NEEDED : spoke info for MAC 10T in 26" DM 24

javi

10 mW
Joined
May 23, 2014
Messages
20
Location
Wisconsin
Hi,

I am moving my Mac 10T motors from 700c wheels to 26" Alex DM 24 Rims. I am having a wheelbuilder put it together, but I need to order rim/ nipples, and spokes. I looked at the GRIN SPOKE CALCULATOR, but I couldn't find MAC hub and it is a little over my head.

Can anyone out there provide a list of what size spokes and nipples will work best for this?

Also, if anyone had a picture of a complete wheel for this set up, that would be great. I can give this to wheelbuilder and he will see how to configure.

Thanks!
 
I wouldn't trust a wheelbuilder who couldn't figure this out himself although he may not know about danscomp for custom spokes (phone - don't order from the site). Alex produces decent rims and most will suggest 25 mm or so width. Your frame probably isn't designed for disc brakes so you need to sort that out too. You can have a mount welded to the frame, if desired.
 
I am sticking with stock brakes for now (V-brakes)

My wheel builder could figure it out, but the deal I made with him was that I would supply him everything and he would lace it up. He does it as side business now and it would cost me more if he had to figure out things and order things. He was bike mechanic for 10+ years and used to work as mechanic for racing teams as well. He is good friend and says he builds a good wheel and he is reasonable - He is charging me $40 to build two wheels...

I will have him figure it out if necessary, I just thought this was a rather common combo, so I figured someone on here would have the spoke info...

These are rims I was planning to use - http://www.amazon.com/Alexrims-DM24-Mountain-Downhill-Silver/dp/B001CJV76O
 
Rim ERD is 547 so you just need the motor flange diameter hole-hole and plug that in.

I'm on a mobile device so unable to dig up Mac flange diamter but you could just measure the one you have and plug that into the spoke calculator? Or look around for drawings, they're out there.
 
Ykick,

Thanks for ERD, but I am finding different info...

On Alex site is says 543 -http://www.alexrims.com/product_detail.asp?sc=0&cat=22&pid=83

On Cheap Bike Parts is says 546 - http://www.cheapbikeparts360.com/products/alex-dm-24-26-rim/

I have found others that say 547 like you say. That is one reason I was hoping to find someone who actually built this wheel and knew what spokes worked just so I could be sure...
 
A single millimeter is quite small, so some disagreement is acceptable. If using a double-walled rim, it is better to get spokes that are one mm too long, rather than one mm too short.

The MAC spoke flange pitch circle diameter on record (PCD) is 172mm

"The wheel-building spoke-lacing thread, post your tips" (spinningmagnets, 5 pages)
http://endless-sphere.com/forums/viewtopic.php?f=2&t=64324

"MAC geared hub specs, teardown, and pics"
http://endless-sphere.com/forums/viewtopic.php?f=16&t=51310
 
I think mine is in a dm24. 26inch rim. My thread mentiomed the spokes i used and length. Really cheap but when tensioned proprly no problem. Probably use as a cross check that you cslculate correct spoke length.
http://endless-sphere.com/forums/viewtopic.php?f=2&t=56111

Also got spares from cellman and about 2mm difference between left and right spokes but the ones i used are equal length znd work fine.
 
I built a regular front wheel with 26" DM24 last year and used 547 for my ERD calculations. Different hub of course but everything fit as expected.

1-cross motor wheels are surprisingly simple, if not "easy" to lace. I suggest do the assembly yourself and maybe let your friend true it up? Wheels/tires are right behind Batteries in the priority department, IMO. You'll be much better off if you learn how to work with laced wheels.

Personal experience over 12 wheel builds, I would rather be 1-2mm short than 1-2mm long. Damn hub motors often require so much dishing it's easy to get too much spoke poking the tube on one side. Yes, you can play with different lengths on each side but it all gets to be much ado about nothing. Build it, true it, ride it, ride it some more, if it rarely needs any additional truing, you've built a good wheel.
 
Thanks for all the replies and info.

