Will this combination work?

[Chalo]

Don't use more than one cross on a hub motor. Your spokes will break at the threaded end if you do.

What about two cross on a small geared hub motor (113mm spoke hole diameter) in a 700c (sun cr-18) rim? Is that a practical combination? Kinda late to be asking since I already built it and it looks ok but this is outside my experience so I don't really know.

That's "maybe, maybe not", depending on the specifics of the nipple diameter, rim hole diameter, flange lateral spacing, etc.

You can tell whether you are likely to have problems by looking at the fully assembled and tensioned wheel. if the nipples sit in the rim at a different angle than the spokes emerging from them, then stress will concentrate at that bend and some spokes will eventually break there. If the nipps are aligned with the spokes, then you have no problem.

The last wheel I had with that problem was a 7-speed gearhub of about 90mm pattern diameter that I laced cross-four on a 700c rim. It was the companion to my X5305 hub motor which was laced cross-one on the same rim, which did not have the same issue with occasional spoke breakage.

 

[-dg]

You can tell whether you are likely to have problems by looking at the fully assembled and tensioned wheel. if the nipples sit in the rim at a different angle than the spokes emerging from them, then stress will concentrate at that bend and some spokes will eventually break there. If the nipps are aligned with the spokes, then you have no problem.

Hmmm, they are almost straight, but a few are just perceptibly not. I'll keep an eye on it.

Any suggestions for a 26" rim for a BPM in a rear wheel for a large rider on fairly bad paved roads? I was thinking Sapim Force or similar 13/15/14 butted spokes but have not chosen a rim yet.

 

[Chalo]

Any suggestions for a 26" rim for a BPM in a rear wheel for a large rider on fairly bad paved roads? I was thinking Sapim Force or similar 13/15/14 butted spokes but have not chosen a rim yet.

Butted spokes are the ticket, since their increased elasticity helps the rim bear loads across a larger area. There's no reason to spend extra for 13ga elbows unless they fit the hub holes a lot better than 14ga. In my casual observation, most of the inexpensive Chinese made hub motors have huge holes for which even 13ga spokes should probably be fitted with washers under the heads.

In the real world, DT Alpine III 13/15/14ga spokes break more often than DT Competition 14/15/14ga. I don't know why that would be, but it certainly isn't because the folks at DT don't understand what they're doing. Perhaps the thicker elbows are harder to stress-relieve.

For my money, I'd use the $0.40 Sapim double butted spokes from Danscomp.com. That's about two-thirds of my wholesale distributor's price on DT Competitions, and they are just as good. Grab a handful of extras to ensure that you won't need them.

 

[-dg]

Any suggestions for a 26" rim for a BPM in a rear wheel for a large rider on fairly bad paved roads? I was thinking Sapim Force or similar 13/15/14 butted spokes but have not chosen a rim yet.

In my casual observation, most of the inexpensive Chinese made hub motors have huge holes for which even 13ga spokes should probably be fitted with washers under the heads.

In the real world, DT Alpine III 13/15/14ga spokes break more often than DT Competition 14/15/14ga. I don't know why that would be, but it certainly isn't because the folks at DT don't understand what they're doing. Perhaps the thicker elbows are harder to stress-relieve.

For my money, I'd use the $0.40 Sapim double butted spokes from Danscomp.com. That's about two-thirds of my wholesale distributor's price on DT Competitions, and they are just as good. Grab a handful of extras to ensure that you won't need them.

On normal hubs I always use 14/15 DB spokes and lately I get them from Danscomp. I don't know how they do it, but I'm glad they do.

I'm surprised that the 13/15/14 spokes break more, just goes to show that on bikes bigger is not always better or something. I like your theory about stress relieving as they would take more force to get to the yield point. Maybe amateur wheel builders like myself are just too timid to apply enough force. I'll stop using them and put the money into washers instead for hub motor builds. Any suggestions on a source and kind of washer?

But, my original question was, I'm looking for a rim recommendation for 26" wheel with a 2.1 tire for a rear gear motor and a gross weight around 330 lbs on badly maintained paved roads. No plans to exceed 25 mph except under the influence of gravity. I;m pretty easy on equipment and rarely break stuff, partly because I like stuff that is known to work. I have mostly built road bike wheels so don't have a default rim for 26". Any suggestions you care to make would be helpful.

