hub motors, have you broken your rim/spokes yet

my friend is on the cusp of buying a hub motor kit. he wants to create an offroad hill bashing semi-motorbike.

ive suggested he gets a cheappy 1000watt brushless rear hub motor kit on ebay like i have done, then overpower it with a better controller, like i have done.

his only concern (not one in my mind) is that the spokes and rim arent up to par.

ive had my hub motor for over 2 years with no problem, but he doesn't see this as a good enough sample size, as i weigh 12 stone instead of his 14-15stone.

if its not too much trouble can everyone please post their weight, how long their hub motor spokes and rim has lasted without breaking and what kind of riding they do on their bike please.
also if you have broken the rim or spokes can you please let me know what you did to do so.

thanks in advance
jim

It helps to have a moped rim, because the spoke holes are angled.

I have read about a surprising amount of success with one-cross spoke pattern using 12ga and 14ga spokes. The thicker 10ga do not have any stretch or flex in them, and they break more than I would have guessed.

Also, rear suspension is a big help. Hardtail frames break more spokes.

Every rider will have his own experience, for every rider has his own riding style, terrain, speed, wheel building skills and requirements.

The bike I ride in mountain trails has its wheels rebuilt every year, sometimes once more during the season after a crash or a square hit.

large diameter rear hub lace

bicycle rims spokes

sucks

almost always added dish

sucks worse



personal 250lb

best components maintenance

begin breaking 5k 7k miles street



nearly trouble free rear hub motor

moped moto supplies

trade off

expensive heavy no rim brake

jimmyhackers said:

his only concern (not one in my mind) is that the spokes and rim arent up to par.

Click to expand...

Most of the kit rims I've seen and owned are inadequate for the spoke gauge used; typically they use 12g spokes on the cheapest bicycle rims they can get, so the rims are not strong enough to hold the spoke tension even under normal usage. (and they generally don't come properly tensioned to start with).

So...I doubt that it would handle bashing wihtout a rebuild, at the least using thinner spokes the rim can actually handle at the correct tension. Might want to buy just the motor, and a good rim designed for such bashing, then use spokes designed for that rim (probably 14g-15g butted or double butted would work best).


I've broken spokes, on those with just normal usage. Worse, the rims themselves cracked around the nipple holes from the tension required to tighten the spokes enough to have a usable wheel, and so the spokes would get loose, requiring more tension, making the rim worse, etc.

ive had my hub motor for over 2 years with no problem, but he doesn't see this as a good enough sample size, as i weigh 12 stone instead of his 14-15stone.

Click to expand...

It's not just the weight, it's the usage. (smooth roads vs impacts) ON smooth roads the weight won't really matter much, but the worse the bump the more the weigth matters (mass x velocity).


For instance, SB Cruiser with me on it weighs something like 500lbs. The wheels on it are quite strong, I built them well. They handle most stuff fine, and the weight doesn't cause any problems by itself.

But...deep potholes with sharp edges where large chunks of pavement are completley missing are another thing entirely. I've destroyed one rim (wiht zero spoke damage) crushing the edge of the rim where the tire bead seats; it actually would've been "ok" but I bent it back, and that made it split and eventually spread across the rim further and further. The second rim this happened to is actually still working fine (as are it's spokes), since I didn't try to fix the bend, although it's bent enough to be untruable (no rim brakes so doesn't really matter that much).

Heck, I even hauled an upright piano (800lbs? more? Dunno) on a trailer built with two sets of paired ("duallie") regular 26" bicycle wheels for several miles, and they handled it fine, but I also specifically avoided all the nonsmooth surfaces that I could, and kept speed down so that any holes I did hit would have much less impact velocity / energy. (it's also been used to haul several hundred pounds of dog food, wiht just two wheels, under similar conditions)


The spokes on SB Cruiser's rear wheels are short (70-80mm? Cant' remember) and 13g-14g butted. Radially laced due to the rim size vs motor diameter. THe rims are wide 20" rims, originally from a very early Zero Motorcycle design, IIRC, one that was more built along the lines of a high power bicycle than motorcycle. and I'm using 16" x 2.5" moped/mc tires (shinko sr714) for puncutre resistance and wear life, as well as the extra cushion of the larger tire (they're much bigger than "2.5"" bicycle tires would be) at the lower pressure they use.

I could probably have used 14-15g butted just as well.

The really cheap kits can be incredibly shoddy. I know one case where the bike ran for about 2 miles, then broke most of the spokes. This was a 20" radial lace though, in 26" they tend to do better.

But for sure, you have to be vigilant, and not run a loose wheel, or bend it, and overtighten to straighten the rim. Those cheap spokes stretch a lot in the first few miles, so run a mile, check it, run a few more, check it again. Typically the cheap wheels will settle down a lot after the first 50 miles. I can't suggest strongly enough, put 50 easy street miles on it and then true the wheel before doing the bashing.

If you start breaking spokes, time to get the length, and then replace em all with better quality spokes.

