Friday, October 15, 2010

Wheel Problems - Again

I bought the last Ultegra 6700 - Mavic OpenPro rear wheel Performance Bike Shop had in their warehouse yesterday for a simple reason - I need to send my custom built rear wheel back to Colorado Cyclist for a warranty inspection. It's showing signs of failure at the SUP weld joint, and I have no clue why. None of this stuff is made in heaven, so mfg defects do happen. Mavic is reportedly very good about standing behind their stuff, so I'm hopeful this turns out well.

There's an extra piece of aluminum laid on the inside of the rim, about the size of a wire bread-wrapper tie, for shoring up the weld area. You can see its "shadow" pretty well through the machined, once-smooth braking surface, in the bottom picture.

My hunch is the post-weld rim was bulging out, so the machining to make the braking surface smooth again cut away too much material, making the rim wall too thin. With 32 spokes pulling with 30 lbs of force, there's almost a half-ton of pressure trying to crush the rim - mashing the ends together at the weld.

The danger, aside from outright wheel failure, is the brake grabs at the point of the weld. This will tend to lock the rear wheel on a descent, resulting in a sideways-skid, and causing you to lose control. 

On paper my 2 rear wheels will be almost identical, but I have heard the Performance wheel uses cheap spokes and nipples, and ships out of true. Good to have a neighbor with a pro wheel-truing setup who owes you favors! As long as it can stand in when I need a spare it's done its job.

If Colorado Cyclists does rebuild the wheel, especially on warranty, I am going to ask them to use DT 14/15 double butted spokes on the drive side. I love my DT Revolution 14/17 super-butted spokes, but they are a bit too flexy on the drive side at my weight and power, and I don't like asymmetrical flexing out back.

I also realized that any serious commitment to training, especially a 2X Century, requires enough spare gear to stick to a training program - and a spare set of wheels is #1 on any such list. As it was I got a killer deal on the Performance wheel, and didn't have to pay shipping as they shipped it to a local store. (tip: if a company has a physical store in your state they are required to collect state sales tax, BUT, they will almost always ship to that store for free if you ask, and most advertise they will do just that. The cost of shipping and tax are usually the same)

I need a new seat, and maybe seatpost too, as my seat just doesn't work for the TT position, and is too old and spongy to make a good 2x Century saddle. I will ride the seat the rest of the winter and keep an eye out for a deal on the Specialized Romin (the spelling has Caesar rolling in his grave, I'm sure), as spongy has a way of getting nice and hard in the cold of winter.

The linked review is pretty thorough, with lots of price and weight info, but I do wish every last reviewer would stop insisting that "The Romin has a cut-out section that runs the length of the saddle..." Clearly, from the picture, anyone can see it does NOT!

I had to make a trip to REI to exchange a pair of Novara Road Gel shorts (the best warm-weather chamois on earth) for a new pair, as the stitching that holds the chamois to the short was coming loose. It's times like these you really love that NQA return policy at REI! While there I looked at the new Shimano 6700 compact crank.

The entire area between the 34T and 50T is covered by a smooth piece of black, ABS plastic, so the chain has nowhere to go but between the gears. Sweet! I am very concerned though about those very, very thin teeth wearing well. The replacement cost of the outer ring is a whopping $277 street! OMFG! Not gear for 2X Century training rides - unless they start using ceramic coatings, as Middleburn has done.

A call has gone out for 2X Century training partners at our bike club. I am going to suggest regular face-2-face get-togethers, maybe with slide shows and such, because there are just so many questions to be answered.


Gotta Run..Gotta Ride said...

You are so lucky to have all of the knowledge that you have to know exactly what you need! Good thing you found that in the wheel before your brakes did lock up and place you on the road flat out!

I am also in the market for a new seat. LONG-OVERDUE.

Grey Beard said...

I think the Romin saddle makes use of a very obvious fact, the nose of most saddles is FAR narrower than the area it interfaces with - at least for guys.

By providing a much wider, flatter nose I am hopeful my soreness and numbing will go away, and I will feel more connected to the bike.