Help! My next project

[Benjahmin]

Well tight wad has won out, so I've decided to go with what I've got.
First was scavenging the rim from a defunct Ezee motor case:


Having removed the spokes I've used the Ryan method of finding the ERD. I tightened nipples onto two old spokes so they would not move. Cut off the j bend and cut and file the spokes to the same length. In this case215mm. Insert the spokes into opposite holes and measure between the two ends, 172mm. Then add the lot together to get ERD, 215+215+172= 602.


Next stop will be Grin Technologies site to remind myself on how to measure the hub motor to get spoke length and offset.
So to spokes and the much debated 'What diameter?'. Remind me is it 12 or 13 guage? I favour Sapim super strongs if I can get them.

 

[saneagle]

Well tight wad has won out, so I've decided to go with what I've got.
First was scavenging the rim from a defunct Ezee motor case:
View attachment 63359

Having removed the spokes I've used the Ryan method of finding the ERD. I tightened nipples onto two old spokes so they would not move. Cut off the j bend and cut and file the spokes to the same length. In this case215mm. Insert the spokes into opposite holes and measure between the two ends, 172mm. Then add the lot together to get ERD, 215+215+172= 602.
View attachment 63360

Next stop will be Grin Technologies site to remind myself on how to measure the hub motor to get spoke length and offset.
So to spokes and the much debated 'What diameter?'. Remind me is it 12 or 13 guage? I favour Sapim super strongs if I can get them.

That's a lot of work to get a simple measurement. I just measure the diameter in two directions and add 5mm.

 

[harrys]

"Having removed the spokes I've used the Ryan method of finding the ERD. "

I like that method. I have some straight spokes that I bought by mistake. Would be a good use for them.

On my last wheel, I used the ERD on the seller's website. Normally, I don't mind if they are a bit long, because I use double wall rims and can add washers too. These .
spokes were so long, they poked past the upper wall.

 

[Benjahmin]

That's a lot of work to get a simple measurement. I just measure the diameter in two directions and add 5mm.

Well there ya go. Experience wins out. Sometimes you've just gotta do it the hard way to see the easy way !

 

[Benjahmin]

The Grin spoke calculator is giving me left spoke length 241mm and right 240.1, so I'm thinking 241 all round.

Online Spoke Calculator for Hubmotors and Ebikes

Our handy spoke length calculator allows for easy calculation of spoke length for custom builds - and is the only one of its kind to include paired spoke holes in the flange as is common with many large diameter hub motors. It also creates an automatic side view drawing of the laced wheel and...

ebikes.ca

 

[saneagle]

Well there ya go. Experience wins out. Sometimes you've just gotta do it the hard way to see the easy way !

What about you try it my way and see if you get the same result or how close it is? I've never done it the proper way so I'd be interested in whether there's any difference.

 

[Benjahmin]

OK, measured it as 598 +5 = 603 against Ryans way of 602. Near enuf methinks.

 

[Sturmey]

........ Remind me is it 12 or 13 guage? I favour Sapim super strongs if I can get them.

Looking at your hub in the spoke calculator you posted above, you have a large dish/offset of 9mm and a spoke tension ratio of 32:68. I would use the lighter 14 gauge rather than the heavier 12 or 13 gauge as there wont be enough tension on the disc side to properly tighten the heavier spokes if you use them.

 

[Benjahmin]

Yeh, definitely leaning towards single butted, so 13 g at the hub down to 14g for the spoke.

 

[saneagle]

OK, measured it as 598 +5 = 603 against Ryans way of 602. Near enuf methinks.

Thanks for that. It's well within the boundary of measurement error.

Yeh, definitely leaning towards single butted, so 13 g at the hub down to 14g for the spoke.

I always use straight 14g and never had any problems. You get a better angle out of the spoke holes.

 

[Sturmey]

Yeh, definitely leaning towards single butted, so 13 g at the hub down to 14g for the spoke.

The picture below helps to explain why 14g at the j bend may be stronger than the thicker 13g. When the spokes are newely fitted, there is a gap at the spoke flange. With the lighter and more flexable 14g spokes, this gap disappears when the spokes are tightened and pre-stressed ( checked and re-tightened if necessary). Those stainless steel 13g j-bends spokes are very stiff and have difficulty bedding in at the j bend. This means that there is movement and eventually fatigue at the j bend. This in my view explains why the lighter 14 g spoke may give better service and why I would keep away from 13g (even butted) if possible.