GoldenMotor.com Forum
General Category => General Discussions => Topic started by: DirtyGinge on May 01, 2011, 09:39:47 PM
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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..
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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
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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
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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
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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
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~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 :P
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 :D
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Great stuff Ginge, I love all these projects going on! I need a project!!
Gary
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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 :D :D
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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
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Kevin, will be disturbing your pie peace and quiet soon with some honey wine..life will never be the same....
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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?
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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:
(http://www.arhservices.co.uk/GoldenMotor/Spokewashers.JPG)
Alan
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Hi Alan - cricky mate is there anything you don't know! ;D
Yes it was the elbow / flange end on all 3 counts. I am currently running with one spoke missing until weekend :P 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
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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.
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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
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Thanks Alan - that explains it. Re. washers - In Camberley near me on the London road there is a great engineers paradise - AHC - and thats going to be the place to go me thinks.
_Gonzo_ - re: loctite .. I hear you and actually if you google around, alot of folks say the same thing as you ... BUT ... being the rebel I am on the very rare occasion (sorry its not my fault but its to do with my Myers Briggs profile) I had one rouge spoke in the early days - I know because I marked the bugger with tape and it was the same one that kept coming loose - since I dabbed loctite meduim on it, it has been sound ..and very stable and I am approaching nearly 1000 miles now on that pie!
The freindly chaps at AHC said that Loctite medium is designed to be 'undone' with hand tools and that's exactly what it does. Its not a 'solid' glue but rather a sort of sticky thing. Having said that, have you experienced problems first hand?
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Thanks for your great info!
But how did you measure the correct spokes lenght?
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There are several spoke calculators around that will help you. However I have always found graham@tillercyles great help in both calculating the lengths accurately, and then supplying top quality custom lengths ...
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Okay thanks for your reply!
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What is the ERD of the 26" GM rim?
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OK, folks, to me an "ERD" is the acronym for "Entity Relationship Diagram", which is a description of a database. What are you referring to with "ERD"?
Make me smarter, please. I need all the help I can get.:)
TTFN,
Dennis
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Entity Relationship Diagram = Nak!
Evil Rubber Ducky = Ack!
:)
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Hahaha almost good! ;D
Effective rim diameter ;D
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OK, folks, to me an "ERD" is the acronym for "Entity Relationship Diagram", which is a description of a database. What are you referring to with "ERD"?
Make me smarter, please. I need all the help I can get.:)
(http://www.arhservices.co.uk/GoldenMotor/emoticons/everyday_think_230608.GIF)
Since you asked so nicely;
ERD Entity Relationship Diagram
ERD Ethical and Religious Directives (Catholic Health Care Services)
ERD Emergency Repair Disk
ERD Episcopal Relief and Development
ERD Economic Relations Division (Bangladesh)
ERD Event-Related Desynchronization
ERD Extended Reach Drilling (oil industry)
ERD Emergency Response Division
ERD Elastic Recoil Detection
ERD Environmental Restoration Division
ERD Energy Recovery Device
ERD Explosives Regulatory Division
ERD Eligible Rollover Distribution
ERD Early Return of Dependents
ERD effective rim diameter (cycles)
ERD Ecosystems Research Division (US EPA)
ERD Employee Relations Division
ERD Esophageal Reflux Disease
ERD Earthquake Resistant Design
ERD Early Random Drop
ERD Expected Reinsurer Deficit (CAS Risk Transfer Metric)
eRD E-Referencedesk
ERD Estimated Release Date
ERD Early Release Date (prision)
ERD Emergency Reserve Decoration (UK)
ERD Environmental Radiation Data
ERD Early Renal Damage
ERD Electronic Restraint Device
ERD Equal-Cost-Route Descriptor (Cisco)
ERD Equivalent Residual Dose
ERD Enterprise Relational Database
ERD Equipment Readiness Date
ERD Experimental Research Design
ERD Employment Relations Divisions (Montana)
ERD External Reuse Density
ERD External Requirements Document
ERD Estimating Requirements Document (mini Cost Analysis Requirements Document)
ERD Engineering Review Diagram
Erd Total Residential Energy Demand (Carolina Environmental Program)
ERD Expected Recovery Date (medical terminology)
ERD Envelope Recipient Domain (email)
ERD Exchange Rate Difference (finance)
ERD Électricité de France Réseaux de Distribution (French)
ERD External Relations Department (various organizations)
It could also be used to describe the typical British weather that I've had to put up with this "Summer" - Enormous Rain Drops!