I went in and did the spoke calculator at Grin - I wasn't sure about dish, so I put in (-10) and it spit me out 195.4 (left) and 193.9 (right). I used 547 ERD and 172 for flange diameter. That matches pretty closely with what others have reported here, so should be good to go.

Ykick - thanks for encouraging me to lace up the wheels - I will probably do that. I was planning on doing the whole thing until my friend gave me such a reasonable price. I will probably attempt some front rims in the near future myself.

Does anyone out there have an opinion about the dish for this combo?

Thanks!
 
I suppose wheel building techniques differ greatly from one person to the next. But measuring effective rim diameter (ERD, the span across a rim) is an important element in wheel building in my opinion. My understanding is that the ERD can be different simply from one rim to the next of identical brand and model for various reasons.

How I measure ERD is I accurately cut a pair of spokes to 200mm(this cut removes the elbow section, length from the threads down, I use 100mm lengths for smaller wheels) and then tape(http://www.amazon.com/gp/product/B001E5ZWT4/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B001E5ZWT4&linkCode=as2&tag=xbnijgbr-20&linkId=W2KBASRSEXHJQ4ZE tape I used) a rubber band to each end of the non threaded side. I put the threaded sides through the opposing rim spoke holes with nipples screwed into the depth I see fit. I measure the gap between the ends of the spokes and then add 400 to this number. A great tool for accurately measuring the cut spokes and the gap between ends of the spokes when measuring ERD is one of these http://www.amazon.com/gp/product/B000EJUBBU/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B000EJUBBU&linkCode=as2&tag=xbnijgbr-20&linkId=FEOLOKZJ5M4YXMOT , this is the particular one I use. Great tool to have for many things. I suggest measuring the ERD 3 times and using the average of that number.

You might be able to get your friend to calculate the spoke length for you, or maybe he can just answer your questions as well, I'd ask him either way. He might show you have exactly he measures ERD.

I could be wrong in thinking it's important to accurately measure the ERD for every rim, but I am a stickler for detail. "The devils in the details." I imagine that the detail of ERD might be as important as entering the correct flange spacing measurements. Everything sort of hangs together when calculating spoke length. "The only difference which makes no difference is no difference."


One thing others may have mentioned but I missed, there are spoke thicknesses of many varieties. You probably want to get single butted 13 gauge(2.3mm)/14 gauge(2mm) spokes, which means 13 gauge (thicker) at the elbow and 14 gauge(14g) beyond the elbow and a little bit thinner. Some think it's better to go thicker, spokes need to stretch under tension to retain their tension, the stretching helps preventing the nipples from turning when you go over hard bumps as you travel. A thicker spoke will need more tension to stretch enough for this effect than a thinner spoke will, a bicycle rim probably cannot handle the tension needed to appropriately stretch some like straight 13g and thicker spokes, this is why we would probably use 13g/14g spokes or thinner. The best value for you is probably 'sapim strong' (sapim is a brand, strong is a product) spokes with sapim polyax brass nipples.

In summation, there are a lot of little details that go into wheelbuilding, more than just calculating spoke length. If you are going to indeed hand off the unlaced components to someone else then it's probably not as important that you seriously take some time to read a few books on the subject, but it certainly wouldn't hurt.

http://www.sheldonbrown.com/wheelbuild.html
http://www.wheelpro.co.uk/

Might be good sources of knowledge on things for the process.
 
bowlofsalad said:
I suppose wheel building techniques differ greatly from one person to the next. But measuring effective rim diameter (ERD, the span across a rim) is an important element in wheel building in my opinion. My understanding is that the ERD can be different simply from one rim to the next of identical brand and model for various reasons.

Maybe 50 yyears ago; but not today. The QC of any decent rim manufacturer will not let anything like that out the door. I bet you could measure 1000 Alex DM24 rims and they would all be within 1mm of each other and that is not going to affect anything in the way of spoke calculations.
 
I never take any notice of published ERDs. Instead, I measure the the inside diameter and add 5mm. That works very well for double-walled rims.
 
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