Wheel Strength

General Discussion about electric bicycles.
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OldHamster   1 mW

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Wheel Strength

Post by OldHamster » Dec 26 2014 6:51pm

I am thinking of setting a bike up with a 36v 25amphr carrier mounted battery and a rear 700c wheel with a 500w DD motor from ConHis. My current concern is whether the wheel will be capable of carrying the weight without buckling.

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Chalo   100 GW

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Re: Wheel Strength

Post by Chalo » Dec 26 2014 7:09pm

OldHamster wrote:I am thinking of setting a bike up with a 36v 25amphr carrier mounted battery and a rear 700c wheel with a 500w DD motor from ConHis. My current concern is whether the wheel will be capable of carrying the weight without buckling.
If a qualified person builds up your wheel with a decent rim and good spokes, then it will be more than capable of what you have in mind. If it's built up from absolute minimum quality parts by a Chinese teenager, then it probably won't be reliable for any duty at all.

I recommend the Sun Rhyno Lite rim if you're OK with wider tires (over 32mm). It's strong, inexpensive, easy to get, and proven.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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arkmundi   1 GW

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Re: Wheel Strength

Post by arkmundi » Dec 26 2014 7:25pm

Ditto Chalo. Its the faster speeds that will do your wheel in. Hitting a pothole at 30mph is neither fun nor at all good for your wheel. My first build, a 500 watt front hub motor from Heinzman at 36V, saw a couple of failed wheels. It was not the front wheel, interesting enough. I had that motor delivered to me laced into wheel and the guy I got it from used a good rim & spokes. Never seen any failure. Have not even had to tighten spokes. Yea, a good wheel build can be that good. It was the rear wheel that saw the damage - broken spokes, warped rims etc. So I finally got around to get an Alexrims DM24 wheel with good spokes, tubes and tires and was fine.

So when building up my second build - a MAC 10T on a Trek Shift 3 hybrid frame - I had Paul over at EM3ev put that on an Alexrims DX32 rim with Sapim spokes. He uses 13 ga spokes. Then put on a good downhill tube and a Maxxis Hookworm 2.5" tire. Its a really awesome wheel. Again, a well done wheel build with quality parts. Will last me years before I see any damage, I expect. Best. :mrgreen:

OldHamster   1 mW

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Re: Wheel Strength

Post by OldHamster » Dec 26 2014 7:34pm

Thanks for the replies guys. Any views as to the strength of the wheels used by ConHisMotors http://www.conhismotor.com/Diy_eBike.asp

MeanGene36542   10 mW

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Re: Wheel Strength

Post by MeanGene36542 » Dec 26 2014 9:55pm

Are these considered "better than average?" 700c Double Walled eZee Rim (Weinmann) (Didn't mean to hijack your thread... sorry)

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amberwolf   100 GW

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Re: Wheel Strength

Post by amberwolf » Dec 27 2014 3:35am

Got a link?
OldHamster wrote:Any views as to the strength of the wheels used by ConHisMotors
Yes: Chalo gave you one that is probably accurate enough, if roughly said.

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friendly1uk   10 MW

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Re: Wheel Strength

Post by friendly1uk » Dec 27 2014 4:32am

25ah and a motor might weigh 15kg. The kind of thing you see between riders. Or after a good steak. Or a good S.....
bmsbattery sent me broken and incorrect stuff, and won't even talk to me about it.

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voicecoils   10 MW

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Re: Wheel Strength

Post by voicecoils » Dec 27 2014 5:43am

MeanGene36542 wrote:Are these considered "better than average?" 700c Double Walled eZee Rim (Weinmann) (Didn't mean to hijack your thread... sorry)
A nice wheel can be made with Weinmann rims. I've built hubmotor wheels using the 700c X-PLORER & XP26 as well as SP17 & DM30 in 26" and DM30 in 24" and 20". You can spend more on rims with a welded joint and eyelets but a long lasting and well serving wheel can be built with any of the models I've mentioned. They make zillions of other rims but those are the ones I have direct experience with.

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dogman dan   100 GW

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Re: Wheel Strength

Post by dogman dan » Dec 27 2014 8:53am

Conhis, or any other low priced kit will not come with a great wheel build. But it could still hold up ok if you take some time to care for it. Particularly the first 100-200 miles, you need to keep adjusting the spokes as they stretch, then if you are lucky, the spokes aren't so bad and can hold up a long time. If you are unlucky, and they are spokes from a shitty batch, you are screwed.

Then it depends on how you ride. If you weigh a lot, and never manage to miss potholes, and travel 30 mph, the wheel will be taking quite a beating. If you weigh less, and ride nimbly at 20 mph, you should see a lot longer lifespan from your rim and spokes.

