Questions about ebike rims

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ClintBX

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Hi ESFMs,

I had to take the motor's core out of one wheel and put it into another late last night because there was a crack in my rim.

Lucky for me, I had a spare hub wheel.

This is the second time that my rim splits on me in the past year and a half.

Anyway, I'm shopping around for a new rim (should this happen again, I want to be prepared) and I need to know what I should look out for.

I'm riding with 26" with a 2.2 cm tire. I'm not 100% certain what width rim I should get.

Also, after doing a quick search, I keep finding rims that say not compatible for rim brakes. And that's a problem for me because rim brakes is the only option on my ebike.

And last question, are there any steel rims on the market and where can I get them. I can only find aluminum or carbon fiber out there.

FYI, I'm riding with a 1200 watt motor on a 48 volt system. I forgot what the weight of the motor is but it feels like a hefty 3 or 4 kgs. Maybe 5 kgs.

I ride quite a lot everyday. I probably do anywhere between 50-100 kms, so I would like a rim that has a long life that is also compatible with rim brakes.

I will post pictures of what I've got soon.

Clinton
 
If your wheel has 12ga (2.7mm) spokes, that's probably why it cracked. If you're going to the effort of relacing your wheel, use 14ga (or better, 14-15ga butted) spokes, with washers under the spoke and nipple heads if necessary. Thinner spokes help the wheel stay tight, prevent rim cracking, and allow the wheel to carry a heavier load without problems.

Steel rims are weaker than aluminum rims until they are 3 to 4 times heavier. There are no double walled steel rims.
Don't even bother. Steel rims suck.

Get a rim with at least 24mm inside width, double walled, with eyelets if possible, and as heavy as you can find. Weinmann DM30 is a cheap and widely available rim in that category. Sun MTX39 is a very strong rim, but it does not work with rim brakes (only disc or roller brakes).

Luna Cycle still lists the excellent Alex DM24 rim for only $20. Everybody else seems to have run out of stock of this strong and versatile rim.
 
Most 26 in DH rims are a good choice

I use a Alex DM24 with Sapin 14/13g butted stainless steel spokes. It is very strong and have had no problems in 15,000 km

You mentioned your tire is 2.2 cm rim26_dm24_inside_1_2.jpgdid you mean 2.2 in ?
 
Alex DM24 has note above, or Velocity Cliffhanger (about 4 to 5 X the price).

Agree with 13/14 or 14/15 butted spokes.

If (when) my 622 rear hub rim fails, I plan to use Cliffhanger rim with 18 spokes on the non-drive side and 36 spokes on the drive side, with Wheelsmith DB14 spokes. I will have to drill and extra 18 holes in the rim and hub.
 
nfmisso said:
... I plan to use Cliffhanger rim with 18 spokes on the non-drive side and 36 spokes on the drive side, with Wheelsmith DB14 spokes. I will have to drill and extra 18 holes in the rim and hub.
Click to expand...

What? Wouldn't that make the rim really unbalanced?

Never heard of such before. I'm intrigued. Please share info about this setup.
 
RageNR said:
nfmisso said:
... I plan to use Cliffhanger rim with 18 spokes on the non-drive side and 36 spokes on the drive side, with Wheelsmith DB14 spokes. I will have to drill and extra 18 holes in the rim and hub.
Click to expand...

What? Wouldn't that make the rim really unbalanced?

Never heard of such before. I'm intrigued. Please share info about this setup.
Click to expand...

Not really, even on ebike, there is a significant difference between DS and NDS loads. On my non-electrified bike with 559 rim (26" mtb); on the rear I run 40h, with Wheelsmith DB15 spokes on the NDS, and DB14 spokes on the DS. This results in about the same tensile stress in all the spokes, because there is less tension force in the NDS spokes due to the flanges not being symmetrical about the center line plane of the wheel. The DB14 spokes have a bit less than 1.5x the cross sectional area in the thin sections compared to the DB15 spokes. The 36 DB14 on the DS with 18 DB14 on the NDS is 2x difference, which can be somewhat mitigated with cross patterns.

To determine the relative tension force between the DS and NDS sides, is strictly a matter of trigonometry. They have to provide equal and opposite side to side force, and unlike a non-disc brake front hub, the flanges are not symmetrical, so there will be different tension forces (and radial forces) to achieve the equal side to side (axial).

I haven't done the measurements and calculations yet on my wheel, and it may turn out that I should use 18x DB14 on the NDS with 36x DB15 on the DS. If I am lucky, I will not be doing this for a little while..... :)
 
nfmisso said:
RageNR said:
nfmisso said:
... I plan to use Cliffhanger rim with 18 spokes on the non-drive side and 36 spokes on the drive side, with Wheelsmith DB14 spokes. I will have to drill and extra 18 holes in the rim and hub.
Click to expand...

What? Wouldn't that make the rim really unbalanced?
Click to expand...

Not really, even on ebike, there is a significant difference between DS and NDS loads. On my non-electrified bike with 559 rim (26" mtb); on the rear I run 40h, with Wheelsmith DB15 spokes on the NDS, and DB14 spokes on the DS. This results in about the same tensile stress in all the spokes,
Click to expand...

To be specific, it means the left side spokes only need to have about 79% as much tension to stretch the same amount as the right side spokes. That's assuming 1.8mm center diameter versus 1.6mm center diameter right/left, which might not be exactly Wheelsmith diameters.

For your own wheel, you could stick with 36 spokes, and use 14ga straight or 13-14ga single butted on the flatter side, and 14-17ga Sapim Laser or DT Revolution on the deeper side. The thin spokes would give the same amount of strain as the thick ones with only 56% as much tension. That's almost as good as using twice as many on the tight side. But it's a lot simpler to implement.
 
