Archive for December, 2014

26
Dec
14

Okay, You Can Thank Me Now

Okay, you can thank me now.

What you are thanking me for is the fact that, rather than inflict upon my Loyal Readership the lengthy essay that I had originally written over the holidays, you are now reading a much-shorter and more photo-heavy replacement on the current state of my latest project. What almost happened here was a long cough-syrup-fueled screed about bicycle fork geometry.

Yup, a thousand or so words on bicycle forks.

I deleted it.

A short explanation: I’ve been down with the flu over Christmas and New Years, and so I haven’t worked much on Number 4.

That’s probably for the best.

In retrospect, it is completely understandable that I wasn’t able to make much progress over the holidays because, having re-read what I had originally put down, I was obviously not in a fit state to be out in the workshop. Frankly, one would have to be on some fairly powerful drugs in order to think that heeding the writer’s call and preserving for posterity my most personal thoughts about bicycle forks was somehow a good idea.

And while my memories regarding this particular winter interlude are somewhat indistinct, I do recall that pathetic, hazy, fatal moment out in the workshop when, deeply despondent, covered in phlegm, and my body wracked by coughing fits, I came to the firm conclusion that “Yes, I may be incoherent to the point where I cannot be safely trusted to attack a bowl of soup using plastic silverware and remain injury-free, let alone be turned loose on steel tubing with powerful cutting tools and a brazing torch. But, My God, if I can no longer work on my bicycle masterpiece then the world must know of the many important insights that I have concerning the gentle interplay between fork offset, head tube angle, and cornering behavior. Quick! To the computer! I must capture these golden thoughts before I tragically succumb to the dreaded grippe and my musings are lost forever!

What made it worse was that, of all the possible subjects that I could have picked to obsess about while pleasantly whacked out of my gourd on prescription strength cold medicine, one could have hoped that bicycle forks were fairly far down the list. Because when it comes to drug-fueled manifestos, holding forth on the nuances of bicycle geometry is hardly gonzo. The good Doctor of Journalism, Hunter S. Thompson, would have been bewildered. And disappointed. And bored. I could have spent my time just as productively (and far more entertainingly) holding forth on gall bladder disease in cattle.

But, no, instead it was bicycle forks.

Anyway, the good news is that the fork for Number 4 is done. And it is a beauty.

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The fork is built from components from Richard Sachs. Richissimo Crown, Columbus fork legs, and those really nice Richard Sachs fork ends.

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All of it is absolutely top drawer stuff. In terms of specs, I built the fork with a 39mm offset, which should work pretty well with the 74 degree head tube that I am planning on. The brake reach with a 700c wheel is 45mm, so it will work with normal short-reach road calipers. I’m thinking Campy Athena if this turns out as I hope it will.

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If anyone asks “Why a 39mm offset” the short answer is “Because I tried it on one of my other bikes that had a 74 degree head tube and I really liked it.” It also, interestingly, gives a figure for “trail” that appears to be within the range that Builders With Far More Experience Than I seem to think is just peachy. That is, if there are in fact hard and fast rules about things like “trail” that you should worry about.

That’s not to say that I didn’t try to figure it all out. But after a bit of diving into The Learned Treatise (i.e. the Paterek Manual) and other reading, the best answer that I can come up with is “No, I can’t actually explain why this offset works for me,” if by “explain it” you mean “I understand the basic math and science enough to construct a plausible line of bullshit about why a 39m offset yields the results that it does.” If that’s the standard, I don’t have a clue.

That’s fine for now. Given that I don’t have a lot of frames or forks under my belt, I’ll just go with what I know works for me, and I’ll tweak it as I get more experience. Plus, I’m not sure that I’ve downed enough cough syrup lately to actually feel the need to share my opinion if I had one…

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And in the Shout Out To The Readership Department: Thank you George5 at Tokyocycle.com for the kind words. Hope that I can keep you as a reader. And good luck to DeltaForce on his/her project. Some pictures would be very cool…

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12
Dec
14

A New Project, And Breaking Stuff In The Name Of Science (Sort Of)

