Carbon rims and radial trueness

Lateral trueness is easy; radial trueness is hard. I'm always looking for better tools, and this morning I was researching Morningstar tools. They offer a dial-based truing gauge that will fit to a Park TS-2. Slowtwitch was the first review that popped up. Buried within an article on wheel building is a point about the difference between carbon and aluminum rims:

This is also the point where carbon and aluminum wheels differ. Carbon rims are much stiffer than aluminum. Put simply, the amount that you can radially manipulate a carbon rim is MUCH less than aluminum. As such, when adjusting radial trueness, you need to adjust many more spokes. Think of it as shifting the entire rim up or down – rather than bending a part of that rim to be more straight. Instead of adjusting 4 spokes, I might adjust 8 or 10. This also brings up the point that carbon wheels rely much more on roundness of the rim itself for a straight wheel; an imperfect rim cannot be manipulated very much (unlike aluminum). 

This is why cheap carbon rims are a really bad idea. There are plenty of other reasons why cheap carbon is a bad idea--labor conditions in those Chinese factories, for starters. Next up would be a total lack of warranty coverage for manufacturing defects.

Want a legit rim and customer service? See Brandon at the Bike Hub Store. Always great service and they're the only consumer source of Gigantex rims that I've found:

http://www.bikehubstore.com/category-s/124.htm

Getting back on that horse

It is almost July, and that means cross season is almost upon us. That means taking a break from riding all the wheels I've been building, and returning to the truing stand. What have I been riding? On the road bike, a lovely Pacenti SL23 wheelset with a 20 hole White Industries H2 on the front, and a 24 hole Powertap SL (with G3 internals) on the rear. These are shod with 700 x 25 mm Contis. Life below 90 psi is splendid.

Ongoing impressions of the Pacenti:

• They work very well with standard size road brake pads, exhibiting none of the pulsing I was experiencing with V-brakes. I suspect this has something to do with the length of the pad.
• Mounting tires is a real challenge. I suspect this is because of the tubeless rim design. Once I get a frame with the proper clearance, these will be an excellent candidate for the 28 mm Hutchinsons.
• My initial concern about the low spoke count was unfounded. These rims are plenty stiff for someone who goes 175.

What I am working on today:

• Relacing a rear 24 hole White Industries T-11 (Campy) onto a 50 mm Yishun carbon tubular. This will be straight gauge spokes in 2x (drive), 0x (non drive) pattern. This will be my rear wheel for cross.
• Relacing a rear 24 hole White Industries T-11 (Shimano) onto a 50 mm Yishun carbon tubular. This will be the same pattern as the above wheel. 
• Lacing a front 20 hole White Industries T-11 onto a 50 mm Yishun carbon tubular. This will be 0x with straight gauge spokes. This will be my front wheel for cross.

I'll go into the relacing in a separate post.

Here's the assembly line for today:

• T-11 hub--titanium cassette body--no gouging, unlike Chris King.
• 12mm brass nipples drying out after soaking overnight in triflow. Lube those nipples when building with carbon!
• Spokes and the all important spoke ruler.
• Lastly, my trusty and calibrated Park Tool TS-2 stand.

Updates to follow!

Mickie's Front Wheel

Currently building up a set for my friend Mickie. This will be her do-everything wheelset. Criteria: light, durable, comfortable and pretty. We chose navy blue Chris King R45 hubs in 24 and 28 drillings, with 2x Sapim Race spokes, 12mm brass nipples, and Pacenti SL23 rims.

The set is half way complete. This morning I finished the front, which I find more challenging than the rear.

The workspace: stand, Spotify, coffee mug, and spoke ruler. The pieces of tape on the stand are used to mark the rim in quarter sections, which aids in spoke tensioning.

One of the best.

Vital equipment: spoke tensiometer, spoke wrench, and tension chart. Wheel building is like a basketball game: the final minutes of the game can occupy a third of your time. This wheel didn't foul. Thankfully.

Pacenti rear Dura Ace 9000 wheel is done!

I managed to stretch this project out over 10 days. Test ride this afternoon. This wheel goes on my better half's pit bike. The DA hub is nice, but for the money, White Industries and Chris Kings are better. The verdict is still out on the rim. I've been riding the front Pacenti/DA wheel for 3 weeks. There was some initial pulsing when braking, but that seems to be going away.

The weight of the set should be around 1500 grams. Not bad for about $600 invested.

I can build wheels cheaper and lighter, but not better. These hubs should last 5 years of racing or 10 years of riding.

Ride report to follow....

Pacenti SL23 first impressions

Updated August 18

My new Dura Ace 9000 hubs arrived last week after what seemed like an eternity. The hubs, which are in 24/28 hole drilling, are pleasing to look at and are respectably light. Like anything with the Dura Ace name they'll last forever. The 7800 hubs Mateo raced on for three season still had intact grease and seals. Wizardry.

