26" 36H rim for Crown motor

[motosen]

Greetings

I have been running with Mavic EX823 now over 7 years and the nipple inserts starts to brake and gets stuck to the rim. I would buy the same rim but its so hard work to lace. 12G nipples/inserts must be machined to fit.

What 26" 36H rim would you suggest to ~9.8kW (from controller) motor that has big enough holes for 12G nipples? I use 2.4" wide tire.

Thanks!

 

[amberwolf]

Don't use 12g spokes/nipples. They're too large, and take more tension than the rim can handle, so then the rim becomes damaged and the nipples loosen, so the spokes break. It's even worse if the rim has to be modified (like drilling out reinforcing eyelets, etc).

Use 14g spokes/nipples, which the rim was designed for. It will make a stronger wheel, because the thinner spokes can be properly tensioned, where the thicker 12g can't.

You also won't have to modify the rim/etc, making lacing much easier, and the parts more reliable because they're left as-designed.


If the hubmotor's holes are too large for 14g, then get 13/14 butted, so the head and elbow are 13g, but the rest of the spoke is 14g, which still allows the spokes to be correctly tensioned for the rim.

Sapim spokes are available from Grin Tech and other places, including DansComp, etc.

 

[motosen]

Thanks for the answer. Old type Crown motor has special spokes and they are only available in 12G size. I have not modified the inserts, only the nipples (which hasn't broken even once).

 

[amberwolf]

Thanks for the answer. Old type Crown motor has special spokes and they are only available in 12G size.

I recall seeing those when it came out, and decided against ever getting one of those specifically because I figured that would be a problem. :/

You might check with places like DansComp and other spoke providers to see if they can get spokes like that in other sizes.

There is also this thread:
https://endless-sphere.com/forums/viewtopic.php?t=60320
that may have useful info.

It suggests using common straight-pull spokes, and bending them as needed.

I suspect you could just put the straight-pull spokes in the motor, then bend as needed to fit the specific rim they're on.

I have not modified the inserts, only the nipples (which hasn't broken even once).

Perhaps you could clarify this then:

What are the "inserts" that you're talking about breaking here:

the nipple inserts starts to brake and gets stuck to the rim. I would buy the same rim but its so hard work to lace. 12G nipples/inserts must be machined to fit.

and why do you say that the "nipples/inserts must be machined to fit", which implies that both parts are being machined?

 

[motosen]

Thanks for the answer. Old type Crown motor has special spokes and they are only available in 12G size.

I recall seeing those when it came out, and decided against ever getting one of those specifically because I figured that would be a problem. :/

You might check with places like DansComp and other spoke providers to see if they can get spokes like that in other sizes.

There is also this thread:
https://endless-sphere.com/forums/viewtopic.php?t=60320
that may have useful info.

It suggests using common straight-pull spokes, and bending them as needed.

I suspect you could just put the straight-pull spokes in the motor, then bend as needed to fit the specific rim they're on.

My first option is to buy rim with 12G holes. Here is one example: http://shop.crystalyte-europe.com/product.php?productid=16536&cat=&page=2

I have not modified the inserts, only the nipples (which hasn't broken even once).

Perhaps you could clarify this then:

What are the "inserts" that you're talking about breaking here:

the nipple inserts starts to brake and gets stuck to the rim. I would buy the same rim but its so hard work to lace. 12G nipples/inserts must be machined to fit.

These:

and why do you say that the "nipples/inserts must be machined to fit", which implies that both parts are being machined?

I meant nipples OR inserts must be machined. I have machined nipple extremity smaller. Other option would be to machine insert holes bigger.

 

[amberwolf]

My first option is to buy rim with 12G holes. Here is one example: http://shop.crystalyte-europe.com/product.php?productid=16536&cat=&page=2

Just a note that that page says:

Spoke hole punching : angled (for e-bikes with a large diameter)

yet the only picture clearly shows standard flat eyeletted holes. So I wouldn't believe anything else the page says, either. (not that I believe much of anything that Crystalyte says anyway).

I've had multiple Crystalyte hubmotors that came with rims preinstalled by crystalyte (and more by other manufacturers), and the 12g spokes they think are great (but are too thick for the rims) and every one of the rims failed at the nipple holes, whether they had eyelets or not, because the spokes are too thick for the rim's design and material, so when they are tensioned correctly, the rim distorts at the nipple hole, and over time that cracks it. This releases the tension on the spoke, and the nipple turns, releasing even more tension.

The Mavic rim you have is a slightly different failure mode, in that the inserts are apparently precisely machined for 14g spokes, and too thin to handle the stresses if drilled out for larger ones per this post:
https://www.endless-sphere.com/forums/viewtopic.php?t=59695
but apparently from your experience even when unmodified they still have the same problem as standard insertless rims, when used with spokes that are too large and require more tension than they can have.


Unfortunately I don't have any info on bicycle rims that are designed for 12g spokes (not by having larger holes, but by being engineered to take the extra tension without failing). I'm sure there are some, somewhere...maybe in DH type stuff? I did a little poking around and didnt' find any in the few minutes I had to try, but it doesnt' mean they're not out there.

I meant nipples OR inserts must be machined. I have machined nipple extremity smaller. Other option would be to machine insert holes bigger.

If the inserts are already breaking, the problem would only be worse if you did that.

 

[motosen]

Just a note that that page says:

Spoke hole punching : angled (for e-bikes with a large diameter)

yet the only picture clearly shows standard flat eyeletted holes. So I wouldn't believe anything else the page says, either. (not that I believe much of anything that Crystalyte says anyway).

Yeah that doesn't look the best option.

