Best way to enlarge hubmotor spoke holes? How tight a fit?

Offroader

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I am going to fit 9 gauge spokes to my cromotor. I measured the cromotor holes around 3.3mm in diameter. The 9 gauge spokes are 3.6mm in diameter. I will have to enlarge the holes by .3mm.

I was wondering what is the best way to enlarge these holes? I'm thinking a round file and going slowly?

The other question I have is how tight of a fit should the holes be to the 9 gauge spokes? Should they be as tight a fit as possible or should there be some space?

Thanks
 
Before you do anything have you made sure your rim will accommodate the 9g nipples at the required angle to lace it to a cro motor? because those spokes are not going to flex to accommodate the angle like thinner ones would. And why choose such heavy spokes?
If the plan is all good and you do go with them just drill the flanges, it is only 0.15mm out of each side of the hole.

I would be concerned that 9g spokes are too heavy and will not tension correctly (stretch) this will make a wheel that will suffer loosening spokes and infact not be as strong as one built with the correct gauge spokes for the wheel/bike and its purpose. Might look awesome though! :)
 
I've broke 11/12 gauge many times already, broke 12 gauge. When the 11/12 gauge fail I pop about 5 spokes, when 12 gauge fail I pop 14 spokes.

I'm through with thin spokes. My bike is a 130lbs monster and 11 or 12 gauge don't cut it no matter how properly and evenly tensioned they are.

Maybe if I went easy on the bike they would last, but when you drive hard they won't hold up to the impacts.
 
Yea, OK. I'm not the ES spoke genius - I'd pop over to some of those threads and get more info from the experts on how to prevent the breakage. A better metal, for instance .... http://www.central-wheel.co.uk/spokes/spokes.html for their "SM Pro "Bull Dog" Spokes are made from a high tensile stainless steel developed for the motocross market."
 
Spoke breakage often happens because too large a spoke has been used, these don't stretch or tension properly which causes them to come loose, then the loads are not shared amongst all the spokes causing the one carrying the load to break. Another reason for loosening spokes is a failure of the wheel builder to tension them correctly or "set" the spokes to prevent them coming loose.
A moped weighs more than your "monster" and probably use 13g spokes.

Read this guide;

http://sheldonbrown.com/wheelbuild.html
 
Tench said:
Read this guide; http://sheldonbrown.com/wheelbuild.html
Thanks for that great reference as I'm in the process of contemplating my first wheel build. Made note of reference to http://www.wheelsmith.com/products/#1 as one of the best US spoke makers, who only supply 13, 14 and 15 gauge spokes. What's your recommendation for spokes for hub motor wheels?
 
12 gauge spokes hold up without any issues to most driving and even jumps that I do.

It's when you really whack that rear wheel, like when climbing steps or hitting a large pot hole that they will snap at the elbows. All my spokes break at the elbows, unless they pull out of the nipple and ruin the threads.

I've just ruined a new $100 dollar rim by busting 14 12 gauge spokes after hitting a hole in the park. I'm not messing around with thin spokes anymore. And why should I when I am using a motorcycle rim that can take proper tension on them.
 
Do you have a pic of the broken wheel, i would be interested to see which spokes broke in relation to the damage on the rim caused by the impact. If only to understand a little more myself about the structure of spoked wheels.
 
View the 2nd page of the thread to see 14 spokes that broke. These broke all at the elbow so I removed them to push the bike back home.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=60442&start=25
 
Here is a pic of when I broke what looks like 7 11/12 gauge spokes.

I replaced those and broke another 5 I believe.

Guess what happens to your nice true expensive rim when you break that many spokes in one shot? The rim doesn't have the support of the spokes anymore so bends and you can never true it properly again. I ruined two rims already because of this.

This is why I had enough of spoke breakage and will be going 9/10 gauge. I actually have ordered them already and have them being shipped to me right now.

12 or even 11 gauge spokes are good for bicycles.

12 gauge spokes are not good for a heavy high performance ebike that is made to take hits and abuse.

Funny thing is I used thin 14/15 gauge on the front wheel. I haven't had one problem with them or even had to true them since building that wheel. I think it is speculated that the single cross needed to lace the hub motor just isn't that strong as the 3 cross used for the front wheels. Hub motor wheels kill spokes easily.

 
Offroader said:
Funny thing is I used thin 14/15 gauge on the front wheel. I haven't had one problem with them or even had to true them since building that wheel.

Have you tried a 14g rear wheel build? or did you go heavier straight off the bat.
 
Tench said:
Offroader said:
Funny thing is I used thin 14/15 gauge on the front wheel. I haven't had one problem with them or even had to true them since building that wheel.

Have you tried a 14g rear wheel build? or did you go heavier straight off the bat.

My first build was actually using 13g. That didn't last very long, I broke something like 9 spokes. Tench, the raptor is heavy at 115-130lbs, and since this bike can do a lot of amazing things with its downhill suspension and motorcycle tire, it is very easy to pound that rear wheel and break the spokes.

The problem is the elbows are not strong enough to take hitting curbs that have sharp edges. That is where almost all my spokes have broken. Either climbing stairs or hitting a curb.

