GoldenMotor.com Forum
General Category => Magic Pie & Smart Pie Discussions => Topic started by: Andrew on December 21, 2012, 08:19:36 PM
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Seasons Greatings everyone :). I am currently doing yet another bike build. I have been doing a bit of mountain and forest riding on a hard tailed bike but have decided to build a full suspension bike.
I want to re-lace my pie motor into a mavic heavy duty rim. I have the pie spokes ready, but just need to know if I can do a straight rim swap. The effective rim diameter of the mavic rim is about 538mm if you include the the rim thickness. Or about 534mm if you just measure eyelet to eyelet.
I hope that makes sense. Anyone have the measurements at hand for a GM 26" rim
Also, will pie spokes fit through a normal wheel eyelet? Are the pie spokes 12 or 13 gauge?
Rgds
Andrew
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Why don't measure the rim by yourself?
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Good question. I will have to take apart the current wheel / motor/ spokes to measure the rim accurately. I would rather find out I can replace the rim and purchase a new one before the current wheel is in bits with no replacement at hand.
My main concern is the mavic rim I want to use has slightly off-set eyelets, and I also need to measure the pie spokes gauge to make sure they will fit through the eyelets of the new rim.
I just thought that Alan may have a GM rim diagram ;)
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Mavic nipple eyeles are 14G, but you can buy 14G nipple to 13G spoke.
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I just thought that Alan may have a GM rim diagram ;)
Sorry Andrew, but I only have a built up wheels too, and the measurements I took for my diagrams were not that accurate. :(
Check out this video (http://www.youtube.com/watch?v=7-QZazAY0cc&list=FLrk4r5i3g-DL9zFJ34P3AbA&index=13) regarding nipple clearance in the rim.
Alan
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Waauww that's too much work.
You can buy 13G nipple to 12G spoke.
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Both of your suggestions seem like a good way to go. Filing down a £45 rim will take a little bit of courage, though it is possible.
The photo here shows a wheel build I did recently with a downhill mivic rim. I had the spokes made by tiller cycles.uk. And I am sure they were 13 gauge sapim spokes. I will need to check, though going out in my cold damp garage is not too appealing at present.
(http://www.arhservices.co.uk/apaclark/3F4BDEA4-F89F-4B72-98DF-36806696D410-15686-00000CEA8C7019E4.jpg)
14 to 13 nipples sound like a sensible idea. I wonder where they can be got?
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Well I have bought them from a Dutch shop.
But I think in UK you can also find them.
http://www.sapim.be/nipples/brass/reduction
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Thanks for that.
Are the pie 2 spokes 12or 13g ?
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I don't know my Magic Pie 3 spokes were 12G.
But just measure them? 12G = 2,6mm.
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I have no digital device to mesure the spokes. :(
And, I think I had reduction nipples for my last wheel build. 13g sapim spokes with a 4mm diameter nipple rather than a 5mm.
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I have just purchased an ebay digi caliper, been needing one for a long time :D
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Aaha while it's quite simple, you can see with your eye 12G is much thicker then 13G.
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Thanks for those words of wisdom ;D. Ha ha
Right then, Ventured out to my garage to find it covered in puddles of water from the constant rain finding its way under the old wooden side door ::). The pie spokes I have are definitely not more than 2.3mm, in fact they seem a touch thinner than the 13g spokes I had made. Te nipples are definitely 4mm wide so they will fit in a mavic rim eyelet 8)
Only problem, I think the pie spoke lengths may be a touch too short more a mavic rim ERD. The GM rim has a deep V-shaped cross section so the ERD at a guess is only 325mm. The mavics are around 335 to 338mm. This leaves a lot of excess space at either end of the spoke radius. That is around 5mm extra spoke length needed. It will be a tight fit... Lol. The spoke threads a 10mm max.
If I can get some PIE 2 motor measurements I can try and work out the spoke length suggested by a spoke calculator.
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Hahahaha
Yeah save your money and time and don't use those spokes.
Sapim is much better..... :)
Which model of Mavic rim do you have?
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I am looking at getting either the ex729 or ex719. I have a 729 already and it is very rigid. Both are for downhill mtb and will take upto a3" width tyre. :). I was hoping to save some money and use a brand new set of Magic Pie spokes and nipples I have. They have a maximum usable length of 119mm, minimum 110mm
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Are the pie 2 spokes 12or 13g ?
I've just measured my MPII and MPIII spokes and they are both ~2.3mm diameter, which according to the Sapim site is 13G:
14G = 2,0 mm
13G = 2,3 mm
12G = 2,6 mm
The MKI Pie used longer 12G spokes with 13G nipples:
(http://www.arhservices.co.uk/GoldenMotor/MPIMPIIspokecomparison.JPG)
If you need to use new spokes of a different length, you might want to consider using butted spokes (http://www.sapim.be/spokes/butted/strong) which are 13G at the hub end and 14G for the rest of the spoke and nipple.
If I can get some PIE 2 motor measurements I can try and work out the spoke length suggested by a spoke calculator.
That's not a good idea because spoke calculators assume the spoke are equally spaced around the hub, but the MPII and MPIII uses an unorthodox spacing pattern which the spoke calculator will not allow for.
If you place your wheel horizontally on the floor, you can then hang a plumb-line against the inside of the rim (or perhaps a set square?) and mark the floor where it touches, and then repeat on the opposite side (180 degrees apart) and then lift the wheel away and measure the distance between the two marks on the floor.
You will also need to consider the length of the nipple sticking out of the two rims, as I suspect it might be inset further due to the eyelets on the Mavic rim.
Example
If the Mavic rim inner diameter is 8mm larger than the GM rim, then the spokes will need to be at least 4mm longer.
If the nipple protrusion is 2mm less on the Mavic rim, you will also need to add an additional 2mm to the spoke length.
So, if the pie spoke was 110mm long, the required spoke length for the Mavic rim will be 116mm.
If the spokes you have are only slightly too long, you might still be able to use them. If you lace the wheel so the spoke heads are on the inside of the hub flanges and the spokes on the outside, it will make a much stronger wheel and also support the spoke elbows much better where they attach to the flange, and should take up some of the additional length.
(http://www.arhservices.co.uk/GoldenMotor/Spokegap.JPG)
Here's my Pie with the spokes re-fitted on the outside of the flange as described above:
(http://www.arhservices.co.uk/GoldenMotor/ReversedSpokes.JPG)
Alan
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That is some excellent advice about having the spoke elbows on the outside of the flange so they sit tight against the flange edge. :D
As for the pie spokes, with all things considered I think they will be too short. The maximum usable length of 119mm includes the nipple up to the base of the head with the nipple only just screwed to the thread. Wishful thinking, but still maybe worth a go before I purchase longer made spokes.
Alan, thanks as always for giving up the time to demonstrate things so thoroughly.
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Still I don't know why the people of GM install spokes in the wrong way!
The countersink hole is just for preventing spokes to brak when the spokes are laced in a angle.
The countersink hole is not for spoke head.
The only good way to lace the spokes are in second picture!
Also I did have a look at my Magic Pie 3 both side inner and outer has countersink holes.
I think they should thinking before drilling......