Lacing 28 hole rim to 36 hole hub. another skill learned

NeilP

NeilP

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Nov 27, 2010
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49.17303, -2.05354 Jersey, Europe
I am trying to find a way to fit a tyre to a small hub motor to make a scooter type folding transport

Am looking at either a solid tyre direct on the hub or a 12 or 16 inch rim

Just acquired some kids bikes with small wheels, but until now I totally forgot about the different number of spoke holes in the rim

I have a 36 hole hub, and two rims
One 28 hole and one has 20

Any suggestions apart from re drilling. Will be starting with over lengthy spokes and cutting to suit.

Plywood disks maybe,..., bolted together either side ???
 
If you don't need the full strength of the greater number of spokes, just leave some hub holes empty. If the numbers are divisible evenly, you can leave every Nth hole empty. Trueing up the rim is harder to do this way, as the spokes won't pull evenly, so you need to start with as straight a rim as possible, and as even a tension on the spokes as possible. If you bend the rim later like on a pothole, you might have to replace the rim rather than just retrue it, since you might not be able to retrue it right if the bend is in the wrong place.

18 holes on each hub flange.

10 holes on each rim side for 20 hole

14 holes on each rim side for 28.


10/18 = 5/9 so four of each 9 will be empty, you can almost simply skip every other one; at some point you'll have two spokes in a row.

14/18 = 7/9 so 2 of each 9 empty, you'd have four in a row, a gap, five in a row, a gap, etc.
 
Maybe I will have to look at it again, but on the rough drawings I did I could not come up with a pattern that gave a spacing with a equal gap. Because the pattern is circular/ repeating, it ever works out with the numbers I have

Am tempted to use a couple of blocks of wood, cut to fit over the hub, with the rim like a band holding it al together, rather like an old cart wheel
 
http://sheldonbrown.com/mismatch/

I knew there was an article I'd read about it, but I had to google to find it. Oddly enough, I googled using a quote of your thread title, and it is the VERY FIRST hit! :lol:
 
Amazing how Google works sometime
I had seen same article previously, but been unable to recal where, and google on the iPhone gave bugger all help, so I tried a post here
Cheers for link
 
Anyone care to do some trig for me and re calculate those figures for a 20 hole rim?

I am sure I could probably get my head around it..but looking for an easy solution..like someone else do it for me :wink:
 
Well had a play this afternoon. and think I will have to either stick a large punch in the rim spoke holes and deform the holes to create angled seats for the nipples, or come up with my own spoke arrangement.

This was done with the spokes I had around..so all far too long, but it give the idea.

ERD = 292mm
Hub spoke diameter = 163mm
Hub 36 holes
Rim 24 holes

24 36 spoke 16 inch rim.jpg
 
Going to have to be a radial pattern, think i have worked it out. Been on this for hours now, should have just done a spreadsheet, but no, did it all long hand

Hub in drawing is not to scale

IMG_0002.jpg
 
That solution is cool-- and because the spokes are not truly radial, you won't have the usual radial lacing issue regarding spoke windup.

Just for a point of comparison, here's what I came up with for a shop owner friend of mine in Seattle who was facing a similar problem:
http://www.rideyourbike.com/36hub24rim.shtml

That was a while ago, and if I were to try it today, I'd attempt to get all the cross equivalent values down to 1 or less, to improve insertion angle.

Chalo
 
Praise indeed, thanks very much.

That motor came form a granny e-bike, ( A Thompson Euro Tourer)
Fittted as standard with a 24 inch wheel, I got it up to 30mph at 100 volts and about 40 amps. So not a fast wind motor.

That is a 16 inch wheel from kids bike. I want to try fitting it in a home made Go-ped style scooter. Very basic. big section of alloy box section, for the batteries, couple of arms out the back for wheel support and some sort of steering at the front. and Xlyte 7240 controller. probably at 100 volts again. :twisted:
 
Well i did it.
Did the calculations, cut the spokes and fitted it all up this afternoon. Not trued it yet, and may yet need to trim a little of some of the spokes...only truing will tell.

One slight cock up. I was aware of the issue, thought about it, knew what i was going to do, then noticed the rim holes were fractionally offset for left/right side spokes...so laced for that forgetting the issue of the tyre valve.
So all spokes out tomorrow to rotate the rim 6 holes around.

IMG_0128.jpg

Oh bugger.
IMG_0129.jpg

IMG_0130.jpg
fitted up to the scooter for trueing.

Am going to need to re make the mounting bars to drop the height of the platform and add torque plates
 
It is a shame to have to respoke for that f******g tire valve but I have been there and done that too. Some RV places sell 90 degree valve stems that can help! We have to use those on 20" 9C hub motor wheels no matter how the spokes are done.
otherDoc
 
Well it is not even tightened up or trued yet.

I only started assembling it because it was the easiest way to keep the spokes in order as I cut them. 4 different lengths.

I had planned to strip it down again any how to clean up the rim better, (rusty chrome) and attend to any over long spokes, so not a big issue
 
Well I mounted in up in the scooter today. still need to do the electrics and and rear mounting box for the controller and wiring.

file.php


http://www.endless-sphere.com/forums/viewtopic.php?f=35&t=39798&p=581810#p581810
 
Wow Neil! That is some neat metalwork for the rear mount/torque arm. Nice!
otherDoc
 
Drilled the clamps slightly off true by about 5 degrees, so had to enlarge the holes in the top clamps a bit
They are aluminium , so not sure how well they will hold up.
I used heli-coil inserts in the lower blocks, If they do pull, then I will drill all the way and cut slots to take SS nuts underside.

I do not have access to mill or laser or water cutting, so it is all hand worked. laborious, but no other way
 
Good hand filing and cutting is worth it's weight in gold. Look at Aussie Jester's bikes! It is an art form! Nice work!
otherDoc
 
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