Drilling a Stealth 36" rim

[redwelly]

Originally Posted by Dave Cox

how are you shaving down your tires? I spent a while hacking away at a nightrider but it's hard to get the tread thickness consistent.

Hacking is definitely the word for it. I have spent too many hours with a craft knife chopping knobbles off. It wasn't very consistent. But the compound on the Nightrider seems relatively soft, so it smoothed out in a few hundred miles.

I think others have trimmed tyres with hand-held power sanders. That sounds like a good way to go, and much quicker.

Sam

[saskatchewanian]

I haven't seen any 36er lightening projects in a while and was wondering if anyone have ever tried drilling one of the new rims from Coker. You would not be able to use a geared hub but the extra spokes could allow you to get a lighter rim while keeping wheel integrity.

A job for the tax refund when it gets here.

[jtrops]

Originally Posted by saskatchewanian

I haven't seen any 36er lightening projects in a while and was wondering if anyone have ever tried drilling one of the new rims from Coker. You would not be able to use a geared hub but the extra spokes could allow you to get a lighter rim while keeping wheel integrity.

A job for the tax refund when it gets here.

For that matter the Qu-Ax rim. Apparently it's the same rim (per Josh at UDC), so if someone has drilled out one it should be the same for the other.

[Zagira]

Originally Posted by saskatchewanian

I haven't seen any 36er lightening projects in a while and was wondering if anyone have ever tried drilling one of the new rims from Coker. You would not be able to use a geared hub but the extra spokes could allow you to get a lighter rim while keeping wheel integrity.

A job for the tax refund when it gets here.

So has anyone tried this with a 48 hole rim? I have the newest Coker rim, and don't plan on getting a Schlumpf any time soon, and looking to loose weight. I also thought that 48 spokes would be easier to loose weight on the rim.

Does anyone know the weight of the current Coker rim?

[rob.northcott]

You'd have to take a lot out of the rim to make up for the weight of the extra 12 spokes!

TBH, most of the noticeable weight-saving with 36er wheels comes from using a lighter tube (29er or Foss tube in place of the really heavy normal 36er tube) or possibly trimming some rubber from the tyre. Drilling rims has a very poor weight saving vs weakening ratio IMO.

[davidp]

Originally Posted by Zagira

So has anyone tried this with a 48 hole rim? I have the newest Coker rim, and don't plan on getting a Schlumpf any time soon, and looking to loose weight. I also thought that 48 spokes would be easier to loose weight on the rim.

Sask has drilled out his Coker rim and reported the weight savings at ~75g: http://www.unicyclist.com/forums/sho...2&postcount=44

Does anyone know the weight of the current Coker rim?

A year ago I bought a Coker wheel and replaced the hub with a Nimbus 48h ISIS for use in a KH36 frame. When I had everything taken apart I weighed the rim only at 2lbs 9.5oz, which is very close to Sask's 1175g pre-drilled weight.

[Zagira]

Great thanks for the Info!

[Zagira]

Originally Posted by rob.northcott

You'd have to take a lot out of the rim to make up for the weight of the extra 12 spokes!

TBH, most of the noticeable weight-saving with 36er wheels comes from using a lighter tube (29er or Foss tube in place of the really heavy normal 36er tube) or possibly trimming some rubber from the tyre. Drilling rims has a very poor weight saving vs weakening ratio IMO.

Spoke, hub, etc mass still matters less than that on the outside of the circle.
And I was really just asking cause I was curious what people had has results. Just like with these previous examples.

[rob.northcott]

I agree the most important part to save weight from is the outside edge, but I still reckon losing 12 spokes would be more noticeable than 75g from the rim. Not saying it'll make NO difference, just seems like a lot of effort for not a lot of return. I'm sure most drilled rims are made that way just because people think they look cool.

[tveit]

I’m a bit bored at the moment. It’s too much rain outside, wind and cold. I should have been outside riding a lot more. To elevate the enthusiasm to new heights, I have decided to go for a crazy Rim-drill-project.

If a Stealth 36” rim is reduced about 72g with 36 holes of size 7/8”, it should be reduced with about 150g with the “double hole” pattern shown in the figure, if each single hole is drilled as 1”.

I think single holes bigger than 1” might weaken the rim to much concerning the remaining “height” of the rim, seen from the side. On the other hand, the difference here between a single hole and a “double hole” won’t be that big. I’ll go for a “double hole”, testing if that is possible, instead of confirming that a 1” single hole is ok and still wondering if a double could have been an option.

The idea is to keep the inner wall. It’s thin and I won’t save that much by drilling there. And, it will be important that the inner wall is as strong as possible, because it is the main part remaining to keep the stability sideways.

I plan to drill the holes in a brand new Stealth2 rim.

Due to the risk of building a wheel that might collapse, I am planning to put it into low-speed flat-road service, first. That won’t be difficult, concerning the weather outside here nowadays…

(And, yes, I’m very confident that I will manage to build a wheel. The question will be which size of bump makes it crack.)

Cato



Figure showing: a) 1” double-hole, and b) 7/8” single-hole rim drill pattern:

[redwelly]

Good luck, Cato!

Keeping the inside surface will make it easier to deal with for things like rim tape... that becomes a bit of a pain with large holes in a rim. The outer surface is much thicker (about three times I think) so that's where you need to cut out first.

I'm guessing you are experienced with machining and know how to do two overlapping holes without it getting awkward and snagging on the edge of the first when you do the second one? I don't know enough about it to know how to manage that.

Look forward to seeing how it goes

[tveit]

Originally Posted by redwelly

I'm guessing you are experienced with machining and know how to do two overlapping holes without it getting awkward and snagging on the edge of the first when you do the second one?

Well, yes and no. My equipement was obviously not stable enough to do the overlap without a steering pin hole, so I had to first drill two small holes in both the inner and outer surface of the rim. This made it possible to drill (or saw) the overlapping holes, but I still had difficulties to get them exact where they should be due to the drawing. If I should do this over again, I would invest some more time in buiding a better jig.

And, surprisingly much need for sanding the edges afterwards.
After sanding, it looks like all the edges is fine. No cracks.

The weight reduction is about 151g. It feels light, but obviously not that stiff any more..

We will see. I can hardly wait to build the wheel. I'll start now.

[tveit]

The Wheel is now round! With a spoketension of 800 Newton. I had some difficulties with the joint, as the rim was about 1 mm from round at this point, pointing outwards. I'we experienced this with some rims before. The solution had to be a bit higher tension on some of the adjacent spokes. Normally this should not be a problem, but since this rim might be weak, it might do a difference. Do anyone know some trick to flatten a bumpy joint in such a way that all the spokes might have exact the same tension?

The main problem have been to get my new NightRider tyre to clinch. It seem to fit tight to the rim, but with air pressure it have been a pain to get it even. I guess that this do not have anything to do with the fact that the rim is drilled. So, the rim is round, but the tire is not (bumping a millimeter or two at one point). I'll have to do some more work here..

[scotthue]

Awesome!

[Nurse Ben]

You should get one of the new tires, you'll drop at least 300gm from a Nightrider, then use a Foss tube and lose another 150gm over the butly tube.

I was going to suggest tubeless, but that rim ain't looking real stable, so that might not be a good idea.