, 2010

Big tires. Low pressure.

Here at Freewheel during the snowy December month, we've sold more than a few Surly Pugsley's, and Salsa Mukluk's. With these bikes, come large tires that can be inflated to as little as 6 p.s.i., and up to 30 p.s.i. at their max. Our standard gauges here at the shop have a hard time reading any pressure below 15 p.s.i. so, one of our amazing mechanic/fabricators Karl devised a slick system for checking tire pressure accurately. He used a small gauge that measures anywhere from 0 p.s.i., to 30 p.s.i., a traditional pump head, and a schraeder valve that can be used for bleeding off pressure or, used to inflate the tire from any gas station or compressor. (careful, most gas station compressors aren't regulated to stop at a certain pressure, so you can easily blow up the tube. And in a 4 inch wide tire, I imagine it's not gonna be quiet.)
We've tested and re-tested these gauges to make sure they are accurate. And they are. True, an electronic gauge will read that low, and accurately, but you really can't inflate, or deflate the tube while the gauge is still attached. This slick little invention allows you to do both. Always get the right pressure for the job at hand.
Whether you're riding through 2 foot drifts of snow, or plugging along the Hidden Beach sand, you'll be able to get there safely and efficiently. It's always been a personal preference kinda thing regarding tire pressure, but this little thing will make life way easier. I swear.

We have four of these gauges for sale at the Westbank location. They are $35 each.

Thursday, December 16, 2010


Thanks for the thoughtful answers to the trivia question, gentlemen. The dramatic incident between the MAVIC guys and Mario Longhi was certainly a colorful chapter in cycling history, but Mr. Johnson had them beat (materials-wise) by over a decade! It's kind of scary to think about rolling around on a solid aluminum rim (whether cast or extruded), but he had some ideas that have stuck around. His design, if you hollow it out, is not unlike some of the modern, lightweight Velocity tubular rims.

I love Gary Klein, but he wasn't making much of anything in the 1920's. However, he's apparently building telescopes these days, and if he builds one with a Nightstorm paint job, I could be persuaded!

The correct answer was indeed Nels Johnson in 1923.

Take a look: it's pretty impressive!

The ace sleuth who dug this gem up will receive a FREE wheel building class at our posh and fragrant Midtown Bike Center, where the Lanterne Rouge sandwich will change your life.

Takumar, you somewhat anonymous fellow, contact Pete at the West Bank shop and he will get you all set up!


Wednesday, December 15, 2010

Wheels Go Round

The bicycle wheel is a mathematical marvel, a near physical impossibility in terms of strength and weight. It's all in the spokes, as they say. Building wheels, therefore, seems like it should be a straightforward, scientific proposition: put the spokes where they belong, get the tension even, and KABOOM! A shark eats it! Oh wait--that's my favorite recurring nightmare. I meant KABOOM! You've got a wheel!

Perhaps you can anticipate where I'm going: building a wheel should be a straightforward, scientific proposition, but sometimes it takes a discouraging amount of trial and error. One of our favorite SuperCustomers brought in a vintage Campagnolo Record hub (complete with an authentic patina of paleo-grime) for us to build into a new wheel. He brought in a similarly ancient Weinmann Concave rim. How ancient? Tough to say: Weinmann made a mess of them from late '70's to mid '80's. For their time, they were fantastic: they're super strong on the radial axis, fair to look upon, last for a long time, and are generally straight and round out of the box. You bet! Touring wheels! Modern wheel aficionados, however, would object that they're heavy, subject to torsional flex, and only single-wall (which leads to torsional flex).

Let's lace them up!

I measured the rim and hub, then cut me some spokes.

Then I started putting the bits 'n pieces together. Normally, I build a wheel by lacing drive-pull, non-drive-pull, drive-push, then non-drive push. It's the easiest way I know and I can do it while enjoying many of the benefits of sleep.

Not very far into the project, however, I came to the conclusion that Tullio Campagnolo and Dae-Jung Weinmann very clearly did not collaborate during the design phase of these two components. In fact, it seems they were having some sort of spat, glowering over their drafting boards, muttering tart epithets about one another from beneath knitted brows. "I'll show him, that rump-nursed stinkard," each hissed concerning the other through clenched teeth.

How could a rim and hub be non-compatible? I could never have guessed, but they pulled it off. I planned to document the build with the camera, but gave up on the pictures portion when it became clear that lacing it like a normal ole wheel wasn't going to work. How do you mess up drilling spoke holes on a hub?!? And how do you offset the holes in the rim backwards?!? Ugh.

You can maybe sort of see it in the above picture: every other spoke hole in the steeply beveled hub flange is counter-sunk, apparently so the head of the spokes can sit in the flange. Bad idea! Especially when the spoke holes in the rim were offset, but drilled the opposite of every other rim I've seen: instead of (from the valve stem, moving to the right on the inside of the rim) down-up-down, these were up-down-up. I have an old Dunelt with rims drilled that way, but all modern rims are down-up-down if they're offset at all. Combine backwards rim drilling with fiddly hub flanges... Let's just say it took three tries to get it laced where it will work, but it's tight, round, and straight, so SuperCustomer ought to be happy!