 

[d8veh]

I use 2 cross on all my wheels with BMSBattery rims and spokes. Never had a problem.

 

[Chalo]

But, my original question was, I'm looking for a rim recommendation for 26" wheel with a 2.1 tire for a rear gear motor and a gross weight around 330 lbs on badly maintained paved roads.

First choice for me (when cost matters) is Alex DM-24. Best rim for the money, ever. It looks like it may be going away soon, but at the moment I can still get 36 hole versions in 20", 24", and 26".

If you can find a new old stock Sun Mammoth or BFR, that's also a great rim for the money, very strong and with the best rim braking surface I have ever seen (tall and concave, for perfect setup with pads that swing up, down, or straight in).

Weinmann DM30 is a clone of the Alex DM24, a little cheaper and without eyelets. Also a good choice when low cost is a priority. It comes in 14ga and 12ga drillings, and might even be beefy enough to withstand tension that would keep 12ga spokes taut. Maybe. (That's like 180kgf per spoke.)

Velocity Psycho is even stronger than all of the above, a little heavier, a lot more expensive, and made with the usual impeccable Velocity quality control.

Velocity Cliffhanger is unbeatable for strength-to-weight if its price is acceptable. All the Velocity rims with that shape (Aerohead, A23, Dyad, Aeroheat) have unbelievable strength and durability for their weight, and the Cliffhanger is the big daddy of them all. So if weight efficiency is a priority, that's a good choice.

I'm now trying out a Velocity rim that I have very little previous experience with, but the results are promising. It's called P35, and it's not suitable for a rim brake of any kind-- on a hub motor, discs or band brakes would be your only choices. But it's 35mm wide, so it opens up and stabilizes the tire. (That makes tires work better at cushy low pressures.) And it's quite stiff despite being the lightest rim I have suggested yet. If you know you are going to use discs, and Velocity prices don't turn you off, I can recommend the P35 based on building it and riding it so far.

For overkill strength and lateral rigidity at a reasonable price, there is the Nimbus mountain unicycle rim. Nothing about your application seems to require such a huge rim, but it's a good value and not too wide to use with a 2" tire.

 

[-dg]

First choice for me (when cost matters) is Alex DM-24. Best rim for the money, ever. It looks like it may be going away soon, but at the moment I can still get 36 hole versions in 20", 24", and 26".

If you can find a new old stock Sun Mammoth or BFR, that's also a great rim for the money, very strong and with the best rim braking surface I have ever seen (tall and concave, for perfect setup with pads that swing up, down, or straight in).

Velocity Cliffhanger is unbeatable for strength-to-weight if its price is acceptable. All the Velocity rims with that shape (Aerohead, A23, Dyad, Aeroheat) have unbelievable strength and durability for their weight, and the Cliffhanger is the big daddy of them all. So if weight efficiency is a priority, that's a good choice.

Thanks for this. I have built several successful sets of wheels, but they have all been 700c for tires between 25 and 35 mm so I'm not as familiar with the 26" parts.

The bike is an early 90s Trek 950, picked up on CL for $80 (around here old steel road bikes are "vintage", but old steel mountain bikes are "obsolete", all it needed was a chain and a some scrubbing) so I'm going for cost effective over weight effective, but I still want it to turn out nice. I got it to save me from any temptation to electrify my "Precious" (1984 Specialized Sequoia).

The Cliffhangers look great, the Psychos a bit like overkill. But for this bike I'm thinking maybe DM-24s. No love for the Sun Rhyno Lite? Or is it to light for this application?

 

[Chalo]

No love for the Sun Rhyno Lite? Or is it to light for this application?

I've used Rhyno Lites for many years, since back when they were all made in the USA. (I even have Sun Rhynos, not lite, on one of my bikes.) It's a good rim and cost-effective too. It only has the misfortune of being weaker than something like the Cliffhanger at a similar weight, and weaker than something like the DM24 at a similar price, and narrower than either one. Lately, Sun rims aren't quite as flat and round as I like either (though they are usually better than Weinmann).

Sun Rhyno Lite used to be the only decent MTB rim available in 700c (and it is still a very good choice in that regard), but the market is catching up somewhat.

I'm glad that the market for bicycle rims has changed enough in the last 20 years that this rim which seemed huge when it appeared now seems kind of modest and unremarkable.

