How should ebike wheel design change?

[ebike4healthandfitness]

Now that ebikes are very common (particularly pre-built ebikes with machine built wheels) it would seem to me that the tradition of them borrowing classic 36 spoke wheels/rims from pedal bikes should be reconsidered.

First of all, even the smallest geared hub has a lot more space on it for spoke holes than the typical pedal bike hub (which usually has a PCD of around 45mm for the rear hub and because of this is limited to more or less 36 2.5mm diameter spoke holes).

Secondly, I'm seeing a lot of new bicycle rims now sporting machined out sections for the purpose of lightening the rim. Why not just use additional spoke holes for this purpose also? Even the super high spoke count "low rider" bicycle wheels I have seen still have room for a shrader valve despite the massively increased density of spokes added to the rim.

Thirdly, straight guage are really cheap and if enough of them are added it has the same effect of sharing the load as stiffening the rim or using thinner double butted spokes.

P.S. Something I noticed while checking prices on quality stainless steel spokes was that 15 straight guage was always cheaper than 14 straight guage. The 15 straight guage was usually 55 cents each compared to 75 cents for 14 straight guage. This in comparison to both 13/14 single butted and 14/15/14 double butted which were usually a dollar each.

 

[calab]

32h hubs are available.
Cast rims are a bad idea.

 

[ebike4healthandfitness]

I forgot to mention spoke-nipple line in the opening post. The more spokes that get added then the lower the angle deviates from 90 degrees at the rim whenever 1 cross or better lacing gets used.

For example, 36 spokes and an Alex DM24 laced to a direct drive hub with PCD of 232mm comes out to be 76 degrees for 1 cross. Increase spokes to 48 with the same rim and hub and now 1 cross comes out to be 79 degrees. Increase spokes yet again to 64 and 1 cross comes out to be 82 degrees which is 1 degree past the entry point of the ideal range of which 90 degrees is perfect.

Alternatively (and I think a better idea), the spoke holes on the spoke bed of the rim could be drilled at an angle. It would allow 2 cross or better lacing to still have a fairly straight or very straight spoke nipple line while at the same time allowing better transmission of torque from the hub through the spokes to rim.

 

[ebike4healthandfitness]

How do people feel about using a high spoke count of 15 straight guage on a rim with a spoke bed drilled at an angle good enough to allow for 3 cross lacing (or better) and yet still have a straight enough spoke nipple line when using a direct drive hub with the standard PCD of 232mm?

I reckon it would be fairly economical to make as well especially if a machine can lace it.

P.S. 48 15 straight guage spokes gives a bit more stiffness than 36 14 straight guage spokes for about the same money. However, this is still pedal bike territory. For ebikes I think we need at least as much stiffness as 36 13 guage spokes at the entry level. In order to get to that level of stiffness you would use 64 15 straight guage spokes. In order to get to the level of stiffness of 36 12 guage spokes you could use 72 15 straight guage and come within 96% of that stiffness. Easily obtainable on any electric hub and bicycle rim assuming you can get them to make the drilling. With that said 72 holes can be found on bicycle rims in various widths. I can even get bicycle rims in 144 hole (which is obviously overkill). Some fat bike rims have 64 holes and Phil Wood even made a 64 spoke wheel (see attachment below) out of one of them using one of their bicycle hubs designed with two rows of spoke holes (one row elbows in and the other row elbows out) on each flange. It's mainly just the electric hubs holding things back.

 

[lnanek]

Some companies are switching to mag wheels. Like the Rattan LM-750 vs. their 750 Pro model. Makes sense, most ebikers are on roads and don't need the flex of spokes. The off road folks prefer mid drives anyway.

 

[richj8990]

There is no need to modify hub drive wheels if the offshore (Asian) companies continue to sell the $500-1800 ones like crazy. There is only change when there is a demand for change. That's why the hub drive and mid-drive markets have already separated so much just in the last several years. Because mid-drive owners and prospective ones often demand a certain standard for the rest of the bike; most hub drive owners simply accept whatever comes with the rest of the bike, especially when the complete e-bike is sold for under $1500 USD. There is no need for those distributors to change anything when they keep selling more and more cheap bikes year after year.

 

[A-DamW]

Cast rims are a bad idea.

Low quality/chinesium yes, bad idea.
I have a number of mopeds/motorcycles/automobiles with cast rims(no chinesium), work just fine.
Only downside might be additional weight, upside massively reduced maintenance.

 

[ebike4healthandfitness]

Some companies are switching to mag wheels. Like the Rattan LM-750 vs. their 750 Pro model. Makes sense, most ebikers are on roads and don't need the flex of spokes. The off road folks prefer mid drives anyway.

Yes, I've seen mag wheels replace spoke wheels but so far its (mainly) only on the 20" ebikes commonly with fat tires (which are very popular in general). Bafang even has "integrated mag wheel hub motor" in 20" fat tire size as one of its options for its latest 1000 watt geared hub motor ----> Bafang Unveils the New H720 Rear Hub Motor eDrive with Automatic Dual-speed Shifting – ebikes Int'l

Variants of this mag wheel 20" fat bike 1000 watt geared hub motor can be seen on bikes like the Juiced hyperscorpion and Juiced hyperscrambler. One downside of these bikes with mag wheels is weight. Juiced Scorpion weighed almost 110 lbs though obviously this wasn't solely because of the mag wheels. With that noted I do wonder how much weight saving could have been had if the mag wheels were replaced with 64 spoke or 72 spoke 20" fat bike wheels?

 

[calab]

Hub motor manufacturers are cheap, cutting corners to make a buck.

 

[999zip999]

And reseller's are aggressive on Alibaba as I have gotten more than 18 people trying to sell me all kinds of motor packages after I bought a kit and a contact me multiple times and it's hard to get rid of them. I guess the economy is going downhill in China right now with 20% unemployment. They're getting cutthroat and things might even be getting cheaper as they probably have overstocked warehouses of hub motor kits. As it seems we've got a little oversaturated with e-bikes after the epidemic.

 

[ebike4healthandfitness]

Hub motor manufacturers are cheap, cutting corners to make a buck.

Not GRIN.

They make their direct drive hub motors on location at their warehouse in British Columbia Canada.

I'm thinking 64 hole GRIN all axle fat bike rear hub using a slower wind version of the made in Canada 45mm magnet Grin Marine Motor would be perfect.

Since all the 64 hole fat bike rims I have seen (including the carbon ones) have 32 holes mirror imaged to another 32 holes on the opposite side of the rim (see Surly My Other brother Darryl as an example) it makes sense to have the same arrangement on the GRIN hub. This arrangement would also allow the GRIN hub to be used as a conventional 32 hole hub (by not using the mirror imaged holes on the opposing flanges) as well as a paired hole 32 hole hub when the appropriate holes are selected on each flange.

 

[calab]

Isn't it the more spokes you got the cooler you are?
More is better!

 

[ebike4healthandfitness]

Isn't it the more spokes you got the cooler you are?
More is better!

Why don't you like about having 64 spokes? Give us your concerns?

 

[calab]

Cost, strength, availablility, adaptability

over looks