Monday, April 8, 2013

CX Rear Rim Upgrade

   Last weekend I took my cross bike on an awesome ride.  I went through North Boulder Ranch, took the back roads from Lee Hill to 4 Mile then hit up Betasso.

View counter-clockwise

    I had never ridden such a rough trail on a CX bike, and thought it was a lot of fun... until I got home. I thought my rear rim was just a little out of true from my enthusiastic ride...

1.                               2.                                3.

   If it had been just one place, I would have probably let is slide until it became a larger problem. A wheel will work OK one spoke down. But three! Three spokes were pulled out of the rim. I think that this could have been caused by have an uneven tension on the rim, so these spokes in particular were carrying a lot of weight. That combined with a long ride full of brief but sharp impacts were more than the rim could handle. 
   I hopped on eBay and did a little research into a new wheel, a new wheel set, a new bike, some sunglasses, a vintage Huffy jersey and a team RAD onesie for the little guy. FOCUS. As it turned out, I had this WTB Speed Disc 32 hole rim that a friend gave me. I have never laced up a rim, but though I had nothing to lose here!

Step 1. Tape the old rim to the new rim. What I'm going to do is just move the spokes and nipples one by one to the new rim. Here  I've taped the two rims together. It was important to get the spokes lined up properly, and the valve stem hole in the right spot.

Taped together

Step 2. Move spokes from old rim to new rim. The first thing that I did was loosen all the spokes on the side that the new rim was on. This let all the spokes relax a bit and gave me some wiggle room for the transfer. I started with one spoke, then went about 4 spokes away, and kept going in a somewhat random fashion until I had all the spokes and nipples moved from the old wheel to the new wheel.

Some moved spokes

3. remove old rim, true new wheel. Once all the spokes and nipples were moved from the old rim to the new rim, I untaped the old rim, and took it off. What was left was a very loose lace up of the old hub, spokes and nipples to the new rim.

Almost done

4. Re-True new wheel. Now that the wheel is together, I tightened the spokes to true the wheel. Here it's important to make sure that none of the spokes were over tight or too loose, and the rim i s not too wobbly. This is a bit of guess and check.

   And here is the wheel all built up! The first ride yielded many pops and creaks from the spokes, but that's normal. I took a spoke tool with me for the first ride, since I expected the rim to settle a bit, and wanted to be able to fix any wobbles on the spot.

Final product

   The new rim is 26.5mm wide compared to the 20mm width of the Open Pro that I took off. The wider rim needed to be taken into consideration, because you don't want to run a rim close to or wider than the size of the tire. These tires are 35c, or about 35mm. The wider rim also means a larger contact patch for the back tire. Bad for road, good for trail. Fair trade off. This makes me want to build a whole wheel now!

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