Spoke gauge and wheel build question

[safasdf444]

Hi,

I have a Bafang G310 from Grin. I am about to purchase an old mountain bike, 26 inch wheels, V brakes. I would like to have a bike shop install the hub in the existing wheel.

Would they be able to use the existing spokes? Or will I need to get beefier ones for this build. When I chatted with the bike shop the other day, they said their spoke cutting tool couldn't handle thicker ebike spokes and most likely I would need to order spokes from wherever I got my hub motor.

What gauge of spokes would this setup need? Since the G310 is on the smaller side would the existing spokes be ok?

I'm trying to learn a bit so I can understand better when I go back to the bike shop.

thank you!

 

[amberwolf]

I doubt any wheel builder will reuse spokes, even if they were identical lengths for the new hub in the new rim (which they won't be). They may not even be willing to reuse the rim and require a new one to be used, becuase they can't guarantee a wheel built from unknown condition used parts.


FWIW you don't want "beefier" spokes, thicker ones are more likely to fail, not less, because they will require too high a tension for the rim's strength, causing rim nipple hole failure.

If you are willing to look around you can read about this in many many posts here on ES about wheels, spokes, etc.

But if htey are a "real" bike shop that builds wheels, they *should* already know all this, and be able to cut you (or order them from the appropriate place) the correct 14g-15g butted or 13g-14g butted spokes the wheel should be built from, and they should be able to determine the correct length spokes needed.

If they want to use thicker 12g spokes, etc., with an existing bicycle MTB rim, they probably don't know how wheels work, and you should go somewhere else to have it built, or you can learn how to do so yourself easily enough.

 

[safasdf444]

I doubt any wheel builder will reuse spokes, even if they were identical lengths for the new hub in the new rim (which they won't be). They may not even be willing to reuse the rim and require a new one to be used, becuase they can't guarantee a wheel built from unknown condition used parts.


FWIW you don't want "beefier" spokes, thicker ones are more likely to fail, not less, because they will require too high a tension for the rim's strength, causing rim nipple hole failure.

If you are willing to look around you can read about this in many many posts here on ES about wheels, spokes, etc.

But if htey are a "real" bike shop that builds wheels, they *should* already know all this, and be able to cut you (or order them from the appropriate place) the correct 14g-15g butted spokes the wheel should be built from, and they should be able to determine the correct length spokes needed.

If they want to use thicker 12g spokes, etc., with an existing bicycle MTB rim, they probably don't know how wheels work, and you should go somewhere else to have it built, or you can learn how to do so yourself easily enough.

I guess a dumb basic question from me. Do hub motors require special spokes? Or are they same spokes you would use on a regular wheel?

 

[amberwolf]

Well, I already said the size spokes you need in the post, and there are a lot of other posts you can look up that describe in detail why, if you're interested. (no point in repeating it all here yet again)

But basically, wheels built of the same rims need the same spokes, because the spokes required are first based on the rim being used.

Wheel design is more complicated than that, but you don't have to worry about all the details (if you do you can look them up in existing posts, etc), just use the right gauge spokes for the rim being used.

A qualified knowledgeable wheel builder that's going to build a wheel for you will be able to deal with anything else that's different about that particular wheel and usage.

 

[amberwolf]

Some possible searches for detailed info; they don't list all the posts or threads that have info, there are many. Unfortunately due to the nature of the search, it also includes irrelevant posts and threads.
https://endless-sphere.com/sphere/search/2232305/?q=spoke&c[title_only]=1&o=date
https://endless-sphere.com/sphere/search/2232305/?q=spokes&c[title_only]=1&o=date
https://endless-sphere.com/sphere/search/2232321/?q=wheel&c[title_only]=1&o=date
https://endless-sphere.com/sphere/search/2232321/?q=wheels&c[title_only]=1&o=date
https://endless-sphere.com/sphere/search/2232346/?q=wheel+build&c[title_only]=1&o=date
etc.

 

[Chalo]

Hub motors are usually drilled for thicker spokes than what the rims need. As a result, when you use 14ga (2.0mm) spokes, you'll have to put 2.0mm flat washers underneath the spoke heads so they don't dig into the hub holes or try to pull through.

 

[docw009]

14G spokes with washers will work per Chalo's comment, but if you look at Grin's web site, I believe they recommend Sapim butted spokes, 13G at the elbow and 14G at the wheel, Bike shops ought to have a spoke cutter that can handle 14G.

There you go, Go to the shop with either option.

 

[safasdf444]

14G spokes with washers will work per Chalo's comment, but if you look at Grin's web site, I believe they recommend Sapim butted spokes, 13G at the elbow and 14G at the wheel, Bike shops ought to have a spoke cutter that can handle 14G.

There you go, Go to the shop with either option.

I just learned something, Thank you!

 

[gromike]

Check out Grin's spoke length calculator, Online Spoke Calculator for Hubmotors and Ebikes.
And watch their motor wheel building tutorial toward the bottom of this page, Wheel Building - Learn .
I built 3 motor wheels with Grin's guidance.
Wheel building, at least single crossed spokes, isn't all that difficult. Kinda a pleasant evening thing to do. Money saving, though, it's not.

 

[glennb]

They're drilled for 13G.

 

[glennb]

Photo is two cross in 27.5 rim (584mm).

For a 26" wheel I'd only go single cross.