 

[-dg]

Sun Rhyno Lite used to be the only decent MTB rim available in 700c (and it is still a very good choice in that regard), but the market is catching up somewhat.

I'm glad that the market for bicycle rims has changed enough in the last 20 years that this rim which seemed huge when it appeared now seems kind of modest and unremarkable.

I'll try the DM-24 if I can get one 36h in silver. Thanks.

Yeah, this bike has pretty skinny rims, not much wider than a road rim. I''ll probably just keep the front as is unless it's a problem. I''m thinking 2.0 Ribmo at the moment on the rear and my last NOS 1.9 Avocet slick on the front until it wears out.

As for progress, I"d be willing to accept that more easily if I could still get MA-2s.

 

[friendly1uk]

Which spokes are correct, the near or the far?

I think the trailing spokes should sit outside the leading spokes. So as I pull off, The trailing spoke is under tension, and the leading goes slack but can't lean out of the wheel and contact my derailleur.
I read Sheldons bit on it, but it didn't quite read right to me. Looking at examples, 80% have the trailing spoke on the inside, which I'm finding counter intuitive.

I think the back one's are correct, while most examples follow the example set by the front one's. This wheel of course does it both ways round.



I'm actually putting both leading and trailing in from the same side of the flange on my rear wheel. The idea being to offset the rear rim a few mm in the right direction. So, my drive side flange will have the spoke heads on the outside of the hub, while non drive side heads are on the inside of there flange. It's not going to fall over is it? lol

 

[Chalo]

I lace trailing spokes on the outside for conventional wheels, but that's to make them less likely to jam cords or foreign objects in towards the hub (which is probably only an issue on the sprocket side of a normal diameter rear hub). I don't think it matters structurally or dynamically as long as your spokes stay tight, and using thin spokes is a way to ensure that they do.

For hub motors with cross-1 or radial spokes, I lace them all outside the flange for a bit more bracing angle. Hub motors usually have very narrowly spaced flanges, and widening the bracing angle helps wheel stiffness. I lace the trailing spokes on top, because that's my habit as noted above.

 

[friendly1uk]

Thanks for another quality post Chalo. Helpful as always

I could thread all 36 with the elbows pointing inwards. It's quite narrow as you say. My drive spokes are a mm longer, and it shouldn't really make much difference. I just fancied the wheel being across a little before the spoke setting really gets involved. Just the act of leaning them against the flange is going to be an improvement though, so yeah.. Outside it is then. Thank you

Edit: Now.. Should I put the job off a little while longer, to get some reflective tape on the rim, so the spokes come through it. Hole punch would sort that nicely. Decisions decisions... I think it would be good, but time is pressing on. Looks like 5mm tape each side is on the cards at some later date. Be a bugger if I taped it nice, then the weather just lifted it.

 

[friendly1uk]

Tomorrow I will run the motor up for the first time. It's been a while, but I got there in the end. My car filled the cylinders with water, so I didn't have much choice but to rush the job, but it has not suffered badly.

I'm just a little concerned it might all smoke. I have a bafang cst and a ku65 from bmsbattery. Both have matching wire colours, but the plugs are not fitted, giving me the option to move some around. No instructions. Do I blindly match the colours? My experience with bms battery leads me to want to check everything. I would hate them to be behind even more smoke signals. Do I trust them, Or is there a way to actually test what is what? I was thinking I could trust them, but start at low throttle, unloaded. I have a 20 amp fuse in place. I could fit a lower one.

I don't really want to be opening the motor up unless I have to.


What is the usual approach? I thought worst case would be incorrect rotation, but some peeps have reported a functioning bike for 20 mins before smoke due to incorrect wire matching.

 

[chas58]

+1 for the win. I should have just taken d8veh's advice from the beginning.

After months of study, analysis, experimentation, and buying 3 motors (hey, I like these things and have too many bikes anyway) I ended up with what this post described as my favorite motor for a mountain bike (but have a 10ah LiFePO4 battery).

It actually has a no load speed of 28mph (fully charged 36v battery at over 40 volts). Loaded speed of the motor is 20mph, but the motor is still putting out full power at 24mph. So with good 250watts of my pedal + the motor, I'm cruising at 23-24mph, getting a good boost from the motor, and still getting a good workout. This motor is too small and fast to use on any serious hills (simulator says overheating is possible at full throttle below 12mph). Its a nice motor for true pedal assist (as you really have to pedal to help the motor, but it does give me a nice boost).

