Monday, December 31, 2007

The last post of 2007

Thanks to the fact that Sarah is sick AGAIN, I'm not going out tonight. It'll be some trainer riding and movie watching, and my guess is I won't make it to midnight. But honestly, who cares? The Julian calendar is as arbitrary as any other. But grumbling aside, thanks to everyone who helped make 2007 a really good year for me. Some highlights:
-Really getting into building full suspension bikes. The Ventana/Waltworks custom combos have worked out super well and I've gotten several orders for them, and my new 29" DH bike is the best long-travel bike I've ever ridden. I'm super proud of it, even if the DH crowd isn't quite ready yet (hence not one order for one... c'est la vie).
-Racing. Sarah had a great year and won the Winter Park series as an expert. Maybe she'll have to move up next year. I managed a 2nd place, a 6th place, and a 9th place in the uber-competitive Tipperary finale (you know when 50 pros roll off the line and JHK and the Schultz boys are among 'em that it's a serious race). Missed my goal of making the final podium due to a stupid DH crash. Maybe next year...
-As a side note, I was in both first place and last place at some point during EVERY race I finished at Winter Park. Not that weird, given that I usually spin out on the SS in the starts and get to the singletrack last, but still interesting.
-Sarah passed all her exams, jumped through all her hoops, finished all her classes, and is an official PhD candidate. Plus she got a raise (woo! $24k a year!)
-My good friend Lee and his wife Linda had a baby boy (congrats!) and my friends Shems and Crystal announced that they're expecting one as well. As those are my first college friends to end up in a family way, I'm feeling a little old, but I'll get over it, I'm sure.

For those of you who were waiting, here's a final shot of the Ventana frame. Shown are the shock mount and toptube/seat tube brace. I'll do a shot of the final powdercoated and assembled frame as well when it's ready.

Sunday, December 23, 2007

Happy holidays!


A big thanks to Ed for the kick-butt advent calendar, and a Merry Christmas (if that's the way you swing) to everyone! Regardless of your religious affiliation or lack thereof, enjoy some sugary treats and alcohol and I'll rap at y'all again in 2008!

Thanks to Mike M. for the picture and Steve for the posed bicicleta. I envy you guys!

Friday, December 21, 2007

Friday show and tell

Segmented forks (ie, the kind I build a lot of) have been a hot topic on Frameforum this week, and so I'm following a (newish) FF tradition and doing a "Friday show and tell". This is oriented toward fellow framebuilders moreso than casual readers, so be warned that I'm skipping some of the more basic steps in the description.

First off, a little background. I'm building this fork for Steve Garro at Coconino Cycles, so it's going on a bike for a customer of his, and I'm not involved with the frame or fork design process. Steve wants a 440mm long, 45mm rake, disc specific fork for a 180 pound rider doing all-around XC. Fair enough!

The dropouts are from Ceeway, in the UK. I buy these in huge batches because I use them a lot - and I'm happy to sell a set or two to anyone who wants to build a fork like this but doesn't want to pay $20 worth of shipping to get them from the UK. The part number is LE13-1. There's a version that will fit 25.4mm tubes as well (these are for 28.6mm) but I seldom use them. They are intended to be plugged in and brazed in place, but I simply cut the plugs off and weld them on, because it's quicker for me to do. They're cast, so the metal isn't super happy about being welded, but it works well enough.

I mount the legs and steerer up in my spiffy Anvil fork fixture - the legs are 1.2/.7/.9mm double butted (with the thick section at the top) and are made for me by Fairing Industrial. Steerer tube is a True Temper MSRDLT OX platinum steerer tube that's butted 1.6/1.1mm.

Next, I machine up some crown pieces on the mill. These ones are made from 1.125"x.049" 4130 purchased from Wicks aircraft. The fixture I made to cut every crown section at a 15 degree angle. I can make 1" pieces as well, by using a little shim shoved into the fixture. It's certainly possible to make these by hand as well, but it's a big waste of time for me, since I've got the milling machine. The crown pieces always require some deburring (as you can see) and a bit of hand mitering at the leg side to fit perfectly, but the total time required to finish them after they come out of the mill is probably <2 minutes.

I fit everything together, make sure the miters are tight, and cut off the legs at a 30 degree angle (I like the look, and this also helps make sure they don't bump into the downtube of the frame). I also drill some small vent holes in the legs, which the crown will cover up. This is to prevent the problems caused by trying to weld an enclosed space (the pressure of the hot gases inside the crown as I finish welding it would cause difficulties with blowing through as the pressure tried to escape through the molten weld puddle), and also to allow argon into the crown while I weld it.

