A-Lines Abound: Electric drive implosion

[Caliban]

The "extra valve stem hole" is probably for a tyre security bolt, stops the tyre slipping around the rim.

[kfong]

I'm currently running a Stan's tubless on my BMC setup. Only the front at the moment. I not sure I'm sold on the idea. I used clear duct tape for the inner seal. There was a youtube video on it. It looked cleaner than the getto tube method. It's been holding up so far. The tire stem is the part that gave me the most trouble. You need some high pressure to get the intial seal as well. The problem I see if if I have a blowout in the woods, I better be carrying a spare inner tube. Kinda defeats not having a tube to begin with. I won't be able to do this with the rear so I'm running a thick dh tube and wheel liner to prevent flats in the back. I rearly have flats in the front and I do like the lighter feel and response of the Stan's front tire.

[MattyCiii]

The "extra valve stem hole" is probably for a tyre security bolt, stops the tyre slipping around the rim.

Thanks Caliban, appreciate the info.

[MattyCiii]

I'm currently running a Stan's tubless on my BMC setup. Only the front at the moment. I not sure I'm sold on the idea. I used clear duct tape for the inner seal. There was a youtube video on it. It looked cleaner than the getto tube method. It's been holding up so far. The tire stem is the part that gave me the most trouble. You need some high pressure to get the initial seal as well...

Thanks Kfong, I guess my concern is having to put more sealing liquid into the wheel periodically (I read somewhere you have to do that). Is that your experience as well?

Otherwise I'm on board. Running a tubeless motorcycle tire, all I need to do is ensure those 36 spoke holes are sealed up nicely, the rest should be fine.

Also, I just read your Motobecane build over the last few days, awesome build and a story well told. I'll be in touch with you about buying a Smart Switch and some of those balance tap boards - hopefully you still have some - I'll contact you separately once I figure out how many of each I need. Ingenious stuff!

[kfong]

The Motobecane is my favorite. I ride it as much as I can in the trails. Just started using the Stan's stuff this season. I've read it dries out in 6 months and you have to add more.

Not to worry, I still have all the boards in stock. I've been using them on all my new builds. They have been very reliable.

[MattyCiii]

I've decided to go tubeless on the front wheel.

With a legitimate tubeless tire and a good solid motorcycle rim, all I really need to make the whole thing tubeless is to seal the 36 spoke holes.

Rather than go with the "ghetto tubeless" approach, I'm going to follow the instructions posted here: http://www.intruderalert.com/cafe/index ... cID=132731

I've got an appropriately sized stream and GE Silicone II Aluminum and Metal formulation on the way. The stem, plus a roll of rim tape, are from Stan's Tubeless. Hopefully this works correctly on the first try, but if not I'm hoping I can just dump some Stan's Tubeless fluid down the stem and seal any leaks.

Form this I hope to gain the advantages of tubeless operation, plus maybe an easier install. The shop that installed my rear tire went through 4 tubes during the install, which does not surprise me considering how tight that tubeless tire fits on the rim.

[fractal]

hey matt, what are the advantages of tubeless tires?

[sn0wchyld]

hey matt, what are the advantages of tubeless tires?

they're usually lighter weight (no inner tube) and as close to puncture proof as you can get. basically they have a liquid in 'em that seals punchtures almost instantly. ive seen vids of a guy riding over a bead of nails, and he barely looses any air at all from his tyres.

[MattyCiii]

hey matt, what are the advantages of tubeless tires?

I've seen some advantages quoted: slower loss of pressure when the tire is breeched, possibly lower weight (no tube), and less rolling friction.

Advantage specifically in this case: I bought a slick, relatively narrow (3") wide tire for a 21" rim. This specific product is tubeless by design. This is not a case of someone forcing a standard tire to be tubeless - this is me using a tubeless tire as intended - without a tube. Chatting with my installer - the local motorcycle shop - they went through 3 tubes to get the rear wheel installed. Meaning - I tried to use a tube in a tire built to be tubeless, and that was a problem.

What I hope to achieve is a tire with a bit less weight and rolling resistance, and perhaps also make the install easier for my local shop. I suppose also to satisfy curiosity...