Yeah, I investigated those BMS bottle batteries. They are 1C. So, an 8ah battery isn't going to put out much more than 8 amps.

Unfortunately, there's flaws in you plan.
You can't use the 328rpm 24v Q100 at 36v in a 26" wheel. It'll try and spin too fast and be hopelessly inefficient if it doesn't burn out first. The Q100 has enough power to sustain 20 to 22mph depending on your weight, so about 25mph would be a good no load speed target.
The 24v 201 rpm one is the one you want because it has a no-load speed of about 24mph at 36v.

You need about 18 amps to get the best out of it. They can't take the 22 amps that the KU93 gives, so best is to use a 15 amp controller and solder the shunt to increase it to 18 amps. The one you want is the KU65 because it has three levels of pedal assist. Th KU63 has one, which is maximum. Make sure that it gets plenty of air flow because it'll get warm/hot

I guess you're looking at the 8aH bottle battery. Unfortunately it struggles at 15amps, so you need something more powerful for 18 amps. The 10.4 aH one would be better if it fits. Don''t forget that you need room to lift the top end of the battery out of its holder and space is very tight in the top corner of the triangle. A 12 or 15aH battery would be better for 18 amps

You won't be able to add anything to the top speed by pedalling. The motor power drops right of as you get past its top speed, and unless you're an Olympic cyclist, you won't be able to pedal a bike past 22mph on your own.

To summarise:
24v 201 rpm Q100 kit with LED display.
Ideally 12aH or more 36v battery.
Additional KU65 36v controller (maybe they'll swap the 24v one if you ask)
2 hidden wire brake sensors if you have cable brakes
Pair of torque arms (only need to fit one)

 

[chas58]

friendly1, how is that build coming? Any smokin?

 

[friendly1uk]

Hello Chas. I got it together and put some pics in the photo section. Here's the link: http://endless-sphere.com/forums/viewtopic.php?f=6&t=51064
I have not talked about performance yet, because I'm yet to get any solid benchmarks. Light pedaling through roadside traps I see 24mph. If I pedal fast I see 26-27mph and on a slight downhill I saw 29mph. However I turned the motor off and still did 29. I think it helps to about 25mph. I would of liked it to be faster, but it's hill climbing is probably the next thing to address. I'm going to mod the controller from 15 amps towards 20. I have no fear of it burning having done long climbs and felt it. That was why I over sized it. To future proof it a little. Plus the bigger case has more leverage than a mini motor, so I guess more torque, all else being equal.
I seem to average about 15mph. A week ago I sat at a desk, and walked as far as the car. So this is not bad. I can't turn the pedals quick enough though, so my crank is going from 48 to 52 this weekend and I may swap my 12 tooth rear to an 11 tooth. It's a separate cog on my cassette. I spent a lot on a cts rather than using the more popular bpm to keep this option open. If I were to build this exact bike again, I would go bpm and get the 11 tooth gear set from canada. I just didn't know what I wanted till now. I think just a 52 tooth front would be fine, but ordered a 3 sprocket crank anyway.
To cover 7.5 miles I'm using about 4Ah there, 3.5Ah back by a longer route, perhaps 8 miles.

I got my second top tube pannier bag delivered today. It is to hold some hard-packs for range improvement. 160mm wide this one said(not 150mm like the last one)and still my 139mm packs don't fit in it. One more to try... the 170mm wide one. Surely 139mm will fit in a 170mm wide bag. Although the 150mm bag is bigger than the 160mm one. The 170mm bag is likely smaller still....

At first I had an odd noise, like a wop wop wop at wheel rotation speed. Only under acceleration. Perhaps one phase having more grunt than the others. Could be windings or controller, or even my wiring. No.. can't be that. However I'm ignoring it or it has gone away. I'm not sure. I didn't open it up before use as I didn't want to get involved with there quality control. Now I know where I stand, I probably will. I am an electrician and want to shorten the cable at least. So the motor plugs to the bike loom right where it should. Not half way along my rear triangle after a number of fixings that all need removing when the wheel is removed. My photo thread explains my need better.