When you have a motorcycle tire on the rear you can hit these at pretty hard speeds and not worry about pinch flatting the tire. You could never do this with any bicycle wheel.
 
arkmundi said:
Given that, try a double buttted spoke with 9 gauge at the elbow and tapering to 12 or 13 so its reinforced where it needs to but retains flex. It'd need to be special order. In the process, talk with the manufacturer - maybe they'll suggest a different solution..

Yeah that would work, something like 9/12 gauge. However, here in USA there is really no place that would do that so I am stuck ordering the 9/10 gauge.

I actually was going to recommend Holmes Hobbies get spokes that are 9/12 gauge. The thing is that spoke machines can't cut anything smaller than 12 gauge, so they will not cut 11,10 gauge etc.

Even though 95% of my spokes broke at the elbows, I do get a few spokes that actually pull through the nipple. The threads are ususally broken in the nipple, but I had a recent 12 gauge that actually ruined the threads at the spoke. I never had a spoke break in the middle, it is always the elbow or the threads breaking.

This makes me believe that the threads may need to also be larger to take the forces there so I may be best with a 9/10 gauge. Granted, not all of my spokes came to the top of the nipple, but it is hard to get the right size ordered.

I agree the 9/10 gauge are kind of thick, I do worry about them coming loose. I check spoke at least once per ride, I flip bike around and check for loose spokes. I think the shorter spokes are harder to tension properly as they are not long enough to stretch properly.

The good thing with the 9/10 gauge is that if a spoke does happen to come loose these spokes are so strong that they are a lot less likely to break.
 
I am no spoke expert, and feel a tad hesitant saying anything on the subject but I do believe there is some kind of magic in the right spokes. A wheel I got from BMSbattery kept breaking 12g spokes and untruing, I got sick of it and got my whole wheel re-laced by a local guy (ben more) he said they need to flex. He put 13g spokes in its place, I was a tad hesitant but I have never had a broken spoke on that wheel since or any un-truing and its been like 2 years now.

To me the secret that its not all about spoke thickness lays in the fact that extreme dirt motorbike riders that do 50foot jumps in the air with 9g spokes I think it seems reasonable to use less. Maybe the pattern of the spoke setup needs considering?
What guage do stealth bikes use?
 
Without a doubt we do need to know what works and what doesn't when it comes to heavy hub motors, so do keep us informed on how this wheel build go's, what rim you use, what tyre, tyre pressure etc. We can all stop speculating what might work and what wont when someone has built one that does.
I will certainly be following this so please keep us upto speed.
 
Just got my 9/10 gauge spokes with brass nipples. Compared to the 12 gauge these things are massive, which is what I want because I had no problem cracking the elbows off of the 11/12 gauge.

I had enough of spokes breaking, and it already ruined two of my prowheel rims because of it. Once you pop 5 or more spokes at one time you will bend the rim and it will never be true again.

I am very happy with the quality and the brass nipples fit the prowheel rim perfectly. The one issue that concerns me is I will have to enlarge the holes on my cromotor about .4 mm.

This is a small amount, but the cromotor holes already look pretty close to the edge. I am kind of worried that instead of the spokes breaking the flange will break by the spokes pulling through. I just don't know if this could happen. I ran my finger over the edge of the flange on my old cromotor and I could feel the steal starting to actually push out a little over some holes. :shock:

I wonder if I could weld them stronger? I know I can redrill holes but how do I chamfer the holes on the inside of the hub?

The spokes are 9/10 gauge and the 10 gauge part just about fits through the cromotor hole. If I had to do it again I would order 10 gauge straight spokes, and only because I worry about enlarging the hole any on the cromotor. Although the 9 gauge is such a tiny amount bigger than the 10 gauge, I am kind of happy to have the elbows as strong as I can get them.

I am so happy to have these larger gauge spokes, breaking spokes has been a nightmare for me. I have already broken 5 or more spokes about six times since I got my raptor 1000 miles ago.

While 12 gauge spokes will work, and I've been riding with 12 gauge spokes recently, they will catastrophically fail if you get a reasonably hard hit, like I did landing in a hole in a park when I was trying to be careful. Broke 14 spokes with that hit and warped my new $100 dollar rim. 11/12 gauge spokes are also not strong enough, the 11 gauge elbows will crack with the right hits, however 11/12 gauge spokes I only break about 5 or 6 at a time and not 14. Almost always the hits that crack spokes will be hitting a sharp corner like a curb, stair, or a sharp edge coming up to a paved foot path. You can do 6 foot jumps and that won't break the spokes, go figure.

The other issues I had with the 12 gauge spokes is that sometimes the spoke will pull through the nipple. Depending on the spoke manufacture either the nipple threads was ruined or the spoke threads. These 10 gauge threads are more coarse threaded. I hope these threads are a lot stronger also.

If I happen to crack the elbows off of these 9/10 gauge spokes than I honestly have to give up. These elbows look massive. My recommendation is forget 12 gauge or 11/12 gauge, and order straight 10 gauge with brass nipples that won't rust. They should just fit in the cromotor holes with a little filing.

