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No, that's not phonetic
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Discussion Starter · #1 · (Edited)
Here is a study in obsession. :) I have a set of 100 mm rims (aka "hundies") that I will build up at some point this winter. They are heavy. Three and a half pounds apiece, in fact:



To remove some material from the rim, I first decided to get rid of the center inner channel. The rim is a double wall with two vertical stiffeners in the extrusion linking the inner and outer channels.



I needed a guide for my circular saw, so I made to shallow cuts in two blocks of wood:



They fit the rim sidewall hooks, so that the blocks would slide on the rim:



Next I screwed the blocks to my saw, set the depth shallow, and cut the inner center channel next to each vertical stiffener:



I cleaned the cuts up with a flap wheel:





The result was pretty clean and I lost 140g of material in the process:



Next it was on to the drill press and a 1" hole saw. First I went to town on what was left of the center channel:



Then I drilled just the inner wall of the outer channel sections:





The result was shaving 390g off the rim (that's almost a full pound, FYI):



It now basically weighs the same as a Large Marge:



But it offers a bit more float:



Now I just need to clean up the holes a little and put a bit of rim strip over the holes after lacing the wheels up.
 

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Self-defeatist
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Oh HEELLLLLLL YEAH! That is friggin' beautiful. I can't wait to see it built up.
 

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Fatback
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Nice job Phillip

That's about the same method I use, with the exception of a tablesaw instead of a Skilsaw (Ryobi). I like your rim guide jig, you even used VG Fir. Top shelf.
Man, I've eaten lots of alumium over the last few years, so I'm glad it's you and not me.
It's not easy to use a holesaw without a pilot bit.
That is about the maximum mod you can make to that rim-it needs those vertical ribs (and box section) to remain stable. Without those, the rim will invert or crack eventually.
 

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No, that's not phonetic
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Discussion Starter · #5 ·
Schmucker said:
Hopefully you'll adjust your spacing so the holes will be equal distance from the valve hole but otherwise it looks good.
Uh-oh. Busted by the fashion police. :D

Actually, it ended up that way because I put 1.5 holes between adjacent spoke holes. That means that one big rim hole sat next to a drive-side spoke hole (for instance) while the next non-drive-side spoke hole sat between big rims holes. That was the tightest spacing of big holes that would work. Since this is an uneven spacing relative to the spoke holes, it did not end up even at the valve stem or rim seam, though the big holes are still perfectly evenly spaced and balanced across the rim.

I just did the second wheel. I figured I may have gone a little too crazy on drilling the first wheel so on this one I only did ONE big hole between adjacent spoke holes (instead of 1.5 like in the first rim). There is a bit more material bridging the two halves of the rim now, and I think it actually looks a little less Swiss-cheese-like. The weight difference is only 10 grams.

The new wheel is on the right (I will use it in the rear) and the first wheel (I will use on the front) is on the left. You can see the difference in drilling pattern easily:

 

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No, that's not phonetic
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Discussion Starter · #9 ·
EndoRando said:
So these won't go on the initial bike build?
These require 36h hubs, and I think the next batch of hubs don't include any 36's. :sad: They may also spontaneously fold on the first pedal stroke, so I'm not sure I want to commit to these as my main wheelset from the get-go. :)

thirstywork said:
It's not easy to use a holesaw without a pilot bit.
That is about the maximum mod you can make to that rim-it needs those vertical ribs (and box section) to remain stable. Without those, the rim will invert or crack eventually.
The first set of holes I drilled with a pilot bit, but I got a bit annoyed cleaning the resulting scrap out of the bit so I tried it without the pilot (and the scrap just fell out) and with the big beefy drill press the bit never wandered. I had the rim locked down very well too, so that makes a big difference. It would never work hand-drilling.

I am a little concerned about how thin the remaining bridge material between the two rim halves is. The rear rim (the one I drilled with less holes) may be perfectly fine, maybe the front too, but time will tell. Not drilling any holes completely through would probably only add 20g and it would eliminate the need for the rim strip in the center, which will probably add 20g anyway. :rolleyes:
 

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Ologist
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Nice work!!

I don't know anything about engineering and was thinking about doing something like this with my double walled 80s. At what point do they lose integrity? Like you mention you are concerned about the bridge material - if you weighed 50-75 lbs more do you think they would still be strong enough?
 

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Valhalla said:
Nice work!!

I don't know anything about engineering and was thinking about doing something like this with my double walled 80s. At what point do they lose integrity? Like you mention you are concerned about the bridge material - if you weighed 50-75 lbs more do you think they would still be strong enough?
I think you'd be fine doing what he recommended and not removing the center channel center wall and just drilling through it and leaving the inner rim wall intact. It shouldn't change the strength of the rim at all.
 

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No, that's not phonetic
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Discussion Starter · #12 ·
I haven't a clue. The main thing is not to compromise the spoke bed. That is not an issue with the drilling I have done. I have tried to picture what forces are at work, but wheels are mysterious creatures. Once they are built (if they even survive the tensioning process :)), the longevity test will begin. I may not get a chance to lace them up for a while though. I think they will be for snow and sand only though.
 

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Wow, bold move. My first thought was : they will fold in the middle.

Never have drilled or owned a drilled rim it seems the middle could use a little more support, the outer strips are much stronger, weakest link et al.

Put me down for $5 on 'folding in the middle' when you get them built up and tested ;-)
 

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I tried...

...something similar with mixed results...rather, my mechanic tried something similar and I had the mixed results...The rear had the entire inner wall cut out (no remaining box section) with just enough left near the sidewalls for the tire to seat w/o breaking loose at LOW pressures...The hole-saw was not used in the center "bridge" section...The wheel worked great until I was airing a new tire/tube up to 45 psi to fully seat the bead...the concave bridge section "panged" and became convex in a couple of areas, between the holes...It was enough for me to cancel the trip from Aniak to Bethel I had planned for the next day-D'oh!! I kept riding it, though only within easy walking distance of town, for the remainder of the season w/o any problems...it even stayed almost completely true...so maybe not that big a deal?

The front wheel had only the inner wall cut out...to accomodate my 100mm hub / fork we had to move the spoke holes inboard...no problems till a nipple pulled through last month...damnit! Oh well, I guess that's what innovating is all about, trying things till they work...I've got a set from a friend to fall back on for now, though I havn't needed anything but umma's and studs since the first part of December...

-edit-I do not know what the final weight of either hoop was...
 

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No, that's not phonetic
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Discussion Starter · #17 ·
Great beta, damnitman. Much appreciated.

It looks like your holes span (cut across) where the vertical stiffening ribs were, and yet all that went wrong was that sections of the center concavity popped out into a convexities. Not too shabby. I am using the stock spoke holes which are in a thicker rim material area.

The rim I over-drilled will probably pop inside out fairly easily since there is so little (and such thin) material left. The other one, with the fewer holes drilled, should withstand that tendency a bit better I think. I also never go over 20psi to seat the tire, so maybe I will be ok. I will certainly let folks know how I make out.
 

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Self-defeatist
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damnitman said:
...The wheel worked great until I was airing a new tire/tube up to 45 psi to fully seat the bead...the concave bridge section "panged" and became convex in a couple of areas, between the holes...
For some reason...that's so cool. Props to you guys for trying this out. damnitman, I was worried when you mentioned the spoke pulling through, but I see you drilled new spoke holes in the thinner extrusion. I thought about doing that, but now I'm glad I didn't.

I'm a heavy mother** but I think these rims could stand up to some simple mods even under someone my weight.
 
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