Next, I fit some purge plugs to both the steerer and the legs, crank up the argon backpurge, and tack the fork together. I tack in 4 places, evenly spaced around each joint (for a total of 16 tacks) to make sure everything is going to stay put when I take the fork out of the fixture.

Welding up the fork (steerer joints first, followed by the crown/leg joints) comes next. The backpurge runs constantly at around 5 cfh. I weld each joint in (approximately) quarters, doing one half of each joint before swapping to the mirroring joint on the opposite side. I don't really know if this sequence is mandatory - it was the first welding sequence I tried with these forks, and since it seems to work well to keep everything straight, I'm not about to start experimenting.

I miter a disc tab (which I buy from Paragon Machine works, and use for both frames and forks) on the mill and align it using my sweet Anvil disc tab fixture, then tack (with the backpurge going once again) and finish weld. I find that it's helpful to finish weld one side (I do the left side first), wait for the metal to cool down a bit, then wire brush the opposite side to remove the nasty crud that has built up from the atmosphere reacting with the hot metal. I'm sure you could flux up the back side too, but the flux is (IMO) harder to remove, so I stick with this method.

Next I've gotta cap the legs, which is a fairly crude process. Since I'm too cheap to get a big run of caps laser cut, I just use square pieces of .032" sheet metal and braze them on, then cut/grind away the excess material. Someday I swear I'll get my act together and have some better caps made, but these work fine for now. I braze a bit of bronze onto the fork leg before putting the caps on, then hit 'em again with the torch to bind the cap solidly to the fork leg. Notice that I also braze on the crown race at the same time. The caps are held in place for brazing with spring clamps, with a little extra piece of place to prevent the clamps from dimpling them. I love how gnarly and grungy things look with flux all over them...

Finally, I file/grind off the excess cap material (you can also look at the crown/leg weld in this picture if you're one of those folks who likes to stare at welds all day) and cut the steerer to a nice even 10" (254mm, for those of you who aren't down with the SAE).


Here's a final shot of the fork. Final weight (before paint, or cutting the steerer to length): 889 grams. I'll ship her out to Steve after the holidays.

Thursday, December 20, 2007

Random picture of the day - Chris' new frame

Sometimes things just look neat. The camera didn't entirely capture it, but the coloring of this chainstay weld was really pretty, I thought. And so I decided to share it with the world. Chris, you can sleep well tonight knowing that at least one part of your bike is pretty. Let's just hope I remembered to finish welding the other chainstay, eh?

When I first started building bikes, welding the chainstays was the scariest and hardest part of the job, because chainstays are A) (relatively) thin walled, and hence easy to blow holes in, B) expensive, at least as far as bike tubing goes, C) being welded to something pretty thick (thin to thick is never easy, because one part wants to suck up most of the heat), and D) in a tight spot that's hard to see and reach with the torch. So I ruined a few chainstays before I got the hang of it. But now they're my favorite part of the bike to weld up, for whatever reason. Go figure.

Wednesday, December 19, 2007

Ian's bike - final build shot


I shudder to think what this bike weighs, but damn it's cool. I promised a final build picture - thanks to Ian for snapping this shot before leaving town.

Tuesday, December 18, 2007

Ventana pt. 2

So as soon as I got better, Sarah got sick with whatever it was that I had, so now I'm taking care of her, and things are, you guessed it, moving kinda slowly on the bike building front. What can I do?

In any case, when I left off last time, I'd just made the shim/sleeve that reinforces the seat tube around the upper pivot. Here's a picture of what I'm talking about. The back side is cut out to save a few grams (10, to be precise).

I'm not positive that this reinforcement is really needed, but it's 30 grams of insurance, and I have to shim the pivot mount to the seat tube anyway, so it seems worthwhile. In some cases (albeit not this one), this also allows me to use a butted seat tube, since the sleeve reinforces things enough that the thin section of the tube can handle the strain. In this case, though, the seat tube is too short (14.5" center to center) to use a butted tube.

Next up I braze the sleeve on using bronze - I do this instead of TIG welding it mostly because it's faster, and partially because it creates fewer stress risers than 2 TIG beads really close together. I feel that this is a safer/stronger way to make a sleeve joint like this. It's pretty much the same as brazing in a lug.


