Re-lacing old school Mongoose Pro Class 36 spoke BMX bike rims

One of the many tasks needed to complete on the 1986 Mongoose Expert restoration project was removing and replacing the old rusted spokes from the 20″ 36 hole Pro Class rims. The rims and hubs themselves were in great condition, only needing to be re-greased, however the original spokes and spoke nipples were un-salvageable. Rust had completely set in on every spoke, not just making them ugly as hell but also reducing their strength. A rusted spoke is brittle and can easily snap under pressure, so they needed to go.

1986 Mongoose Expert BMX 7

There were 36 spokes on each rim and as I already had the original spokes, i didn’t need to calculate the spoke length by measuring the hubs and rim ERD’s. To measure the original spoke length I measured from the centre of the spoke flange to the end of the spoke. As the size of the hubs will generally be different on the front and rear wheel, you can expect different lengths. The front spokes on the 20″ Pro Class rims measured 195mm on the front and 194mm on the rear.

On close inspection, the original spokes were tightened right up the the end of the spoke nipple, so longer length spokes were out of the question. Given that there was only 1mm difference between the front and rear spoke length, it would be fine to replace both front and rear with the same shorter spoke length. As the actual spoke length is not critical, although they can’t be too short or too long inside the nipples, 194mm spokes for both front and rear wheels would be fine.

The spoke pattern on the Pro Class rims was slightly different to other wheels I had re-spoked. These were a 36 spoke, straight 4 cross pattern. They also didn’t have the usual interlacing, each spoke ran from the hub flange to the rim, crossing 4 spokes without running under the last spoke. There are many forums and blog that discuss the pro’s and cons of wheel building and the best cross pattern for spoke count. I wasn’t going to get into all that, I wanted to keep this 1986 Mongoose Expert as original as possible, so I decided to lace the rims the same way they came out of the factory.

To add some more colour to the rims and compliment the blue rim strips, I purchased blue anodised nipples instead of silver.

As I hadn’t laced a wheel exactly like this before, i decided to do them one at a time. Keeping one wheel intact with it’s original pattern for reference. I started by completely dismantling the wheel, removing all the old rusted spokes. This was a great opportunity to clean the rims and hubs with steel wool.

Carefully following the lacing process, starting at the valve hole and working clockwise I spoked the entire rim. There are a number of great resources across the web with helpful how-to videos and blogs on lacing, take a look at the links below.

After a few spins tightening and truing the result is fantastic.The addition of the blue anodised nipples looks fantastic and when the rim strips are installed the blue will tie in nicely with the rest of the bike. More images to come.

Wheel building links:

Wheel building with Sheldon Brown

How to build a bicycle wheel – Part 1 36 Spoke (video)

Wheel building masterclass at G Sport

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