[kfong]

I've been putting some serious trail miles on my front tubeless, it definitly feels lighter and more responsive. It has a nice hollow sound to it. No pinch flats is one of the main advantages. Seems like half of my flats are due to this. The duct tape is holding up fine, not sure I would use silicone, seems too much unnecessary weight. Only problem spot is the cut valve from an inner tube. Mine is holding air pretty good so far. Still too afraid to use it in the rear, no way to fix it in the woods. I have to carry a spare inner tube with me now for the front in case I loose pressure somehow. I won't use slime anymore since the stuff makes it impossible to patch if I get a leak. You just end up with a gooey mess and a long walk out of the woods. Both tires did fine today, 30 miles of pure trail riding, hitting rocks, stumps and roots. The rear has thick dh tubes and a plastic liner.

[MattyCiii]

I have to carry a spare inner tube with me now for the front in case I loose pressure somehow.

Thanks for all the info Kfong... especially that quote above.

This whole bike is my rather expensive, learn-by-doing, no compromises machine. The 16" moto wheels I started out with in 406mm x 47mm Recumpense rims work really well. With them I could fix a flat or change a tube by hand alone, and have bicycle tire levers in my tool bag if I want to make the job even easier. The m'cycle tires for these were meant to ride with tubes. This setup had everything in my comfort zone. But alas, those wheels were too small.

So then I upgraded to the 21" x 1.6" motorcycle rims. I was shopping for tires at the same time - had to make sure not to exceed my (generous, but not huge) rear chain stay width. Once I found a road/slick tread, 21" x 3" tire, I committed (was hoping for 21" x 2.6, but that was the best I could do). I knew the tire was tubeless, I just didn't know what that meant as far as installation was concerned.

The tubeless tire is impossible to install by hand. I tried every trick I could think of or read about. And the motorcycle shop, with all the right machines and tools - they ended up doing a manual install, took 3 guys and 3 tubes to get it done. But I'm too far into these parts now to turn back, I'm pressing forward.

So, I won't be carrying a spare tube. My contingency plan for tire failure is to carry my triple-A card and/or cab fare. I am not worried about standard puncture flats - the thick rubber will shield me from that, and I don't ride in the s#i+ filled gutters along the road margin. My worry is that my tubeless rim conversion will be the failure point. But as described above, running this tire/rim combo with a tube is not an ideal solution either, so I might as well try tubeless.

I'm still flexible as to [how] I go tubeless... I can use the duct tape and Stan's fluid, or go with the silicone linked above. I prefer the silicone method because it appears it doesn't need the twice a year infusion of more fluid.

The one piece that I'm concerned about at present is geeing the wheel tight & true before sealing it, because once sealed turning spoke nipples can compromise the seal. Wish me luck guys!

[kfong]

From what I've read, the Stan's stuff gets dried out due to the porous nature of the tire. If you don't have air leaks you aren't loosing any fluids. I don't think the silicone will prevent this. The seal created by the duct tape is pretty air tight and the membrane water proof. Since you can't easily take your tire apart, the silicone seal would give you a peace of mind since it would be more permanent.

Last year was my year for flats, I got so many I had to find a better solution than the standard tube and liner I was using. Hopefully this current combination works out and still allows for field repair. Hopefully your solution works out for you.

[MattyCiii]

From what I've read, the Stan's stuff gets dried out due to the porous nature of the tire.

That's great info. I had not stopped to think about why Stan's fluid needed re-application. I'll do some reading up on this and see what else I can find. Perhaps the fact that this is a tubeless tire will weigh in my favor - maybe it's less porous than a tubed MTB tire since it's designed to hold the air itself. Either way I need to seriously consider this approach.

I should also check my motives. I enjoy doing bike maintenance, so I need to ask myself what's so bad about pouring a little fluid into the tire twice a year.

In the end I already have been hedging my bets a bit. I bought rim tape and the inflation nozzle from Stans, and Gorilla duct tape is available at the local hardware store. At this point it's no harm to go ahead and pick up the fluid and associated fill syringe.

Maybe I'll use just a little silicone - perhaps on the outside (see below), as insurance. At this point a few more ounces of weight won't kill me.

[kfong]

I think you want to seal from the inside out. That way the pressure works for you. It forces the tape against the rim, same situation with the silicone, you want it be backed by a hard surface.

[MattyCiii]

Well I went with the Stan's type tubeless. The Stan's rim tape has a nice feel to it, but is thin and lightweight. I taped up the rim and use a Stan's stem. I just dropped the wheel off at the motorcycle shop to have the tire installed, now I'm counting the hours till he calls with it finished. Hopefully by 5:30 tomorrow so I can pick it up on the way home.