I weigh 190 pounds, and with a decent rim and siapam spokes, I have done years of bashing and never broke a spoke. I did taco bend a wheel once, but that was a rider caused deal, jamming the wheel in a corner of curb. The spokes did not break, just the rim got badly bent. Those wheels were the stock wheel from E-Bikekit, or Grin. Nothing too fancy, just not the cheapest spoke you can find in china.

Breaking spokes depends more on how well you tension and maintain them than anything and a 1000W motor is nothing to worry about.

One of the latest buyers of our new 6-passenger e-pedicab decided to test its limits. He loaded it up with ten other pedicabbers and went hooning around making hard turns. After a few hours of doing this intermittently, it made noise indicating he'd broken spokes, and he stopped... and one of the rear wheels collapsed under the weight. In the process it broke almost all the remaining spokes on that side of the wheel.

Most of the affected spokes had torn the threads out of their nipples; at least one had pulled the head off the spoke nipple. One was broken near the midpoint of the spoke; one was broken near the root of the thread.

The wheels are 48 spoke proprietary units built with 14-15ga butted spokes and custom manufactured eyeleted 2.5" wide double walled rims. This is not a hub motor wheel-- it's almost the opposite, being wider than a normal bicycle hub instead of having narrower flange spacing. That makes it several times stronger and more reliable than a hub motor wheel, though there are some common principles that apply to both.

Notably, no spokes were broken at the elbow. The hub flange was slightly bent and heavily notched from overloading the spokes.



Strangely, the rim wasn't obviously bent. It's not perfectly flat when laid on a surface table, but it's not too bad. I'm going to try to rebuild the wheel with the same rim and hub, replacing all the spokes. I don't think I can fix what's wrong with the knucklehead driver, though.

My lifes story, broken your rim or broken your spokes :lol: :lol: :lol: :lol: :lol: :lol: :lol:
sheeeeeeeeeeeeesh :lol:
380'ish lbs 8)

jimmyhackers said:

my friend is on the cusp of buying a hub motor kit. he wants to create an offroad hill bashing semi-motorbike.

ive suggested he gets a cheappy 1000watt brushless rear hub motor kit on ebay like i have done, then overpower it with a better controller, like i have done.

his only concern (not one in my mind) is that the spokes and rim arent up to par.

ive had my hub motor for over 2 years with no problem, but he doesn't see this as a good enough sample size, as i weigh 12 stone instead of his 14-15stone.

if its not too much trouble can everyone please post their weight, how long their hub motor spokes and rim has lasted without breaking and what kind of riding they do on their bike please.
also if you have broken the rim or spokes can you please let me know what you did to do so.

thanks in advance
jim

Click to expand...

They key to a quality wheel build is:
Using quality components, like Sapim Spokes/Nipples
Do not go 12g as the 13/14 butted are better because it allows the wheel to flex.
Buy a good rim, double walled of course. Lace it and of course flex the rim on its axle, I do that.

The motorcycle/scooter rims are an option, a little bit heavier of an option. I would only suggest that if you are a heavy weight like me and Chalo are. Chalo dislikes motorcycle rims. Others like motorcycle rims. I have done a week on the Alex DM24, bought two with spokes. After that its motorcycle rims for me.

The funny thing is, I have the opposite of a good build. Single rim. Shortening cheap Huffy OEM spokes, and breaking just one of my forged in fire customs on initial install. (this is not a recommendation )






So I'm thinking having and keeping correct tension. Or perhaps my no-cross pattern which keeps the angle to the rim to a minimum.



Still running for over a year, but typically on paved roads and path... no torture here!

Cheap ebay 1000 watt kit with 12gauge spokes and Champion brand Chinese rim.

This is a commuter on a hardtail with front suspension. Terrain is mostly smooth but there are some severe bumps in the pavement at times.

Typical speeds 20-28 mph. Top speeds of 35 -40mph on some downhill sections.

I weigh 165-170 lbs. The bike is very rear heavy with about 30 lbs over the rear wheel not including the hub motor itself. I think bike weighs nearly 70 lbs at the rear wheel (placed on bathroom scale).

At around the 5000 mile mark I started breaking spokes. Rim holes started showing cracks though there was never any complete failure in any hole and the rim stayed true even when the spokes broke (at the elbow). Nothing was ever close to leaving me stranded, but I had the wheel re-built because this is a daily commuter and reliability is important. The rebuild of the wheel cost nearly as much as the entire ebay kit to begin with. I have about 2000 miles on the new wheel and all is good so far.

Maybe someone who already broke some spokes and know what's better for 12kg 205 hub in 16'' moped rim?
Would it be thin ones - 2.6mm or thicker - 3.2mm or 3.5mm? In one cross pattern.
Somewhere read that 2.6mm are more springy and strong enough for heavy hub, but my hub has 4.2mm spoke holes, rim has 6mm holes therefore washers are needed everywhere if I put thin spokes.