Sunday, September 07, 2008

Equipment - (Retro) Zipp

Warning: this is a really, really long post.

I spent a good portion of a prior night disassembling one of my old wheels. It's one of the earlier generation of Zipp wheels, with the first Zipp rear hub that I felt actually worked. I decided to rebuild a front hub with the 440 rim, building myself a more aero front wheel. Since it is to be used in crits, and maybe on the track, I decided to go with a 24 spoke (determined by the rim/hub) two cross build.

The "cross" refers to how many spokes one spoke "crosses" on its way to the rim (spokes anchored in the same side of the hub - so either right side or left side). On a two cross wheel each spoke touches two other spokes before getting to the rim. A three cross wheel's spoke will hit three spokes. Incidentally your maximum number of crosses is approximately your spoke count divided by nine, drop any remainder. 24 divided by 9 is 2 2/3, so 2 cross is your limit. 28 spoke wheels can go to 3x (28/9=3.x), 36 spokes can go to 4x (36/9=4.0), and 48 spoke wheels can go to 5x (48/9=5.x).

Anyway...

The rim, and the rest of the wheel, has seen some interesting things in its life. The wheel was part of my big "aero wheel" shoot out, a night in the mid 90s where I spent a couple hours sprinting on different wheelsets. A very rough test, granted, but I went away with a 7 mph difference between the fastest and slowest wheels - this is the experiment that convinced me that aero wheels were the future.

I should point out that the 440 wheelset came in second out of all my wheels, so that wasn't too bad.

The same rear wheel traveled with me to a number of races, but, unfortunately, I don't remember any significant places or wins. Most of them, I have to admit, took place on the wheel's sister set of 24H Zipp 340s, laced on Campy Nuovo Record (NR) hubs. They were my favorite crit wheels and accelerated like they were shot out of a cannon.

Note: the NR hubs differed from the Super Record (SR) hubs only by the absence of the titanium axles, so from the exterior they were identical. Since titanium technology was primitive "back in the day", most racers opted to skip the expensive and unreliable Ti "upgrades. The most infamous picture of a Super Record bottom bracket is that of Laurent Fignon, sitting on the ground, his bike next to him, his director Cyrille Guimard pleading with him to go on. His bottom bracket axle broke, throwing him to the ground. Despite being in a solo break with many minutes lead in some significant race (Liege Bastogne Liege?), Fignon decided to stop.

The wheel's final race was a doozy - the Pan Am games down somewhere in South America, maybe in 1995, maybe in 1996. A friend of mine, on the national team, borrowed the wheel after I praised its stability, strength, and aero qualities. He used the rear (I recommended using a box section front wheel) and brought back a picture of him in a strung out field, the wheel conspicuous due to its rim height and color. Unfortunately, on the dirt section of the course, he flatted the tire, while in the eventual-winning break.

It has sat, somewhat forgotten, since then.

With my desire to get some more aerodynamic wheels in my repetoire, I had to look at inexpensive options. The least expensive is free, and since I already owned the 440 rim and a matching 24H Campy NR hub, all I needed were spokes.

To keep me company I put my Shooter DVD in the small DVD player in the (new to me) bike room.

The wheel, laced with the heavy bladed spokes, in our old apartment.

I rarely, if ever, used bladed spokes. However, the tall rim (for its day) requires short spokes, and the only ones easily available were bladed spokes meant for 24" front TT wheels.

The process of unlacing the wheel. I was well into the movie by the time I took this picture - Swagger was already on the run.

The blue nipples are sitting in the foreground of the above picture. The "new" NR hub is sitting inside the rim. Other visible things are:
1. The black spoke key (the loop thing near the Zipp label, used to turn the nipple)
2. The spoke nipple driver (silver screwdriver with a bent shaft, used to quickly turn the nipple)
3. The Wheelsmith Spoke Prep in the plastic baggie (little cannisters of what looks like latex paint which keep the spoke nipples from turning too easily - two colors so if you are doing a rear wheel, you can use two different colors to keep the left and right spokes separate).

In order to avoid dropping spoke nipples into the rim (which then relegates the nipple to tumbling about the rim till the end of time), I used an extra spoke (2.0 mm threaded end, just like the original bladed spokes) to extract each spoke nipple.

