Dirtyginger's Magic Pie wheel rebuild

[DirtyGinge]

Hi All

Just before we get started, just to say that before I offend anyone, Im not stating the below info to be the best way to rebuild my wheel, it was just the way I rebuilt my wheel.....Feel free to add any info chaps..

Wanted to replace my damaged rim, and due to the regular 2000 Watts going through my Magic Pie, decided to go for some of the strongest I could see

Rim...............Mavic double walled EX721 downhill Rim
Spokes..........Sapim Strong 13/14G stainless steel spokes

Now many thanks to Graham at www.tillercycles.co.uk, who cut me 36 custom spoke lengths in one day,for collection the next morning....he can do any length from 100 - 300MM depending on spokes required

now although the pie on 26" wheel has 110 MM spokes, To re-lace to a standard measurement rim that I got, required 119MM spokes ( hence the custom spoke order)

ok, so stage one, remove the old rim

NOW if you are going to re-use your old rim, then don't take each spoke off one by one, but just de-tension them in turn by half turn till they are all loose...them remove.......if you remove them one by one you risk warping the rim..

[DirtyGinge]

So wash everything up nice n clean

Next stage, working on 1 side only, was to re-lace the spokes loosely....make sure that you start at the valve and work away, so that you don't cause any problems with spokes getting in the way of your air pump....

Remember at this stage we aren't tightening spokes, just placing them in the wheel

One trick I got for the first few spokes on double rims, is to insert the spoke in the rim, attach the nipple, pull the nipple through and then hold the nipple with a screwdriver, then remove the spoke, insert into the pie and attach the nipple....this stops the hassle of trying to get nipples in the hole without a magnetic screwdriver....

One side done ?, time to turn over and do the next side

[DirtyGinge]

Now both sides are spoked loosely, its time to bring in the cheap ass truing stand

Now as I want my wheel to be true in my bike, then I use my bike as my truing stand...place the wheel in the frame, tighten all bolts and torque arms as they would be in day to day use, to ensure the wheel is straight as it will be upon completion..

Now for guidance what I use is cable ties on the frame sides...you can have cable ties "Feel" the sides of the rim for side to side alignment, and a cable tie at the outside of the wheel to feel for vertical alignment....

Then I put markings on the cable ties to show me where the centre of the rim should be in relation to the wheel

Now first I try to make each spoke loose to the same thread length, then keep tightening each spoke to half turn until they begin to become tight

[DirtyGinge]

As the spokes become tighter, then you will hear the cable ties begin to rub at the points where the wheel wobbles.......now is time to make the wheel more accurate in its placement

There are several good internet guides on wheel truing once in a "stand" so I'll let you all study those in depth, but I'll just generalise here

http://www.youtube.com/watch?v=jlWXIZaIhgY&feature=related


For vertical truing, where the wheel is high, you tighten both sides of spokes 1/4 turn, and at the opposite side of the wheel, loosen spokes on both sides of the wheel 1/4 turn

For horizontal truing, if you want the rim to move right, the you tighten the right spokes 1.4 turn, and loosen the left spokes 1/4 turn....

How many spokes you adjust will depend on how much of the rim is out of alignment...

PATIENCE IS THE KEY...1/4 turn at a time only.......

Personally, I started with the vertical alignment first, making sure the pie was in the middle of the wheel, then started working on the side to side wobble

Making pen marks on your cable ties can help if you have a lot of adjustment to do

[DirtyGinge]

you can see in the last picture, the cable tie on top checks for vertical wobble and provides some visual guideline....the cable tie on the left will check for side to side wobble once the wheel is centred

[DirtyGinge]

~Once the spokes become tighter, its time for "ping" testing....

I pluck each spoke like a guitar and listen to the sound..... a good tightened spoke should "chime" like a bell as opposed to sounding dull....again adjust the wheel bu 1/4 turn per spoke, check truing, pluck again etc...

it took me about 1 hour after the spokes started to become tight before the wheel was trued...why rush, I had beer

now as this is a rear pie, in order to centre the wheel, spokes on different sides of the wheel are going to make a different note....all the right side should be similar, all the left side should be similar, this is due to the spokes on one side being shorter than the other....

I've found that in the past, trouble with spokes coming loose and broken spokes has been due mostly to all the spokes being too loose, if they are working loose, tighten all spokes up by 1/8 turn and try again...

now after your first mile or 2, check spokes by ping test, after first 10 miles, check again , then check monthly to make sure that one little fella hasnt worked its way loose....

let you know how the maiden voyage goes tomorrow

[GM Canada]

Great stuff Ginge, I love all these projects going on! I need a project!!

Gary

[Webby]

1. Very very nice work Ginge  its a craking idea to upgrade the rim either if you are forced to or just fancy a better spec. And S.Steel spokes ..now that is quality mate!

