LightningRods mid drive kit

[jimnasium]

It would make the part more labor intensive and more expensive, but it would be nice to have welded captive nuts on the inside of the adjuster bracket for the side bolts to thread into. Fiddling with loose nuts up inside of the lower sheets would be extremely frustrating.

Mike, I was thinking about how to simplify the design so that it was more rigid AND less "fiddly". What if the lower sheet pivoted around a riveted axle, rather than slid. In the illustration, the pink circle would be a riveted axis of rotation. The motor would rotate around this and your single pusher bolt would provide the tension for the 2ndary chain. The advantage of this design (might) be that it would be easier to assemble and would not skew to the side due to the force of the chain. NOTE: the actual location of the rivet and the pusher bolt are not meant to be accurate in the picture. In fact, you'd probably want 2 pusher bolts, one above and one below the axis of rotation.

On the upper sheet, you could employ a similar idea. Pin one of the 2 jackshaft bolts in place so as to lock it perpendicular to the sheets. The second one would slide in an arc to provide tensioning. Also, since the size of the belt is known in advance, the range of adjustment does not need to be so great. Only enough to get the belt on and off.

Just an (untested) idea! It's easy for me to be "armchair designer"... I don't mean to imply that any of these ideas are better than what you've accomplished with actual metal.

 

[jimnasium]

Looks like your doing a great job. Keep up the great work !!

Do these things come in a tiny 250 w ? (Legality issues)

I can make a "250 watt" sticker for you if you like. :wink:

That's easy. You just power this with a 48V, 5.2A battery. You could also use a Cycle Analyst to limit the power.

 

[sparkz]

Do these things come in a tiny 250 w ? (Legality issues)

Just put this on the bike...

 

[emaayan]

Looks like your doing a great job. Keep up the great work !!

Do these things come in a tiny 250 w ? (Legality issues)

the kit is built to withstand loads of 1500 watts, maybe even 2000, if you REALLY want a 250w mid drive, that's a major overkill.

 

[LightningRods]

God bless the great state of Oregon for allowing us 1,000 watts on the road. But the law makers must be a bit fuzzy on e-bike physics because they also set the speed limit at 20 mph. So we get four times the power limit the EU gets and then can't go any faster on the flats than we could with 250 watts.

 

[emaayan]

God bless the great state of Oregon for allowing us 1,000 watts on the road. But the law makers must be a bit fuzzy on e-bike physics because they also set the speed limit at 20 mph. So we get four times the power limit the EU gets and then can't go any faster on the flats than we could with 250 watts.

your lawmakers are fuzzy, period, i went dizzy after reading http://www.electricbike.com/electric-bike-law/ , but hey count your blessings, that you actually live in a country that doesn't make you fight customs for importing kits, from what i understand, if you try to import ANY kit, as a private consumer to israel, even if you do declare it as 250 watts, it will get sent to regulatory checks, which means no kit basically.

on another note, can anyone post a a small video showing the problem with loose screw on the down tube? it's little hard for me to figure out,i think it get the same problem ecospeed kit but plates there are very thick, so although i do see some movement it's very small.

 

[stonezone]

Has anyone recieved/begun assembly of the 'big block' kits? Looks like mine is in production... I was just wondering if there's anything I'll need to be aware of besides what's being discussed on here already.

Once I get mine i'll keep a build log and post it as time permits.

Thanks, and keep up the good work, this community is unmatched in my opinion.

SZ

 

[Mammalian04]

Has anyone recieved/begun assembly of the 'big block' kits? Looks like mine is in production... I was just wondering if there's anything I'll need to be aware of besides what's being discussed on here already.

Once I get mine i'll keep a build log and post it as time permits.

Thanks, and keep up the good work, this community is unmatched in my opinion.

SZ

Post up when you start your thread. I am a big block and will be watching your build intently!

 

[spinningmagnets]

Lots of BB chat and builds here...

"Big Block GNG alternative motor"
http://endless-sphere.com/forums/viewtopic.php?f=28&t=57483&start=150

 

[LightningRods]

Hey Big Blockers- I'm past the motor shaft crisis, I just beat 10 sets of small block jackshafts and housings out of my machinist buddy Steve, and I'm now sending him drawings of the big block jackshaft and housing. They're about 30mm wider than the small block set. I hope to be getting big block parts for the first builds next week.

Based on feedback about a couple of the lower brackets I'm going to revise the big block lower adjusters before releasing them. They will have two adjuster bolts so that you can force the motor to be level and stay level, and also four welded captive nuts with four grade 8 bolts holding the BB and motor slides together. I am all about not futzing around with a problem.