On a slightly different note, we had a hale and hearty winter warrior come in with what seemed to be a routine broken spoke on a mid-to-low budget wheel. Normally spokes give out at the elbow, but in this case...

You can see that the chain had wandered behind the freewheel and caused some turmoil. It's surprising to see a hub flange give out before a chain-chewed spoke!

Trivia Question!!!

First one to answer it correctly in the comments section gets a full-ride scholarship to an upcoming wheel building class!!! If you win, I'll have my people call your people and you'll be on your way to developing a highly rewarding skill.

The Question: Who first patented an aluminum bicycle rim, and in what year? Hint: It was neither Kermit Weinmann nor his brother Yeorgi, nor anyone by that surname. It was some other dude from not Germany and not Prussia.

Another hint: he was from Wisconsin!


The answer was Nels Johnson, who filed a patent in 1921 for a solid-core Aluminum rim. The patent was granted in 1923. Thanks for playing!

Tuesday, December 14, 2010

Like a science-fiction movie

I've noticed something over the last couple days. And the local news stories I've read tend to corroborate my hunch: automobiles are not a good way to get around the city right now.

We got enough snow over the weekend that even our formidable army of plows hasn't been able to properly dig us out yet. The average city street is at least a lane narrower than normal, the road surface is bumpy, slippery, packed snow and there are odd drifts and piles all over the place. Arterial roads are in no better shape than side streets. Traffic in the downtown core is a tangled parking lot.

Enter the bicycle. Down the middle of every multilane street (between lanes going the same direction, I mean) there is a precise bicycle-size gap that stretches like a secret back-alley through the labyrinth of idling motor vehicles. Coming home yesterday during evening rush hour, I had the surreal experience of pedaling for over a mile through a corridor of immobile cars, their taillights lending an eerie red glow to the curtain of exhaust plumes.

It felt a little like the System was breaking down. And I felt a little like I was outside the system, still able to do my thing in spite of the quiet chaos surrounding me and my bicycle. It was tranquil, that back-alley down the middle of Washington Avenue. Tranquil even though I could sense the frustration of the drivers who saw me flash past, using a part of the road that for them didn't exist.

If nothing else, maybe it changed their understanding of the phrase, share the road. For me it was, after all that, just another ride home.

Monday, December 13, 2010

Now Taking Requests!

Over the past few months we have had lots of feedback from readers of our blog. We even had a few people asking for repair advice. In light of this, we will now be taking requests. If you have a particular repair question or want to know more about obscure repairs, shoot us an email at We will try to do more write-ups this winter and you're ideas will be valued greatly.

Repairing a Stripped Pedal Thread

Occasionally we will have a customer come to us with a right pedal jammed into the left crank arm, or vice versa. In most cases, the pedal has a steel spindle and the crank is aluminum. Aluminum, being much softer than steel will accept the forced thread, but not for long. Once a load is put on the pedal the threads begin to strip out and the crank is toast! Or is it?

Of course, on lower end bikes, a left side crank arm can be purchased for a fairly reasonable price. However, right side cranks or higher end cranks can be much more expensive. In most cases a pedal thread can be repaired.

For science, I went against all of my mechanical training and experience and forced this right (Red for Right) pedal into the left crank arm. It was quite liberating.

Now that our left crank arm is good and wrecked, its time to get fixin'.

Remove the crank bolt.

Extract crank arm.

Up close of the damaged threads. if you look straight down the center, you can see where the newly forced right-hand threads cross the preexisting left-hand threads.

Left-hand in silver, Right-hand in gold. they can also be identified by the direction the threads slope. Left-hand threads slope up to the left and right-hand threads slope up to the right. Same as pedal threads.

Double check the tap to make sure you're using the correct one. The last thing you want to do it tap a right-hand thread in the left crank. This particular thread repair kit uses a special tap with a tapered reamer. It enlarges the hole and then taps the new threads all with one bit. Also, Make sure to use plenty of cutting oil to keep the tap cool and lubricated.

There will be plenty of metal shavings. The tap needs to be sent through all the way.

Pristine new threads!

Grease the pedal threads and install thread insert on pedal spindle.

Apply high strength thread lock compound to the external threads of the sleeve insert. This will keep it from being removed from the crank when the pedal is taken on and off.

Thread insert into the crank. Wipe off excess thread lock compound before threading in all the way.

There will be a bit of overhang on the back side of the crank.

The quickest way to remove this is with a bench grinder.

After the thread lock compound cures overnight, the pedal can be removed and reinstalled as if the new threads were one with the crank.

Time for reassembly.

Grease those bolts! This will allow proper torque to be achieved and protect the threads from corrosion. Park Tool's PolyLube 1000 works great as an assembly grease.

Tighten crank bolt to spec. In this case, Shimano recommends 35 - 50 Nm.

Reinstall pedal.

Here is the finished product. It's hard to tell that there was every anything wrong with this crank in the first place.

Our Shop bike is reassembled and ready for lunch trips to Chipotle once again!