But at some point, you might need to relace it, or even just jump to a better kit entirely.

rider95   1 kW

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Re: Wheel Strength

Post by rider95 » Dec 27 2014 1:33pm

[quote] minimum quality parts by a Chinese teenager, then it probably won't be reliable for any duty at all.
Yep just have a good shop build a wheel

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MadRhino   100 GW

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Re: Wheel Strength

Post by MadRhino » Dec 28 2014 1:47pm

rider95 wrote:
minimum quality parts by a Chinese teenager, then it probably won't be reliable for any duty at all.
Yep just have a good shop build a wheel
Most shops, even the good ones, are not doing a good job lacing a hub motor. None of them will do it right if you feed it high power anyway. That is because they know very little about the way a lacing job should be done with a high power motor wheel, and if they would they would run into the lack of nipple washers on the market today. Can you imagine a bike shop spending 4 hours making custom nipple washers ? You will only have a good lacing job if you are willing to use a f****** heavy moped rim, if they have them of course.

Do yourself a favor and learn to do it yourself. Use a wide, top quality MTB rim. Drill it at proper spoke angle to match your motor diameter. Use quality SS spokes, long nipples, and make your own oval nipple washers with matching seat for the nipple head. Lace it plain single cross, and use (soft alu or brass) flange washers if the spoke heads or J-bend are not a good match with your motor flange thickness and holes. True it perfect and very tight. That last part you can have a bike shop to complete if you don't feel confident to do it right. If you bring them a fully built wheel and specify that you want it unusually tight, for that they don't need to worry because it has long nipples and washers in the rim as well, then most bike shops will finish it perfect. A wheel built that way can be beaten daily in mountain trails, fed 20Kw if you have the balls, and it will last reliably.
Make it fool-proof, and I will make a better fool.
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arkmundi   1 GW

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Re: Wheel Strength

Post by arkmundi » Dec 28 2014 5:20pm

MadRhino wrote:.... and make your own oval nipple washers with matching seat for the nipple head...
Can you elaborate or point me in the right direction? Thanks.

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biohazardman   100 kW

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Re: Wheel Strength

Post by biohazardman » Dec 28 2014 8:08pm

Lots of good information here nice to see it that way. I run the Weinmann 26inch pinned rims with disk brakes as well and have 10K+ at mostly 25-30MPH on them. Have some Ryhno Lites just waiting as well. Had a shop build the first wheel and after the mess I saw learned to do it myself. Most bike shops are not exposed to ebike stuff so try to build the wheel as a normal bicycle wheel. Doesn't werq that well and few will take the time to actually drill the rim to match the spoke angle. I made washers with a punch easily made by spinning a metal rod/bolt or whatever is laying around in a drill and holding a file and later sandpaper to it until it is the right shape. After that I found a nut the right size and laid the washer in the nut and punched it with the punch I made. These shaped washers, mine were round, werqed very well when I put them on the motor. My washers were brass and used on the motor but expect stainless would be good as well on the motor or in the rim. Take your time learn it and get it right and it will serve you well. I did drill my rim to match the spoke angles but have a lighter load than you so did not use the washers inside the rim no problems as yet. There are spoke washers out there already made if you google them and look through the pics you can probly find them.

http://www.endless-sphere.com/forums/vi ... =3&t=22800

http://www.sapim.be/tools/washers
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MadRhino   100 GW

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Re: Wheel Strength

Post by MadRhino » Dec 29 2014 2:17pm

arkmundi wrote:
MadRhino wrote:.... and make your own oval nipple washers with matching seat for the nipple head...
Can you elaborate or point me in the right direction? Thanks.
Well, when you try to make and fit them, you will understand at once the shape that is required.
It has to be oval to be inserted into the hole in the inside wall of the (double wall) rim. It needs to have a countersink to match the nipple head so it can rest at an angle that is matching the spoke angle. In the rim, washers can be made of any metal, but if you need washers for the spoke head to match the motor flange, those have to be small and soft so you can punch the spoke head into them.

Flange washers are not always necessary, for you may be lucky and have a perfect match. Rim washers are a must to build a strong motor wheel with a bicycle rim. Even the best MTB rims are not thick enough to stand very high spoke tension, and the nipple head will crack the rim sooner or later if the force is not spread around the nipple hole.

Motorcycle and moped rims, even some very thick single wall bicycle rims are strong enough and much easier to lace a motor in, but they are also very heavy. Performance and efficiency are greatly affected by wheel weight, mostly rim and tire since they are at the longest lever point from the axle, thus making the most resistance to acceleration and braking. There is a neat performance advantage using bicycle tires and light weight double wall MTB rims, that is well worth the trouble of building a strong light weight wheel.