As stated above, the Alex DM24 are strong and cheap. I prefer the Sun Rhyno Lite which aren't much more expensive than the DM24's. I can confirm they're compatible with rim brakes. There's also the Rhyno Lite XL's which are stronger with a welded seam vs the pinned seam of the others.

I built some strong wheels using some nice Sapim 13/14 black spokes in 20" and 26" sizes with yellow rims and damn they look sweet. The 12g spokes that come with most hub motors are made with a patented extra-extra-cheap Chinese jello-alloy that results in stretched threads that jiggle loose.
 
Chalo said:
If your wheel has 12ga (2.7mm) spokes, that's probably why it cracked. If you're going to the effort of relacing your wheel, use 14ga (or better, 14-15ga butted) spokes,
Click to expand...

How do I measure my spokes? Is that 2.7mm in diameter?
And are you saying to go for thinner spokes? That seems counter intuitive.
 
The spokes need to flex and keep tension. When 12 ga are too stiff for the rim, they make it break, they can pull through, or crack it. Brake wear too, can crack a rim.
 
bionx 1954 said:
You mentioned your tire is 2.2 cm rim26_dm24_inside_1_2.jpgdid you mean 2.2 in ?
Click to expand...

I definitely meant 2.2cms. I'm mainly referring to the side of my tire. I have a maxxis holy roller 26 in x 2.2 cms. Yeah, I just realized now, tire measurement are using 2 different systems. That's just whack. 🙃
 
Most Maxxis Holy Roller are 2.4 inch wide. That is what the second number means in 26 X 2.40

The other standard measure is ETRTO 61-559, that means it is 61mm wide, 559mm dia

There are some that are 2.20 inch, but not common, here at least.

The ideal rim width for a Holy Roller is 40mm, 30 to 47mm are good choices.
 
ClintBX said:
Chalo said:
If your wheel has 12ga (2.7mm) spokes, that's probably why it cracked. If you're going to the effort of relacing your wheel, use 14ga (or better, 14-15ga butted) spokes,
Click to expand...

How do I measure my spokes? Is that 2.7mm in diameter?
And are you saying to go for thinner spokes? That seems counter intuitive.
Click to expand...

Yes, that's 2.7mm in diameter, versus 2.0mm for 14ga spokes. 1.8mm for 15ga spokes.

The strength of a wheel is in its rim, not in the spokes. The more you load the wheel, the more the rim flexes. The thinner the spoke, the more it stretches when tight and is able to track the rim's flex without becoming slack.

Important in your case, a thinner spoke doesn't place as large a force on the hole drilled in the rim as a thick one does, when the wheel gets a shock.

You can think of it as counterintuitive, but a thin stretchy spoke that stays tight all the time makes a more reliable wheel than a thick stiff one that goes momentarily slack whenever you put a load on the wheel. The thinner a spoke you use, the more load you can put on the wheel before there are reliability problems.
 
I said I was going to provide pics, so here are images of the crack, full shoot of the type of wheel I'm working with and the width of the rim.

Note that I'm measuring the rim's width from the outside. Looks like it's slightly less than 3 cms wide.
 

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MadRhino said:
Most Maxxis Holy Roller are 2.4 inch wide. That is what the second number means in 26 X 2.40

The other standard measure is ETRTO 61-559, that means it is 61mm wide, 559mm dia

There are some that are 2.20 inch, but not common, here at least.

The ideal rim width for a Holy Roller is 40mm, 30 to 47mm are good choices.
Click to expand...

An yeah, you're right. It must be inches. 2.2 cms would be crazy skinny. I don't know why I thought it was cms.

I manage to find a 2.2 in holy roller. The 2.4s are the most common and I didn't want to go too much into the balloon range of tires. (I'm use to 1.95 and 2.00 ins)
 
Dumsterdave said:
Besides Luna, where can I buy the Alex? I'm in Europe
Click to expand...

I haven't found any other source for 26", 36 hole Alex DM24 rims lately.

Here's one that should be at least as good for your application:
https://www.sjscycles.co.uk/rims-tape/36-ryde-andra-40-26-559-rim-black/
 
Dumsterdave said:
Besides Luna, where can I buy the Alex? I'm in Europe
Click to expand...

And I'm in Australia. I was looking at rims on a Canadian site but the cost of shipping was the price of a new hub motor and wheel combined.

What are my options?

Anyone know an Australian based vendor? Or maybe China (because of the cheap shipping)?
 
Chalo said:
Dumsterdave said:
Besides Luna, where can I buy the Alex? I'm in Europe
Click to expand...

I haven't found any other source for 26", 36 hole Alex DM24 rims lately.

Here's one that should be at least as good for your application:
https://www.sjscycles.co.uk/rims-tape/36-ryde-andra-40-26-559-rim-black/
Click to expand...

This link is s from the UK. The shipping cost to Australia is double the price of the rim. £55. The Ozzie dollar is not strong, so that's like A$80 I'm guessing.
 
I had the same problems trying to get a rim online here in Canada . I found a local bike shop that does wheel building and got a Alex DM21 for 30.00 cdn also Sapin 14/13 spokes . You need a 26 in down hill double walled, 36 hole, rim brake compatible rim. Most good brand name rims are ok.
 
I am in Canada, yet most of the time I buy rims in Germany. The trick is to buy many at once, with tires and other maintenance parts that you will need. Shipping overseas for one rim alone, often double the cost if customs does add fees. That is why I keep a lot of parts on the shelves, never on a rush to order anything.
 
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