What do you think about SUNringle MTX 33 and Nimbus Dominator? ERD and width on first option should be fine but its not available anywhere at the moment. If second option has ~35mm inner width it could go with 2.4" tyre, I think. Though not sure about the ERD.

If the inserts are already breaking, the problem would only be worse if you did that.

Yes. I'm satisfied that it lasted this long on hardtail mtb.

 

[amberwolf]

Not to try changing your mind, but for any other readers, just some experiental data about the difference in spoke gauges vs wheel strength:

FWIW, I'm using 13/14g butted spokes (sapim from Grin Tech) on my heavy (500lbs+ with me on it) SB Cruiser trike, for the rear radially-laced 20" wheels with MXUS 450x hubmotors in them, and I regularly carry 100-300lb+ loads in the back over those wheels. It's completely unsuspended, and we have some fairly bad spots on the roads around here. The spokes are very short, so good tension is even more important as there is much less stretch available due to the short length. The rims are wide eyeletted rims of unknown manufacturer or specifications (from Ypedal, originally from "leftovers" from what were supposed to be very early Zero motorcycle parts, when it was really more like a really fast bicycle something like the lower end Surron/etc types)

While I have broken motor axles from various pothole impacts, bent and even cracked bead-flanges on the rims, etc. from those impacts and other road debris, I haven't broken spokes or had them loosen up (except for once when the rim itself was bent enough from impact to do this), and haven't damaged the rim's nipple holes.


Before, I had used regular OEM wheels and spokes, so not very good rims, and the thicker 12g spokes. Primarily this was on CrazyBike2, which also had a 20" rear wheel, but it was a lot lighter (and so was I), probably 300lbs with me on it (can't remember), and much smaller cargo loads (had to use a trailer for most of them). Even so, I'd regularly break spokes because the rims would crack around the nipple holes from too-high-tension.


I also used regular bike wheels, no motors, 15g spokes up to maybe 14g, and the ones that I had problems with spoke breakage were ones where the spokes were not tensioned correctly to start with (where I just used junk bike wheels as-is without checking or tensioning/truing them). This was on all of my bikes over the years, both before I started using motors, and after, and with the various trailers I've used. The trailer wheels were generally always junk and would fail even without heavy loads on them...simply retensioning them correctly before using them would almost always prevent the problems, on all those wheels, even with the skinniest spokes.


I learned about building wheels because I got tired of all that stuff, and the spoke size/tension thing vs the rim type was the most important thing I learned.


The other thing I learned was that "airless / airfree" tires, with the foam inserts, are a really bad idea, because they beat the crap out of the rims, so the rims deform, and then the spokes loosen, and then the wheel falls apart. :/ Doesn't matter what kind of rim or spokes, if you load it anywhere near what you could a pneumatic wheel, it can't handle it.

 

[amberwolf]

What do you think about SUNringle MTX 33 and Nimbus Dominator? ERD and width on first option should be fine but its not available anywhere at the moment. If second option has ~35mm inner width it could go with 2.4" tyre, I think. Though not sure about the ERD.

If the ERD is the same as your existing rim, then the same spoke length would work. If it's not, then you may have issues (there's a pic in one of those posts I linked that shows something from Sapim I think it is).

I haven't used the SunRingle MTX33 rim, but I have an old Sun Rhyno Lite I used on the front of SB Cruiser for some time, and it was used when I got it, and it held up well under various loads and impacts. I cant' remember for sure, but I think it was the wheel that was on the trike in it's only crash, where I broke the fork at the crowns but the wheel itself was intact. (IIRC I wore the hub bearing cups out and ended up replacing the wheel, saving the old one to relace later because I changed to disc brakes anyway).

I don't know if it would handle 12g nipples though, without drilling out the eyelets, which would defeat the engineering of the rim designed to make it strong. (same for any rim--if you modify it to fit something bigger than intended, it may fail because it's not made or used as-designed anymore).


Same for the Nimbus Dominator, on the nipple size and modification issues.

I will say that except for the lack of offset of the nipple holes, the Nimbus looks a lot like the rims I'm using on SB Cruiser on the rear wheels (where almost all the load is). Appearance doesn't necessarily mean anything, but if the source of the rims is that company, then they probably make good rims.


Both of those rims have been brougth up in various threads here on ES before, for strong rim suggestions:

https://endless-sphere.com/forums/search.php?keywords=sun*+mtx&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=nimbus+dominator&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

 

[motosen]

I ordered SunRingle MTX39 because the seller of Nimbus Dominator didn't reply my questions. It has 30mm inner bead width and 535 ERD. My current rim has 534 ERD, which is perfect for the current spokes. I will forget the default 12g spokes and order butted straight 14g spokes and try to bend them. Lets see how does it go. Thanks for the help!

E: This is the only place I've found straight 13/14g butted spokes: https://www.ebay.com/itm/SAPIM-STRO...hash=item3da16980c8:m:mLle2VZ8sLR5lXlZ70pmPlw

 

[amberwolf]

Yojimbo's has been reported as a good shop in previous posts, AFAICR. However, it doesn't show or say that it has nipples with it, so you should make sure it either comes iwth them or that you order those too.

If you have to order those separately, ask if htey will combine shipping, cuz they ought to all fit in one package for the same cost.

You could probably even ask if they can do that bend for you; the info for it is in one of thsoe linked posts up in the thread.

 

[motosen]

Yes, the nipples are sold separately. I asked them about making the bend but didn't get an answer. I received the rim this week, it has actually 525 ERD (supplier also confirmed this earlier). Now have to order the spokes and nipples.