I'm sure you can pass one of them motors along to someone. It would be better to buy a tested motor from you than run the risk of buying from many suppliers. BMSbattery won't even talk to me now they have posted it. Mainly because of there catalogue of errors. I'm sure many would rather buy something briefly used than run the risk. I have zero warranty.

When I get some better numbers I will post them. Whenever I see a speed trap I just can't help gunning it lol

 

[friendly1uk]

Put a 52/42/32 crank on. The kind that all the sprockets can be separated. The inner sprockets mounting points wouldn't clear the pedalec magnet disc. The disc being about 3mm too wide. So I put the disc on one side of my BB and my drill on the other to spin it. Then held a file to the spinning magnet disc. It trimmed it down nicely.

 

[dnmun]

Tomorrow I will run the motor up for the first time. It's been a while, but I got there in the end. My car filled the cylinders with water, so I didn't have much choice but to rush the job, but it has not suffered badly.

I'm just a little concerned it might all smoke. I have a bafang cst and a ku65 from bmsbattery. Both have matching wire colours, but the plugs are not fitted, giving me the option to move some around. No instructions. Do I blindly match the colours? My experience with bms battery leads me to want to check everything. I would hate them to be behind even more smoke signals. Do I trust them, Or is there a way to actually test what is what? I was thinking I could trust them, but start at low throttle, unloaded. I have a 20 amp fuse in place. I could fit a lower one.

I don't really want to be opening the motor up unless I have to.


What is the usual approach? I thought worst case would be incorrect rotation, but some peeps have reported a functioning bike for 20 mins before smoke due to incorrect wire matching.

your car's motor has water in the cylinders? did you remove the radiator cap and the spark plugs and crank it over to blow the water out of the cylinders yet? if you leave the water inside the cylinders the motor will be ruined. you have to blow the water out yesterday and get the head off so it can dry out.

 

[friendly1uk]

I know pal. I got out what I could. Couldn't get round to fixing it though. It is over 2 weeks now. I knew then that another engine was on the cards. I may just scrap it, I'm due for a change. It's a turbocharged Miata, so worth more in bits anyway.

 

[dnmun]

you don't have to fix it now, but dry out the sleeves so you don't have rust. if it is warm and dry there where you are then you could leave the plugs out after you blew out all the water that you could by just turning it over and squishing it out the exhaust or through the spark plug holes.

when the water is mostly gone you can spray some oil down the spark plug hole and turn it over to coat the sleeves. i just had the head gasket blow on my honda and rebuilt the head, 1 new valve+resurfacing for $182 and $30 for a head gasket kit some guy had to dump on ebay.

car is in the best shape since i bot it, even replaced the oxygen sensor with an OEM denso sensor i found on ebay for $20, and did not strip the head bolts either. $89 new ebay distributor, fixing A/C is next!

 

[friendly1uk]

I was going to do my AC, but my wallet would of suffered from weight loss. So I took the AC off, and the car benefited from weight loss instead

I took the plugs out and span it over to get most out. It's been about 15c here though so it won't be dry. It took me a week to think about oil. I thought I should get round to it at some point sooner. It might actually be the inlet manifold gasket that failed and let the water in. It went wrong when I came to a stop. I got the inlet off yesterday and it is very possible. A water way is just 15mm from that particular inlet runner. I could of fixed that same day. Oops. No liners too, it's a solid block. A new lump is $350US but I just can't be bothered. When it stops raining next week I will put the inlet back on and see if that sorts it. Miata head gaskets just don't blow. Even 600bhp monsters use the stock gasket. I'm going to be a bit miffed if I have let it rust away because of an inlet manifold gasket. Then perhaps move house. My last 3 houses have had garages my car couldn't get in, and it is only small. This garage is to narrow by far. I never saw that coming....

 

[friendly1uk]

I have been waiting for this.... It's broke. I had a couple of stutters in the rain which cleared. The led display is running hot though and draining the battery at quite a rate. The bike works still, but it took an Ah over night.

 

[friendly1uk]

Well I have felt the display get warm once since, but it seems ok.

I'm actually back with a little 'off topic'
I got the cars head back on, and inlet side all complete. Just the exhaust side too go. Quick worker aren't I lol The weather turned cold and I snapped my chain when an idle gear in the rear derailleur moved to much. It kinda bought it all home to me. I drive a cabriolet and just missed the whole summer, but it's winter when cars count. I'm looking for something electric now.