I'm awkwardly holding the "nipple holding spoke", the spoke wrench, and the very loose "about to fall out" spoke that's actually laced in the wheel. The spoke in my fingers is screwed a couple threads into the spoke nipple. The rest of the spoke nipple is threaded onto the "wheel spoke".

I didn't want to cut the spokes - cutting bladed spokes just seemed wrong. A functional reason? The bladed spokes don't fit through the hole for the spoke nipple.

After a long struggle, the rim was bare.

The rim, albeit with some old glue on it - 475 grams. Since the wheel weighed about 850 grams, the hub, spokes, and nipples were 375 grams.

I debated doing the "lace all the spokes into the hub first" method or the "one quarter of the spokes at a time" method. Because I'm a rote kind of guy, it was getting late, and I wanted to avoid redoing lacing errors, I decided on the more conservative "quarter wheel" method. It's a bit more time consuming but less prone to error.

Swagger, by this time, was exhausted, bloody, and on the run. I wasn't bloody or on the run but my fingers were a bit raw and I was hungry. I went upstairs to have a nice dinner, leaving the movie to play on.

When I came back down, Swagger had gained a new sidekick. Things were getting interesting on the screen. And now I could start building my new super aero crit wheel.

The first thing to do was to start lacing the wheel. Here I'm holding the next nipple in line.

The problem with tall rims with no "secured" eyelets is that spoke nipples can disappear into the abyss between the tire side of the rim and the spoke side of the rim. To install one spoke, I find it best to thread the nipple's top onto a "lacing spoke", stick the nipple through the rim, and catch it by threading it onto the new "wheel spoke".

This is very time consuming.

Insert "lacing spoke" with new nipple on its end.

Once the "wheel spoke" catches threads (with a tug on it to verify), I start turning the spoke nipple so it fully engages the "wheel spoke".

Dropping in the third quarter of spokes. The "head out" spokes make up Quarters One and Two.

My rote wheel build steps are as follows:
1. Find valve hole.
2. Drop spoke in on top side of hub, so the head ends up on the outside.
3. Stick threaded end of spoke in hole next to valve hole. If the holes are staggered (off center, alternating left-right), make sure the spoke is in the correct side.
4. "Install spoke", i.e. thread nipple onto spoke. I leave about 2 threads showing for lacing up a wheel.
5. Skip three holes in the rim, one hole in the hub.
6. Repeat until you end up at first spoke.
This finishes Quarter One because it finishes lacing one quarter of the spokes.

If you end up next to the first spoke on the hub, or anything other than three holes rim-side from the first hole, you made a mistake.

Then flip wheel over, go one more spoke hole away from valve hole. As my wheel building teacher repeated over and over and over, "Always go away from the valve hole!"

Grab a spoke on Quarter Two, i.e. the second quarter of spokes, and drop it into the next spoke hole away from the first spoke of Quarter One. The spoke holes are staggered on the hub, so the holes do not line up when you look at the hub from the side. Repeat all of Quarter One's steps, but on the other side of the hub now.

Quarter Three - then drop spokes in so the elbow is on the outside. Find the third hole from the valve, do whatever crosses you need to do, and proceed.

The first cross spoke - it is crossing TWO heads up spokes (ignore the spokes on the bottom of the hub). The valve hole is below the white square sticker. Note that there are two spokes to its left, one for each side of the hub. The new spoke will sit in the third hole away from the valve hole. This is the start of the Quarter Three of the wheel - you can tell because it's an "elbow out" spoke.

Always go away from the valve hole!

I also always go under the last spoke (and over the others) when crossing spokes, and don't try and cross a spoke from the other side of the hub!

Spokes look very "bowed".

Tension will straighten them out but as the spokes settle, they will lose tension. The wheel will then lose strength. And at some point you'll find yourself on the side of the road with a bunch of loose spokes wondering what just happened. This is not good. The preferred way to deal with bowed spokes (normal in a wheel build) is to bend the spokes into place.

One way to bend the spokes into place is to use your fingers.

See how much you can push down on them?

I find this process extremely satisfying, it's like scratching an itch. I save it as long as I can, so I wait until the wheel is fully laced before I bend the spokes in place. It only takes about 20 seconds so it lasts about as long as scratching an itch.