I'm still ordering big blocks one at a time off of TaoBao but I'm ready to step up and get a pallet of 100 from the factory. It takes FOREVER to get the right motor off of TaoBao.

 

[sparkz]

Based on feedback about a couple of the lower brackets I'm going to revise the big block lower adjusters before releasing them. They will have two adjuster bolts so that you can force the motor to be level and stay level, and also four welded captive nuts with four grade 8 bolts holding the BB and motor slides together. I am all about not futzing around with a problem.

Yes! The Big Hammer! Shock and awe! The only way to deal with a problem. I've moved up the queue into the teens, and can almost smell the machine oil. I am building a small form to cast a custom-formed urethane backing for the motor. If I have any success, I'll post pics of how I did it. Failures will not be advertised.

 

[Mammalian04]

Happy to see these changes being oncorporated. BTW, I have my raptor frames now in case you need any addition photos for the mount.

 

[sparkz]

LR - I sent you info and specs on my bike awhile back (PMs). If you need photos, just let me know.

 

[emaayan]

L-R, have managed to install your kit, and get any insights ?

 

[BRK]

Hey guys, I just rec'd a notification of shipment on my L-R kit! So exciting! I'll take a look at this racking motion on the right side after I get everything in and the install going. I am hoping that with my steel framed Surly, I'll be able to come up with something to take up the torque.

 

[LightningRods]

BRK- I've used the separate side plate bolts rather than long bolts that go all the way through on your kit. It should clamp the side plates better. Let me know how it works out for you. Thanks for your service in Oman!

 

[Dani]

A design question: Why did you go with HTD 5M with 25mm instead of, say, 8M with 20mm?

 

[LightningRods]

Good question. Initially I was thinking that I might have to utilize one of the 5mm pitch HTD large pulleys that were available. The critical problem was the driver pulley. As this evolved I created my own GT 5mm large pulley.

When you take space into consideration I think that the benefits of 8mm pitch belts are exaggerated. Each tooth has more power capacity but you end up with fewer teeth in the same diameter pulley. Matt uses 8mm in his excellent DiVinci drives but typically goes for less reduction in each stage. I wanted at least 5:1 which there was just barely room for even with 5mm.

 

[Dani]

Thanks for the insight. I thought 8M with 20mm should do the job as good as 5M with 25mm. I see now that the tooth count on the driver is a problem, indeed.
90T/18T = 5, so you have a reduction of 1:5. 18T (5M) = 28.65 pitch circle.
Minimal suggested tooth count on 8M is 22 with a pitch circle of 56. To get the same ratio I should split the tooth count to 11. My research tells me this is very little, but it's 8M nonetheless. As I understood the problem is not the amount of tooths that are in touch with the pulley. The load is always on the last few (two? three?) tooths, and we surely will have 3 teeth in touch. If the big and small pulley are close to each other this will be a problem, but i can easily get 6 tooths to grip with another pulley tensioner.

I think it could work without a tensioner. ~30% of 11 teeth = 3,3, so I will always split the load on to at least 2 tooths, 3 most of the time.

Argh, I Can't stop thinking that a gearbox from scratch would work so much better in terms of space, cost and coolness.

PS: Sorry for offtopic

 

[Mammalian04]

Fooffff!!!! All over my head. Thank god LR is figuring this out for me.

 

[emaayan]

a gearbox? will that hold under a load?

 

[Dani]

a gearbox? will that hold under a load?

Oh you! A gearbox is designed to hold under load :lol:

 

[emaayan]

i'm talking about major load, for example i was told the a planetary gear, will no be able to withstand big abuse.

 

[LightningRods]

As I understood the problem is not the amount of tooths that are in touch with the pulley. The load is always on the last few (two? three?) tooths, and we surely will have 3 teeth in touch.

I don't think that this is accurate. The load is spread evenly among the teeth engaged. The spec that I have read repeatedly is 6 teeth engaged minimum.

Reducing the number of teeth engaged pretty evenly offsets the advantage of using M8 pulleys and belt. Using an idler to backbend the belt is avoiding the question of whether M8 is better in this limited space. For the same tooth count an 8mm pulley is going to be 60% larger. When space is tight that's a problem.

I can't argue that M8 has more grip. But I think you either need more room or have to settle for less reduction in order to see that advantage.

 

[recumpence]

I use 5mm pitch on my Davinci drive. I do use 8mm on the second stage of my high torque two stage drive. 8mm handles far more power. But you cannot get as deep a ratio with 8mm.