Seeing as it has been, oh, about three months since I last updated this occasionally-updated blog, I figure that it is probably time to throw something up here lest I alienate the folks who constitute most of my visitors these days: spambots and a growing constituency of folks looking for Christmas-themed gay porn, specifically a genre of gay porn that involves guys with lots of body hair. Apparently having “Full Frontal” and “Nudity” appear in a title of a story or a post – like it does here – tends to generate a lot of hits for a website. That’s predictible. What wasn’t predictable was the respectable number of hits that you get when you combine “hairy” and, weirdly, “Santa Claus” on a website where you have also mentioned nudity. This particular combination generates a deeply disturbing amount of traffic. True fact. Apart from the story that I did a while back about repairing Campagnolo shifters, the one single post on this site that generates the most traffic is a story that features Santa and a character culled from the pages of the Performance Bike catalog known as “Hairy Catalog Guy.”

And based on the search terms that you people out in Inadvertent-Reader-Land are sending to Google in order to end up at my happy little Christmas story, I really don’t want to know what’s going on.

Anyway, the breathlessly-awaited update is this: I have another frame project. Working title for it is ….Number Four.

I know, too clever.

Bike Number Four is gonna be a bit special. The lugs and tubes were sourced from Richard Sachs. We’re talking oversized Pego-Richie tubing from Columbus, tied together with Richie-issimo Lugs and bottom bracket. The fork is from Sachs as well, with a nice Richie-issimo flat crown and curved legs.

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The best part? The box that showed up was not only stuffed with cool bike bits, it was also packed with red Twizzlers candy, a shit-load of stickers, and a signed water bottle.

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The fork is always the first thing that I build, so I’ve launched right into it. After building straight legged forks for Number 2 and Number 3, constructing a fork with a flat crown and curved legs is….different. For starters, compared to the sloping crown that I used on Number 3, the Richie-issimo crown is very traditional – a work of art.

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The crown is also a bit beefier compared to what I have brazed up before, so I really wasn’t sure if my MAPP torch had the heat huevos to tackle a crown as substantial as this. The only way to find out was to actually dive in and give it a try. The first job is to join the steering tube to the crown.

Simple.

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And I fucked it up.

Worse, I only half fucked it up, meaning that I did get it brazed together, but I wasn’t totally happy with how it turned out. Okay, I knew that it probably wasn’t going to come apart but….shit….do I want to ride a fork that is probably okay? Deciding what to do next rested upon what I call the Dirty Harry Approach to Predicting The Likelihood Of Catastrophic Failure Of Potentially Compromised Bike Parts:

Do you feel lucky, punk?

I didn’t.

Eating the cost of a new steering tube and crown was much cheaper than the likely dental bill if the joint failed. So, I decided that instead of trying to sweat the damn thing apart and try again, it was better just to buy new parts and start over from scratch.

But first, I wanted to check my work and see whether and how badly I had fucked up. In other words, a little destructive testing was the order of the day.

First test: rotational shear. Could I get the steering tube to break loose in the crown by twisting it? Stick the presumably bum steering tube crown assembly in the bench vise, get a pipe wrench and a 5 foot long cheater handle to really bring the pain, and see if I could break it.

Long story short, I couldn’t. The steering tube stayed put, even though the steering tube started to deform. So my shitty braze job was starting to look better.

Second test: impact. This one was simple. I took a sledge and tried to drive the steering tube down through the crown. Or break the crown. Either would have been cool.

Nope. After a bunch of wacks with the hammer, nothing.

By this time I just wanted to see what the joint looked like inside. So I got out the hacksaw and split the joint, fixed the now-mangled crown in the bench vice, slipped the five foot long cheater bar on the steering tube, and peeled the steerer out of the joint. Or tried to. It eventually came out after a LOT of persuasion.

The verdict: despite being fairly strong, the braze job really was pretty half assed. You can see from the pictures that I didn’t completely fill the joint with braze – there were good sized voids.

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The good news is that the replacement parts came, and this time the braze job on the steering tube was text-book perfect. Or at least I think that it is. Put it this way, I don’t feel the need to chop this one open. It’s good enough to finally make the pretty girl smile…

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