Attaching the actual pivot mount comes next. In this case I use the Ventana hardware to hold everything in place, tack, and then finish weld. People sometimes ask me if it's a problem to TIG on top of a bronze-brazed sleeve like this, and as far as I can tell, it's not a problem. I'm sure some of the bronze under the sleeve is melting as I weld, but not enough to allow the sleeve to move or to weaken the joint. Here's a close-up shot of the welded/brazed sleeve and pivot. You can see some of the flux still gunking things up, notice however that the area where the pivot is welded is cleaned up (prior to welding) to avoid any contamination problems.

Finally, I miter and tack the front triangle, then weld it up. Here's a shot of the frame prior to getting finish welds. All that's left is mounting the shock - but that'll have to be another post.

Friday, December 14, 2007

A full suspension build

As some of you know, I'm nice and sick (here's a little tip, kids - when you KNOW you're starting to feel sick, and your wife calls to see if you want to go to an all-you-can-drink-and-eat beer and cheese fest at Avery, just hang up the phone). In any case, work is proceeding VERY slowly, because it's about 25 degrees in the shop and my interest in contracting pneumonia is fairly limited. But huzzah! My loss is your gain, net-surfing cubicle slaves - I've got plenty of motivation for a long and potentially even educational blog post. Prepare to be dazzled as I explain...

How I build a full suspension frame

I do all my XC type full suspension frames using rear triangles from Ventana mountain bikes in California (as some of you may remember, I narrowly beat out Sherwood for "29er man of the year" way back in 2005). Sherwood very nicely sells me the rear triangles (along with some helpful hardware, of which I only use a little bit - more on that later) and I build custom front ends for them which have gone over pretty well with the half-dozen or so folks who have purchased one.

The first step, obviously, is to do some design work. Ventana *wants* you to use 465mm chainstays and very close to zero bottom bracket drop. While this is great for someone 6'5" who rides in really rocky terrain where pedal strikes are a huge concern, it's not so great for the other 95% of riders. Hence I usually throw the Ventana specs out the window and start from scratch. In this case, I'm doing the following basic geometry (note that the design assumes NO sag, and that this bike will have 4" travel front and rear):
Head tube: 4" at 72 degrees
Toptube: 24" effective (1 1/4" diameter), severely sloping to meet seat tube at 14"
Seat tube: Offset 10mm forward, 74 degrees (effective 73), 18.5" to top
Chainstays: 450mm (17.7") at 4.5degree drop
BB: 35mm drop (for ~13.2" BB height without sag)


So, on to building. First I've gotta miter a seat tube, but if I want to offset 10mm forward (to provide clearance for the suspension) I'll need to do something to make sure the seat tube miter all makes contact with the BB shell. In the industry parlance, we call this "ovalizing", but it's basically a process of controlled smashing using the vise and a few blocks of wood. I ovalize the bottom of the seat tube until the narrower portion is about 25mm, then miter it on the mill, along with a miter (done at the same time to make sure they're aligned) for the main pivot.

Here's a picture of the ovalized, mitered seat tube cleaned up and ready to attach.

Next up, I tack in the seat tube, and then use the Ventana rear end (in my Anvil fixture) to align the main pivot to tack as well. Here's a shot of the main pivot in position - tacking with the rear triangle in the way is a pain, but it's the easiest way to make sure everything stays in perfect alignment during the construction.

For those who worry about these things, the tube that comprises the pivot mount sucks up enough heat that there's no concern about overheating and damaging the (aluminum) shaft that holds the pivot together. I add the pivot before finish welding the seat tube to the BB because, since the miters have to be done simultaneously to keep them aligned, I would be unable to effectively backpurge the seat tube/BB welding if the pivot mount weren't in place (since there would be a gaping hole right near the weld to allow nasty non-inert gases in)

Here's a shot of the tacked joint.

Finally, the last shot of the day: the finish welded seat tube/bb area. There will be some additional bracing added to connect the pivot directly to the BB as well down the road, but this is the progress I made last night, so this is where the post stops for the day. Assuming I get healthy, look forward to another installment next week!

Wednesday, December 12, 2007

Making fun of my wife; also a recipe


I'll probably catch hell if Sarah ever actually gets around to reading this blog, but I'll take my chances. Guess who forgot her helmet at work and had to ride in her fullface? Heh.

Next up, now that I've satisfied all the bike geeks in my extensive audience: another recipe. I'm sure you've all been waiting with bated breath...