Visual proof attached below (taken on 5th August!!).
Anyway, this should help to clarify the intended meaning:
Effective Rim Diameter.
This is the rim diameter measured at the nipple seats in the spoke holes, plus the thickness of the two nipple heads.
The E.R.D. is needed for calculating the correct spoke length.
I tried to determine the ERD on a built up wheel and I reckon it is somewhere around 518mm on the 26" GM rim that I measured.
(The inside diameter is approximately 508mm and the 13mm long nipples only have ~8mm protruding from the inside of the rim.)
The factory fitted spokes are 110mm long when measured from the inside of the elbow:
(http://www.arhservices.co.uk/GoldenMotor/MPIIspoke.JPG)
Alan
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Hi Alan,
Ok, I give up! I now want to remain dumb as a post! Evil Rubber Ducky it is.
I can't imagine how much work went into compiling your list. Elastic Recoil Detection! That sounds like porno! Thanks for the laugh.
TTFN,
Dennis
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Hahah thanks!
Does anyone knows where I can download MP III motor drawing pdf?
Or the anyone knowns the dimenions of the MP3 motor?
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http://www.goldenmotor.com/hubmotors/Magic%20Pie%20Sizes%20Model.pdf (http://www.goldenmotor.com/hubmotors/Magic%20Pie%20Sizes%20Model.pdf)
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Thanks mate!
So the diameter is 203,5mm?
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I gather you don't know how to read a mechanical dimensions type drawing.
The width of the axle is 203.5mm. It looks to me like the diameter is 299mm (11.77"). Perhaps Alan can confirm that. He doesn't have anything to do except mope around in the rain anyway.
;)
Jeff
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Aaha yes I see it now you are correct!
Because it says for 135mm rear fork :-*
Thanks!
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I tried several spokes calculators.
But the MP3 hub dimensions are very different compare to a nomal MTB rim.
How did the topic starter ever calculate the spokes length.
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It looks to me like the diameter is 299mm (11.77"). Perhaps Alan can confirm that. He doesn't have anything to do except mope around in the rain anyway.
The drawing you have read the measurements from is for the earlier Magic Pies. Although the spacing is different, the PCD (Pitch Circle Diameter) of the spoke holes should still be the same for the MPIII.
I tried to accurately measure my Original Magic Pie when I had to design and fabricate a flange ring modification (http://goldenmotor.com/SMF/index.php?topic=1653.msg9193#msg9193), and according to my CAD files, I've used a measurement of 297.6mm for the spoke hole PCD, but it's quite possible that the 299mm shown on the pdf drawing is the correct measurement.
I tried several spokes calculators.
But the MP III hub dimensions are very different compare to a nomal MTB rim.
But even with an exact measurement, the typical spoke length calculator programs are not likely to calculate the correct spoke length accurately for the MPIII because of its unconventional spacing of the spoke holes around the hub flanges:
(http://goldenmotor.com/SMF/index.php?action=dlattach;topic=1653.0;attach=1741;image) (http://goldenmotor.com/SMF/index.php?action=dlattach;topic=1653.0;attach=1741;image)
Alan
P.S. I haven't been moping around in the rain, I've just spent the weekend driving ~900 miles (up to Scotland and back) to visit my granddaughter for her 2nd birthday, and it rained during most of the journey back home. >:(
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Thanks a lot!
So I think it's just trial and error methode to find out the right spokes length?
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I have bought some spare 110mm 13G spokes.
But I see the 13G spokes are much thinner then MP3 spokes :o
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Nevermind MP3 spokes are 12G! ::)