custom wheels: 866g AC Magnesium clinchers, Fred Johnson etc

[ubergoober]

Here is a thread for my own wheels I have built up and ridden in the past few years.

Starting off, the WW forum has to be one of the only places you will see the rare Fred Johnson magnesium rims. They are (were) on Don Becker's incredible Ruegamer and I believe he has tuned some wheels into the 7XXg range. I happened upon a small stash of unfinished blanks that I am building up for myself. I have just these few and they aren't for sale.




and the weight before drilling:


268g for a mildly tuned rim:

[ergott]

Cool I think? The don't look joined.

[ubergoober]

Yep.. on to the tedious part. Where do you cut them so a tire fits just right? The hole spacing took some head scratching before I thought of a jig to do 20/24/28h etc. And the joints need a lot of filing before they fit right and get sleeves and epoxy.

You hold this up to the light and say 'nope, grab the file again'.

[ergott]

You need to measure the rim diameter at the bead seat. You should be as close to 622mm as possible.

http://www.sheldonbrown.com/tire-sizing.html

What if you took some emery paper and folded it and put it in between the joint. Then you are sanding both sides together and they will meet nicely.

[ubergoober]

After overthinking some complicated jigs here's what I came up with:


The hard part was calibrating that length for the perfect tire fit. It worked great once I figured that out.

[ergott]

Are you measuring from the top of the hook or at the bead seat? It's better to measure tire fit at the bead seat.

[ubergoober]

A little more about the FJ mag rims. The history I have heard was that the existing rims were prototypes for a rim company that never happened in the 1990's. He got cold feet from liability issues AFAIK. The name that was to be used was 'Cheetah Paws'.. and I would love to see a logo or sticker if it was ever produced.

If any of this is incorrect I would love to hear more.

When I first saw the cross section it reminded me of the Matrix ISO.

So the next chance I had to compare these to one confirmed the similarity, although with thicker walls due to using a less dense material. Could FJ have modeled his design after these?

[ubergoober]

Are you measuring from the top of the hook or at the bead seat? It's better to measure tire fit at the bead seat.

Both, and neither.
Here with the successful fit I wanted.. no tire lever to install a Conti folding tire:

[ergott]

Are you offset drilling the spoke holes? How are you dealing with that groove in the spoke bed?

Comparing those side to side I see that the left rim has a taller sidewall. On the right, the tire bead should be above that bump so it's at the bottom of the vertical wall. If not the tire isn't seated in the right place.

[HermesSport]

What are they like in the stand?

[ergott]

PS - Alchemy front hub? Nice!

[ubergoober]

Drilling these: yes I have offset all of them so far. And again I had to back off on overthinking these steps. Just for fun here are some Velocity and Mavic rim drilling machines.



My drilling jig is the same as the cutting jig but turned the other way. This technology has 2 settings.
It uses that metal block as a drilling guide.




And the spacing. Apologies if this high tech blows your mind!

[ubergoober]

What are they like in the stand?

The sleeved joints are getting better with practice.

But a pro wheel builder would scoff. But could probably name some production rims that are worse.

[ubergoober]

PS - Alchemy front hub? Nice!

Yep.. big fan. Especially polished.

[xena]

Its not fair ,,,,,I need a set of these. Great thread and congrats on the rims. I'm so envious.
What variations in spokes hubs or are you building them all the same?