2. What thickness of spoke did you get? 2mm or 2.5mm I meaured a psoke but can't decide if 2 or 2.5mm as only got a ruler

3. BTW - I got a top tip for you and everyone but forgive me if I am the last person on the planet to know  ; to quickly and neatly get the spoke nut on to new spoke being fitted, I get another spoke and using the thread end, thread it in the other end of the nut (where the screwdriver would go). Lower this through the rim and nicely in line with actual spoke you are fitting.

4. The ever important ping test for tightness ... I figure that for the 700c 'v' the 26" the ping sound is going to be different as the spoke is longer on the 700c. So beware of this all you 700c-ers and do not over tighten. This is how 2 of my spokes snapped last week.

No harm done as all fixed now

.. anyway once again, great work from Ginge - it must be that honey wine I'm sure of it 

[DirtyGinge]

Hi all

yes the ping test........i think probably each wheel will be different.....what I found though is that if you have lots of spokes coming loose on a regular basis, tighten all by half turn, leave for another 20 miles...see if they keep coming loose ....repeat stages...

Hopefully kevin I didnt send you down the wrong path with my 26" wheel sound......where did you find spokes from too ?

HO

[DirtyGinge]

Kevin, will be disturbing your pie peace and quiet soon with some honey wine..life will never be the same....

[Webby]

S*^t - another spoke snapped today .. have asked Graham of tiller for emergancy supply. Will have to be careful until they arrive.

regards the ping sound .. not at all.. actually I rather like all this figure it out yourself, invent yourself and do yourself approach that the ebike world brings you. It kind of part of the fun right?

[Bikemad]

S*^t - another spoke snapped today

Which end of the spoke has broken, is it the threaded end or the bend at the hub end?

I'm guessing it's the bend at the hub flange:

A common reason for spokes to fail on hub motors isn't because the motor puts extra strain on the spokes, or because the spokes aren't a thick enough gauge, it's because of fatigue failure from spokes that aren't held snug against the flange. If the spoke bend radius is too large or too far from the head, then it can flex up and down at the bend with each wheel rotation, eventually causing it to crack and fail.

This problem has been legendary with overseas built hub motors, and we had some Crystalyte shipments where about half the customers would experience spoke breakage on a recurring basis. Ideally the distance between the head and the bend in your spoke will match the thickness of the hub flange, and you won't have problems. But if not, there are two ways to address the situation. One is to insert a washer under the spoke head. The second way is to lace the wheel in an over/under pattern, such that the spoke tension compresses the bend part of the spoke into the flange.

I had to modify my original Magic Pie to enable the tyre to be correctly centred in the frame, and during the rebuild I decided to fit small stainless steel washers to all of my spokes to eliminate the excessive movement and hopefully prevent my spokes from breaking, and I'm very pleased that I have not had any trouble with spokes working loose or breaking since the flange modification was done well over a year ago:



Alan
 

[Webby]

Hi Alan - cricky mate is there anything you don't know! 

Yes it was the elbow / flange end on all 3 counts. I am currently running with one spoke missing until weekend I've got a full set of DT Swiss Champion stainless on there way.

Your advice is very much appreciated and of course will take heed, already thinking that B&Q will be just the place for a bag of washers that size 

I am also going to put a dab of loctite meduim strength on the thread to help them from working loose and lessen the temptation of me to over stress them.

I notice from your picture that flange position alternates from facing in and then facing out - is ther a set pattern for that? To be honest I did not ntice this when I replaced 2 the other day and just assumed that the end of the spoke flange end face away from the wheel instead of some of them facing though and across the other side (if that make sense?)

Cheers
Webby

[_GonZo_]

Do not use Loctite on the threads use the proper staff that is thread lock normal or medium.
With loctite you can have big problems when trying to loosen them and when installing them because it cures too fast.

[Bikemad]

already thinking that B&Q will be just the place for a bag of washers that size 

I notice from your picture that flange position alternates from facing in and then facing out - is ther a set pattern for that? To be honest I did not notice this when I replaced 2 the other day and just assumed that the end of the spoke flange end face away from the wheel instead of some of them facing though and across the other side (if that make sense?)

Webby, I'm not sure if B&Q will stock stainless steel washers in that size, I found mine in a local building supplies and tools shop who keep a pretty good range of nuts, bolts & fasteners etc.

My spokes alternate because I have the early MkI Pie with cross over spokes (which unfortunately produces an excessive spoke/rim angle and curved spokes due to the large hub diameter - see attachment below). On the later MkII Pie's, like yours, the spokes all exit from on the inside of the flange and have the heads visible on the outside.

For anyone using a spoked Magic Pie on a trike, it would be more able to withstand the greater lateral forces encountered when cornering if the heads were on the inside and the spokes wrapped around the outside of the flange, but I guess the spokes might need to be slightly longer to allow for that.

Alan