If the bike frame can clear them, using wide rim and tires is also making a bicycle wheel much better, both for traction and resistance. On a wider rim, a tire contains more air volume and will require a lower PSI. The more air you have between the rim and an impact, the better the wheel can survive. The more rubber surface touching the ground, the smoother and safer the ride. The optimal ratio is a rim width that is 2/3 of the tire width, so a 2" rim with a 3" tire is a perfect combo for riding fast and hitting hard. After that, suspension tuning is your best investment to make your wheels survive extreme abuse.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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dogman dan   100 GW

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Re: Wheel Strength

Post by dogman dan » Dec 30 2014 6:30am

Great explanations of how to build the strongest possible wheel for off road use. I don't know this riders weight, but it's possible he's big enough to need that, even for street riding.

But on the other hand if he's a normal guy, say 220 pounds or less, just a decent rim intended for cargo bikes, the kind with eyelets in the spoke holes, and spokes of known good quality should be all he needs for carrying a bit of extra weight on his rear rack.

The wheel he has now should work for a time if he keeps up with his spoke tensions, but I'd suggest sourcing a strong rim and some quality spokes from a trusted vendor now would be a good idea, with the plan to relace the motor later. At the very least, have some spare spokes in hand.

Or, plan on replacing the entire motor at some time in the future from a vendor known to build a decent wheel.

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Ykick   100 GW

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Re: Wheel Strength

Post by Ykick » Dec 30 2014 7:04am

I'm sorry, but this is well worth repeating:
MadRhino wrote:Well, when you try to make and fit them, you will understand at once the shape that is required.
It has to be oval to be inserted into the hole in the inside wall of the (double wall) rim. It needs to have a countersink to match the nipple head so it can rest at an angle that is matching the spoke angle. In the rim, washers can be made of any metal, but if you need washers for the spoke head to match the motor flange, those have to be small and soft so you can punch the spoke head into them.

Flange washers are not always necessary, for you may be lucky and have a perfect match. Rim washers are a must to build a strong motor wheel with a bicycle rim. Even the best MTB rims are not thick enough to stand very high spoke tension, and the nipple head will crack the rim sooner or later if the force is not spread around the nipple hole.

Motorcycle and moped rims, even some very thick single wall bicycle rims are strong enough and much easier to lace a motor in, but they are also very heavy. Performance and efficiency are greatly affected by wheel weight, mostly rim and tire since they are at the longest lever point from the axle, thus making the most resistance to acceleration and braking. There is a neat performance advantage using bicycle tires and light weight double wall MTB rims, that is well worth the trouble of building a strong light weight wheel.

If the bike frame can clear them, using wide rim and tires is also making a bicycle wheel much better, both for traction and resistance. On a wider rim, a tire contains more air volume and will require a lower PSI. The more air you have between the rim and an impact, the better the wheel can survive. The more rubber surface touching the ground, the smoother and safer the ride. The optimal ratio is a rim width that is 2/3 of the tire width, so a 2" rim with a 3" tire is a perfect combo for riding fast and hitting hard. After that, suspension tuning is your best investment to make your wheels survive extreme abuse.
Posts like this which help make this site such an invaluable resource, IMO. Thanks MR...
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arkmundi   1 GW

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Re: Wheel Strength

Post by arkmundi » Dec 30 2014 9:13am

MadRhino wrote:Well, when you try to make and fit them, you will understand at once ....
Thanks for the excellent explanation. Yea, do understand better and will be attempting a quality wheel build for the first time. FYI, its for the MXUS 3000 watt hub on an Alexrims DX32, Maxxis Hookworm 2.5" tires. Best!

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MadRhino   100 GW

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Re: Wheel Strength

Post by MadRhino » Dec 30 2014 1:07pm

arkmundi wrote:... FYI, its for the MXUS 3000 watt hub on an Alexrims DX32, Maxxis Hookworm 2.5" tires. Best!
The space between the inside and outside walls of a DX32 is very thin. Your rim washers will need to be thin with a deep countersink to fit the nipple in there. Good thing to know first, when I built the first one I couldn't fit the washers that I had prepared for the job. Other than that, this rim is a good choice for its width, lateral stiffness and light weight.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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friendly1uk   10 MW

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Re: Wheel Strength

Post by friendly1uk » Dec 30 2014 1:20pm

I don't think it's worth building wheels with anything but top quality spokes. Even if the alternative was free. The cost of a breakdown is too high. It takes me hours to do a wheel, and that's after getting the bike home. Quality spokes are cheap insurance.

I like these http://www.sapim.be/spokes/butted/strong
If I were using a short spoke in a m/c rim I would use 12g. A 500w DD in a 700 would likely be fine on good 13g.
bmsbattery sent me broken and incorrect stuff, and won't even talk to me about it.

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