Using a screwdriver to the same effect. Same 20 seconds. Same itch scratched.

I really torque on the screwdriver. Okay, not really, but it's not a wimpy little tweak either. A good firm push and it's done.

Note how flat the spokes sit on the right side? Note my big fan for trainer riding in the background.

I trued the wheel while Swagger fought his courtroom battle, but the movie had one more section to toss the audience, the closing of the story, resolution for Swagger.

I had to hurry.

The wheel was tensioned, no spoke twist, and I ran upstairs, out to the car, got my pump, came back down, and pumped up the tire in preparation for the glue job. I put on three layers of glue on the rim, one on the tire, not in that order, prepping for the magic moment.

Swagger was busy running around and dodging bullets as I pulled on the tire. A previously mounted tire, it went on smooth as butter. Vittoria CXs are round, straight, relatively durable, and go on smoothly. I spent a miserable 20 to 30 minutes setting up my Conti tubulars and vowed to avoid them as much as possible.

Vittoria CX mounted on the wheel. No glue on my fingers. Incredible.

The final, somewhat perverse check - does the valve point at the logo on the center of the hub?

The one thing I don't like about tubulars is that after you glue them, you can't jump on the bike and go enjoy your newest wheel/tire set up. Instead you have to wait an agonizing 12-24 hours before you can finally enjoy the fruits of your labor.

Maybe that's why tubulars find so much favor among racers. Cognitive dissonance.

Hm.

NOTE: I did NOT detail everything it takes to build a wheel because it would take more time, and I don't want to have someone try to build a wheel on my incomplete instructions. I did want to describe some of the shenanigans necessary to build such a wheel because then everyone who reads this will understand why it costs so much more to build a tall-rim wheel as opposed to a normal one.

3 comments:

Hocam said...

Nice description, I've only built 3 sets of clinchers now but always have trouble getting the valve and logo to match up. Makes me want to just do radial builds...

Any tips?

Aki said...

Lining up the valve hole with the logo takes two things:
1. The first spoke (i.e. the one next to the valve hole)
2. Knowing the cross count for the wheel (2x or whatever). If it is a rear, you are doing two different spoke crosses (radial and 2x for example), and your first spoke is the drive side (I make it so by default), then your cross count is the number of crosses on the same side as your "primary" spoke.

Steps:
A - Insert Primary Spoke, along with the rest of the Quarter One spokes.
B - Figure out which way the hub will twist. By default I twist the hub away from the valve hole.
C - Go the "wrong way" (i.e. towards the valve hole) from the primary spoke. You'll actually just be counting back on the other side of the valve hole.
D - Remember that every other hole in the rim is for the other side of the hub, so those don't count. Only the ones for the Primary Side count.
E - Therefore, from the Primary spoke hole (next to valve hole), you'll pass the valve hole, a hole for the other side, then come to the next spoke hole for your Primary Side. This will be where your "valve hole to hub logo" match up point. Let's call it the Reference Spoke.
F - Figure out where the Reference spoke would sit in the hub. Cross over the right number of spokes (2x for example) and then put the spoke in the appropriate hub hole. The Reference Spoke will now be sort of parallel to the Primary Spoke.
G - Hold the two spokes and line them up with the appropriate holes in the rim. You'll be able to see where the hub logo lines up.
H - If necessary, change your primary spoke until the two spokes you are holding straddle the hub logo.

I - Now you have your Primary Spoke Optimus and Reference Spoke Optimus (i.e. they straddle the hub logo, and the logo is slightly off center so it lines up under the valve hole).

J - Now lace the wheel as normal. Quarter One (including your Primary Spoke Optimus), Quarter Two, Quarter Three (includes Reference Spoke Optimus), and Quarter Four.

I think I'll turn this into a post with picture.

trueno92 said...

hey sprinter, its trueno92 again!

I have moved up from rev-x's to a pair of older cosmic carbones! they are the first gen ones with stainless spokes, 16 spoke front/rear.

I am wondering if you can help me. my rear wheel is hopelessly out of true and its because a couple of the eyelets had broken. Yes, these damn mavic double eyelet nonsense pieces.

You wouldn't have a spare rim OR a busted mavic wheel kicking around?

or more ideally, where to find these eyelets.....?!

safe riding!
andrew