Once that wheel is done, I'll have a rideable bicycle, and I'll be able to start designing the electrics portion in earnest.

[MattyCiii]

I picked up the front wheel tonight, mounted it and took a few spins. Gosh this thing is a ponderous beast! I geared it quite low for pedaling- which is nice, I think I can actually get it from place to place (slowly) by human power alone. The Schlumpf High Speed Drive will be useful for adding power to the (to be installed) electric drive... but without E-Drive, it's impossible to pedal the Schlumpf in overdrive even while the NuVinci is in its lowest gear.

I seem to be having trouble with the Lefty suspension, more on that later. For now, at least I have a bike I can pedal - and can pose upright while I measure for and design mount points for the Recumpense DaVinci power assist!

[fractal]

you're gettin there matt! i really want to see how you will design the mount for the drive. this is something i might be interested in doing for another project in the near future.

[MattyCiii]

You bet!

I really skimped on the pictures, because I was running out of time to put both bikes together before leaving town on a 5-day weekend. I was highly successful... Achieved all my goals. I just didn't take any build pix
I should be able to get some glamor shots though this weekend.

[MattyCiii]

Rode the bike 8-10 miles tonight with Critical Mass. Fun times, but toting all that weight around sucked the life out of me. It'll definitely be principally powered by LiPo, with human power as an auxiliary system...

[fractal]

Rode the bike 8-10 miles tonight with Critical Mass. Fun times, but toting all that weight around sucked the life out of me. It'll definitely be principally powered by LiPo, with human power as an auxiliary system...

LOL!!! what voltage are you going to run it at? I see a lot of mid drives running at lower voltages, why is that?

[MattyCiii]

LOL!!! what voltage are you going to run it at?

I'm aiming for 12S LiPo, for ~50V hot of the charger. That's all the Castle HV160 can take. I'll probably start with 12s2p, since the frame is so unfriendly to holding bricks in the triangle.

I see a lot of mid drives running at lower voltages, why is that?

Well I wouldn't exactly consider this build a mid drive. IMO a mid drive is defined by its use of the bicycle drive gears. I'll be putting e-power into the NuVinci on the left side, sort of a parallel hybrid to human power on the right.

But as an RC drive, 50V is somewhat low versus DD. That's because the controller I chose yes, but also because the KV of the motor. The motor is an AstroFlight 3220, 8 turns of wire. This gives me a KV of 84 RPM per volt. At 50v, we're talking a 4200 RPM motor! I have to reduce that speed back down to something useful, and with the large diameter of those monster tires, I have to gear it down by like 8:1.

[MattyCiii]

Here's the bike in its rideable form:

[MattyCiii]

Here are a couple of options I'm considering for DaVinci drive placement:

Option 1:
In front of and above the rear wheel. This will bring the weight of the drive closer to the suspension pivot, minimizing the impact of that unsprung weight. The down side is that it makes the chain line longer, and I don't have a lot of clearance past that 3" wide rear wheel. The suspension triangle is very curvy there as well, which will make mounting the drive a challenge.




Or:

Option 2:
Place the drive on the left upper chain stay, a little above and forward of the dropout and rear brake. This makes a shorter chain line, and should make for easier mounting of the drive system some flat surfaces and bolt holes available on the custom dropouts). Down sides to this are moving the unsprung weight rearward on the suspension, very little heel-strike clearance, and drive system closer to road debris/water splashes.

[sn0wchyld]

ill take it there's not enough space between the wheel and the bike, between the 2 swing arms? I'd think option 1 is best, but you'll want to check that you wont end up hitting the frame under full compression. I've had a small pannier attached to my seat, and even with the smaller wheel it got hit by the tyre fairly often.

[MattyCiii]

ill take it there's not enough space between the wheel and the bike, between the 2 swing arms?

Great question. It would be really awesome to have the motor right on top of the upper arm and the large reduction pulley & freewheel inside that space. Sadly the parts I have are too big. But I think if I change some variables, it will work out. For all its stiffness and cool-factor, the DaVinci drive is bigger than the V4 drive in many dimensions. I think I'll try my V4 drive here and see if it'll get the motor where I want it. Also the large belt pulley is just a smidgen too big... I got the 5:1 pulley and I know Matt sells a 4:1, so perhaps a 4:1 pulley will fit.

It will likely require custom brackets to hold things in place firmly and correctly, but I had a great experience with bigbluesaw.com making brackets for my other bike, so now I'm confident that if I can design it, they can build it.