What the Dura Ace hubs are not is a good value. At the moment they are priced similarly to Chris King R45s and way out front of White Industries. Those are all equally good options, and will all be in service 5-10 years from now.

For this build I used the Pacenti SL23 rim. This was my first build on the rim and my impression is very good. The height of the brake track appears to be fairly generous. The rim is slightly taller and rounder than the comparable HED Belgium C2. The finish is flawless. And there were no metal burrs remaining in the rim from production. Most importantly: the rim is approximately 1mm wider than the HED, Velocity A23, or the H Plus Son Archetype. Added bonus: it is lighter than all those other options.

So how does it ride? Very nicely. The rim has a pleasing lateral stiffness, especially when combined with the 2x lacing.

Only potential downside: when I was truing the wheel I watched the stand's feeler gauge take off a sliver of metal from the brake track. Not sure if this happens with other rims, or whether this is a softer alloy. Kinda freaked me out.

Update: this is a great rim and unless the HED Belgian Plus (~$150 and non existent) knocks my socks off, this rim ($98 and available everywhere in multiple drillings) will be my go-to for future builds.

• The brake pulsing I experienced seems to happen only with long v-brake cartridges. Braking with standard road pads is smooth.
• There's no problem with pitting on the braking surface. I examined my pads after 500 miles of racing and city riding and there's no more embedded metal than one would expect. In fact, there was almost none.
• The only caution when building on these rims seems to be a tendency for the nipples to bind/stick during tensioning. These require more spoke alignment and stress relief than other rims. Again, I recommend these rims without reservation. They're the best combination of weight, value, and quality.

Spring Cleaning

I have always found that the best time to clean is when there's something else you should be doing, but don't want to. Like income tax returns. Compared to doing those, cleaning out the stash of bike parts is a joy.

I needed to dispose of two aluminum rims and a carbon fork. This task was made less desirable by the fact that I didn't simply want to leave these items on the curb--they were structurally unsound--so modifications were required.

The first to fall victim to the hacksaw blade was a 2006 Cannondale Premium+ full carbon fork. This fork was top-of-the-line back in its day, even featuring carbon dropouts. It was and still is ridiculously light. The problem is it was mounted to a bike that hit the back end of a Buick at 20 mph. Carbon is tough, but carbon also cracks. I didn't want some hipster douche salvaging this fork so I sawed it at the crown.

Wow. New respect for Cannondale carbon forks!

By comparison, here's the top of the steerer tube.

Next to fall victim to the hacksaw: a DT Swiss RR 1.1 rim. This rim is the Swiss interpretation of the venerable Mavic Open Pro rim. I believe the Swiss version is lighter and cheaper. Anyway, the rim in question was part of the rear wheel on my track bike. I just rebuilt the wheel when it took a 2" roofing nail in the tire. The nail punctured the rim bridge and then exited the rim's sidewall. The damage was impressive. I also rode it for another 12 months before replacing it with an H Plus Son Archetype.

Here's the DT Swiss next to a HED Ardennes rim.

The final victim was the most painful for me: a 24 hole HED Ardennes Scandium rim. HED rims are sold to the public under the name Belgian. These are regular 6000 series aluminum. HED saves the good and expensive stuff for their pre-built wheels. This rim was a Scandium version, which like the Higgs-Boson particle and unicorns, was just too good to be true. And it was, because I ended up destroying the rim during wheel building. Lesson: Scandium is lighter than 6000 series aluminum, but not necessarily as strong.

I cut apart both rims and here's the result.

The HED (left) is significantly wider. The DT Swiss rim (right) is significantly overbuilt.

Coming up: Pancetti SL23 rims laced to Dura Ace 9000 24/28 hole hubs. Hotness!

Carbon Toe-in

If I'm going to Hell, my punishment will be listening to improperly maintained, noisy bikes for eternity. Breaking in this carbon wheelset was a scared-straight visit to Hell: no matter what I did, I couldn't silence the squealing brakes. I sanded the brake pads (they build up a glaze), I meticulously cleaned the brake track with alcohol and acetone, and I even tried riding the brakes thinking it was only a matter of breaking-in the new rim's brake track. Nothing. The brakes were screeching loud enough to make neighborhood dogs howl. I concluded: this is the difference between a $200 Chinese carbon rim and a $800 Enve or Zipp rim.

As I was about to throw down some mad cash on different brake pads--a last attempt before writing off the wheelset--I researched the squealing carbon rim problem. There are three prevailing opinions: 1) it's a problem with cheaper rims; 2) it's  problem with certain rim/pad combinations; and 3) it's a problem related to improper pad toe-in. I had assumed #1 and #2, but hadn't considered #3.

So I toed in my yellow Swiss Stop pads on my road bike. Now my braking is quiet.

Who knew? From cross racing I was familiar with the cursed cantilever tendencies to howl unless toed-in. I never thought the same technique would work for a road bike with carbon rims. Lesson learned.

Only the finest brake pads that 60 bucks can buy.

That's some aggressive toe-in, son.