Apple-Molasses Bread (and yes, I made it up myself)
1 tbsp yeast + 1 tsp sugar + 1/4c warm H20 - proof up the yeast. If you don't remember how, you haven't been paying attention!
3c white flour, 2c whole wheat flour, 5 tbsp sugar - mix em all up.
Add the yeast to the flour mixture, and add:
1c applesauce
1 tbsp cinnamon
1/4c molasses
1c (approximately) warm water

Mix everything together, then cover in a breadpan and let rise for about 90 minutes. Bake for 30 minutes at 375, consume with gusto!

Sunday, December 09, 2007

A good picture will *always* make the blog


Eric took a good shot of his bike, and it reminds me of the conditions here- we had a sort of mini-blizzard last night. Spent 6 hours getting to and from a Nuggets game - that was not even close to worth the time investment. I should have been home drinking hot chocolate and reading a book.

Inexplicably, I typed the wrong number into my frame geometry calculator at some point when doing Eric's frame and made the standover WAY too high, so it's coming back for a toptube removal and replacement. I feel like an idiot, but when you're in the business of making custom stuff, you gotta make sure it's right the first time, and I managed to screw it up. Satisfaction guaranteed, baby! Time to go spend some more money at the powdercoater...

Thursday, December 06, 2007

Style points


I think the recycled rotor disc brace looks better curving backwards. Gonna do 'em all this way, I think, unless someone requests otherwise.

Tuesday, December 04, 2007

A lump of coal, flavored with vanillin

There's nothing more upsetting than getting your hopes up, only to have them dashed in the cruelest possible fashion by harsh reality. Fortunately, my life since approximately junior high has been rife with such experiences. I appreciate their subtleties like fine wines.

As such, I present to you: the world's worst advent calendar.

Now, please note that I'm not particularly religious (and in fact if anything Sarah and I would be more likely to celebrate Hanukah) but advent calendars have several appealing aspects:

1. Mystery. My childhood advent calendar was made of felt and had little pockets (one for each day, duh) which each contained a felt ornament to put onto the felt tree with pins (not so child safe, but whatever) as well as A CANDY SURPRISE. And keep in mind, it was a legitimate surprise. You never knew if you were going to get a caramel turtle or a big disgusting wad of black licorice. In fact, we used to spend a lot of time feeling around in the pockets to try to suss out what was in there. Why we never peeked, or raided them, remains a mystery to me. If I had access to a time machine, I'd give my preadolescent self a few pointers there, that's for sure.

Admittedly, the candy was often covered with felt, or pretty stale by the time we got to it.

2. Counting. Probably less appealing to older kids, but I remember being *really* excited as the numbers got bigger and Christmas approached. For really young kids, it's probably good for teaching patience or something horrible like that. Or possibly making them hate the Romans for inventing the Julian calendar in the first place. Some kind of educational thing, anyway.

3. Tradition. Ours had a star from our great uncle, who was a four star general in some branch of the armed forces, presumably in WWII. I was never totally clear on this. Regardless, the whole thing was made by hand and we participated in repairing it (felt is pretty darn easy to sew, even for kids, since you can use a big dull needle that can only harm you if taken internally) when needed. It was the same every year. Good stuff.

In any case, when a friend gave us a cardboard advent calendar this year, I was pretty psyched, especially since it clearly stated "24 milk chocolate treats" on the front. Let's just say the "PeA" company laid a big fat lump of coal with this one:

1. It's cardboard and plastic. It's probably a pound of waste packaging to contain a big _50 grams_ of "food" (more on that later). Not really surprising, given that the holidays these days are >>>editor's note: long-winded diatribe about holiday consumerism deleted for sake of brevity<<< Bottom line: this is only holiday cheer if you're hoping for a nice full county landfill as a present.

2. The "ornaments" are unbelieveably crappy black and white outline drawings. This is, to be fair, a very cheap item, but still - would it be too much to ask for the colorful part to be on the INSIDE? I mean, honestly, as the holidays approach, this advent calendar looks LESS and LESS festive as it slowly turns into a dull gray blob. Uh, what? I guess you need it to look flashy so the saps will buy it, and it's too expensive to print on both sides of the box. Ho ho ho!

3. This is the real kicker. The "milk chocolate treats" do not, in fact, contain any chocolate. You heard me. No cocoa. Cocoa _butter_, yes. "Chocolate liquor", yes. But no actual cocoa. Ever eat "white chocolate", which is basically just a big wad of fatty goop (cocoa butter) with sugar in it? This is the same stuff, colored brown. At least there's not much of this snotlike substance to choke down, though - each "candy" weighs about 2 grams. Which would be fine if this advent calendar contained, for instance, cocaine, but is pretty insulting in the case of a non-"nose" type candy.