I’ve drilled the hub-side surface of my Stealth Pro rim with 16mm holes, two between each spoke (apart from at the valve and the seam). This is after previously drilling the tyre-side surface into a pretty doily pattern.
Apparently the answer is no! It was going well until I tried to finish the wheel build and true it up at tension. It was a pain, and just wouldn’t go straight. It was also a little off circular, so I was trying to true that too.
It must have been enough out of round that the tyre (which I had installed nicely with a 29er tube) slowly peeked its bead over the rim. I held it at arm’s length as it went ‘BANG!’, then the tube bulged through the gap… and went BANG a second time. The tube wasn’t punctured so it stayed inflated, squashed out next to the side of the rim.
The ruption must have been enough to upset any equillibrium I had in the spoke tension, and this is the result. Luckily I wasn’t riding at the time.
So unfortunately this drilling pattern can be chalked up to experience.
Wow Sam…that sounds scary. I had it happen to me once (the slow herniation of the tube when the bead pops out, followed by a loud bang!.
I’ve just converted to tubeless. Unfortunately it’s probably as heavy as my original Coker tube because of the amount of sealant the bike shop put in there
Bummer! My TA tyre blew off my Stealth rim the first time I fitted it after swapping from the old steel wheel. I was pumping it up to seat the bead and it exploded at about 40psi. Couldn’t hear for quite some time! Didn’t destroy the rim though - just a tube…
I think Sam’s been using that rim with holes in it (on the inside skin) for a while. The ones on the outside may have killed it - but it could have been just a wheel building cock-up (sorry Sam :p).
I’d guess Tensile’s are probably heavier than those cranks anyway - and I haven’t noticed any Ti Schlumpfs on the market.
Indeed, Rob. The only way to see if this would work was to test it. No-one has shared info on trying this amount of drilling, so no-one had the grounds to state that it was not possible. Our big-wheel parts are overbuilt for road riding, and due to small markets have not been developed as far as bike wheels to see what will work - and what won’t! Similar less extensive drilling has been done by Corbin, Dave Cox et al. with great success.
I see this rim as a sacrifice to progress rather than a waste. Luckily I have another Stealth rim which I will put similar size single holes in, as I know from other people’s that that will work fine.
It may have been possible to build the wheel up without disaster by a more skilled builder… but I think this showed that it would not have taken much stress to kill it, and I wouldn’t like to ride something I wasn’t confident would stay together under me.
You’ll see my rim at unicon, it has 3/4" holes between each spoke hole (except for the rim join and the tube stem hole of course) - I think it’s down around 1025 grams, which really isn’t a huge gain for the effort and slight amount of extra flex, but it sure does look cool.
I think I’ve got 700kms on it or so at this point.
What really needs to become lighter is the tyre. Two kg is a ridiculous amount of rubber. Compare it to a 29"-tyre like the Big Apple which is only half the weight (but still bigger than half the size).
Do you know what spoke tension you ended up with? I wonder if over-tensioning may have been a contributing factor.
Did you ride the rim at all? Or did it self (tension) taco before you even got to ride it?
Chicken:
We will not stop painful rim testing, going too far is the only way of knowing how far we can go. I for one thank Sam for his efforts in advancing rim lightening techniques. I was thinking of doing a similar drilling pattern in the future but my plans have changed somewhat due to this result.
A lighter 36" tire is a great idea though and I plan on building up another ghetto franken-tire when I once again have a big-wheel. (and I will have to if project 32" ever bears fruit)
I haven’t ridden the drilled rim much the last couple of months but up until then there were no problems with it. Speaking to the wheel builder guy who does a lot of uni wheels, he suggested taking it easy on the rim as in he felt the reduced strength while putting the wheel together.
That still sounds like a good saving, and the lightest rim I’ve read about so far (that worked!). Did you drill the inside too, or just the visible surface?
Yes, it is ironic how much the tyres weigh. I have got a Nightrider tyre down to 1610g by shaving it almost bald. But after 1000km of riding it there are now threads showing in some spots, so I won’t ride it apart from for an hour record or something like that. My current tyre of choice is a trimmed TA, at 1850g.
We can’t save an awful lot of weight on rims, but once you are using the lightest available/modded tyre, tube, spokes and nipples then every bit - including modding the rim - helps.
I don’t think the tension was excessive, but it was getting taught. I was at the point where I didn’t want to add tension, so I was loosening spokes to push the rim back into true at each spot rather than tightening the opposing ones.
I rode it very briefly to see how the almost true result felt. It still felt uneven, so I only rode for two minutes. It was during the trueing following that brief ride that the tyre blew off, with a force that caused the whole thing to stress-relieve itself into a taco shape (while I held the frame at arm’s length!).
The rim is drilled through both walls, however I haven’t removed any more metal from the inner wall as you have with your rim. I was actually expecting to lose more weight from it than I did given how much people were saving by drilling out Airfoils, but I think the walls are thinner on the nightrider to begin with. The rim did have significantly more flex after drilling, but it really has been fine through all the road riding (plus the odd curb) I’ve done with it.
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. I know that with 65ish psi in the tire you’re going to spend a long time wearing one down, that’s for sure. definitely would take 5000+kms on pavement.
now to attempt to mount a 29’er tube again, and hope it doesn’t explode off the rim like the last time…
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.
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.
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?
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.
