How do you drill a rim for better spoke alignment?

[NeilP]

I have seen worse on here, but no idea how they held up.

Nice to re drill if you have the time to do it and you want it to be 100%, otherwise I'd leave it.
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What height wheel will that be with tyre on? taller than a 26 inch MTB with 2.5 's

I was going to go with 19's, but the tyre width even with the narrowest 19 inch tyres, up at the pedal end of the rear swing arm was too wide to fit in my frame...so I went with 17's

 

[QuestionMan]

The rim is a 19" dirtbike rim and a 2.75 dirtbike tire. I just measured the tire and it is 25" tall.

I will use it in custom wide dropouts so I will have the room. The tire would probably not fit my cross country dropouts, but being 25" tall instead of 27" tall (26" bicycle tire), it may fit because it is shorter.

The 2.75 dirtbike tire compared to a 2.6 26" bicycle tire is just massive and much wider.

 

[NeilP]

Custom swing arm..that explains it. I have a ' Beach cruiser frame' that has wide parallel rear frame but a 19 was too wide for the mtg..so i went 17 and upped the voltage. Well plan to if I can afford it.

134volt or so.maybe up to146-148.

 

[biohazardman]

Like Neil said I have seen worse and I will add plenty of them. If it were me I would drill it also but if you don't want to then just ride it and keep an eye on them. Then drill the rim if you have problems.

 

[johnrobholmes]

Here is a 19" prowheel dirtbike rim with a cromotor laced.

I did not drill holes to align it, the rim had the holes somewhat aligned already.

Do you think I should modify the holes to get a better spoke angle or is it not that bad and I should leave it?

That is not bad enough to cause fast fatigue IMO, but it would make tensioning the wheel a big pain. Most likely the nipples will start to round off before the spoke tension is totally up to snuff, but the wheel could still be built into a decently reliable and true wheel with no modifications.


Instead of drilling the rim, I would redrill the hub flange holes for proper alignment. You wouldn't be able to totally solve the angle with just rim drilling, it would take both countersinking the external hole profile and reshaping the nipple seat. Without some fixturing you won't have an even modification to the wheel, and it will be hard to build true.


I'll try to take some pics of the wheel I am working on at VoltRiders today. It is one of the few cases where rim modification is the best method.


In 99% of the cases, I'm a very firm believer that simple rim drilling never solves the issue at hand. It may alleviate it, but why do a half-fix when the same effort spent drilling new hub flange holes will totally fix it? Even with better hole angles, the nipple seat will still force the nipple into the original direction. On bicycle wheels, a severely angled nipple stuffed through a cross drilled hole only quickens rim failure around the hole. The nipples will still bear down harder on one side and are forced towards a perpendicular seating because of the flat interface.