12 gauge spoke next to 9/10 gauge spoke. The longer nipple are the 10 gauge brass nipples. Smaller nipple is steal.
 
Offroader said:
12 gauge spokes hold up without any issues to most driving and even jumps that I do.

It's when you really whack that rear wheel, like when climbing steps or hitting a large pot hole that they will snap at the elbows. All my spokes break at the elbows, unless they pull out of the nipple and ruin the threads.

I've just ruined a new $100 dollar rim by busting 14 12 gauge spokes after hitting a hole in the park. I'm not messing around with thin spokes anymore. And why should I when I am using a motorcycle rim that can take proper tension on them.


That's the problem. 12 Ga spokes are not THIN spokes. For bike rims, they are horribly fat.

I would bet that the spokes you used weren't of the highest quality. If that was the case, your attempts to 'beef up' your wheel with thicker spokes is like 'the second little Piggy' using fatter sticks of the same wood. Get it thick enough, it might work. But using thinner quality spokes that stretch is akin to being 'the third little Piggy'
 
I don't think my 12 or 11/12 gauge were cheap. They were supposedly sapim ordered from holmes hobbies, although the 12 or 11/12 gauge don't have the name on the spoke.
I believe sapim used to advertise 11/12 gauge ebike spokes but I don't see it on their webpage.

Either way, dirt bikes don't use 12 gauge spokes, and my 130lbs bike which is driven like a dirtbike and also has that hubmotor in the rim and also only able to do 1 cross on the rear, you really shouldn't be messing around with thin spokes.
 
Tench said:
Spoke breakage often happens because too large a spoke has been used

+1
LFP runs quality 14ga spokes on the drive wheel of deathbike after spoke problems with large spokes. This is the one thing I've picked up from Chalo who helped LFP go that direction. For the large spokes you're talking about you must have a motorcycle rim. Plus the cast steel on hubbie spoke flanges is pretty soft, so I'd question moto spokes even with a strong enough rim.
 
Finally built my wheel using 9/10 gauge spokes. Took me like a full day to build and true the wheel/

The holes were not that hard to enlarge. I used 3 drill bits in #26,#27, and #28 to enlarge in 3 steps about .1mm each step. So about .3mm for each hole. Spokes had to be tapped in with a hammer until it cleared the opposite flange because of the tight fit, very stiff spoke, and angle going in to clear opposite flange. Spokes then had to be forcefully bent into place as 9/10 gauge don't bend easily.

This wheel build was by far my best build yet. Perfect uniform tension on each spoke, and the spokes are tightened down very tight or very high tension, close to dirt bike specifications but not as high as I worry about breaking the flange. If these spokes continuously loosen then I will go even tighter / higher tension on the spokes and closer to dirtbike specs.

Wheel was trued to about .01" or .25mm. Spokes were stress relieved multiple times. Hopefully it won't come out of true by much during my first ride.

This is my 5th complete wheel build in about 1200 miles / 4 months of riding with the motorcycle prowheel rims. All previous wheel builds failed multiple times, using 13 gauge, 12 gauge, and 11/12 gauge. Most times I would break about 5 or 6 spokes on a hard hit and I would replace those spokes without removing the tire or doing a complete wheel build. This should hopefully make it understandable why I decided to go with such large spokes.

This is a ridiculously strong wheel I have built here with high quality spokes. Those 9 gauge elbows are just massive, which is important because almost all my spokes broke at the elbows. The other issue I had was spokes that pulled right out of the nipple instead of breaking at the elbow. Depending on the spoke, usually the nipple threads failed and spoke was fine, but I had a 12 gauge that had the spoke threads fail. The threads on these 9/10 should be stronger and hopefully won't pull out of the nipple. I recently had a single 12 gauge spoke pull out of the nipple while doing a stair climb, made a nice pop sound. However, the nipples I used for this build were brass which may not be as strong as the steal nipples I used for my 13,12, and 11/12 build.

If I break these spokes I don't know what the heck I am going to do to build a stronger wheel.

Some issues which should be minor. Because I use an alternating pattern the inner spokes extended past the nipple about 1mm. The outer spokes were mostly about 2-3mm below top of nipple with about two spokes around 4mm below top of nipple. Even though they were 4mm below nipple the spokes still had 3x the diameter of the 10 gauge spoke which I heard is the max that will grab anyway.

The other issue is the spoke doesn't wrap around the flange near the elbow as tightly as the thinner spokes. I'm not sure why this mattered and if it matters in my case.

The obvious place for next breakage will most likely be the flange. I am hoping that because of the sharp spoke angles that some force are distributed sideways in the flange and not completely up, so that the spoke doesn't pull through the thin steal above the spoke hole in the flange.





 
That does look an impressive build, Keep us informed on how it pans out.

I don't know whether you have mentioned it further back in your thread but is this used in a rigid or suspension frame?

A bicycle wheel with its thin spokes has a springiness to it that shares the load and absorbs shocks, this approach is quite clearly a sledge hammer approach to wheel building. It will be very interesting to see how it works out as the heavy hub motors may place the wheel building requirements into a new zone.
 
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