Dave's 80:1 RC mid drive kit build log

[knurf]

I have to chime in here as well; I've ridden mine 1800 miles both on and offroad, Dave has taken well care of all my troubles with quick answers and effective solutions.
It's an expensive kit but the support is nothing short of amazing. Thanks!

 

[macribs]

Nice ride maker. That is one lightweight mid drive. Battery in back pack [strike]or mounted on the fork?[/strike]

Edited; I thought I spotted a triple crown fork but I was wrong.

 

[m4k3r]

Nice ride maker. That is one lightweight mid drive. Battery in back pack [strike]or mounted on the fork?[/strike]

Edited; I thought I spotted a triple crown fork but I was wrong.

Thanks macribs! This thing shreds, the placement of the mid-drive on the Knolly makes this one nimble monster! Balance of the bike feels just like it did when she was analog. No clearance issues with the tire during travel either. So addicted...

Edit: Yes, backpack mounted battery pack! :lol:

 

[robertpaulson]

Is anyone out there riding the 3kw pedal assist that can provide some feedback? If you have direct experience of bafang/commercial mid-drives i would be really grateful for any guide on what sort of dB it is putting out at lower power levels (500-750w) once broken in compared to a bafang and how the torque sensing compares to units like the brose and shimano steps.

thanks in advance

 

[RobertC]

Is manufacturing speed an issue? Tool wear?

http://blog.cnccookbook.com/2017/06/07/customer-spotlight-voxel-innovations/

Check this out Dave, they are looking for clients!

 

[tangentdave]

This is an interesting method. The higher the accuracy of parts, the better the gearbox runs.



The 'high value' components part makes me think the cost per piece might be too high, but I'll ping 'em. I'm also exploring custom broaching and gear hobbing tools to create our round tooth profile. CNC works fine, but the small 1/8" end mill I need to use on the eccentric and ring gears requires special tool paths to counteract tool deflection (takes a while in the CNC). More spring passes doesn't solve the deflection inaccuracies.

Gear broaching experts wanted...is a round profile broach possible? I want to broach the ring gear, the inward facing teeth. Pitch circle is about 3", diameter of the dedendum is about 1/8".


-dave

 

[macribs]

You should drop them an email, seems to me they are drumming up customers to make a base reference portfolio. Something as precise as your gearbox should bring cred to them and their product. From what I read they started the development with a used CnC machine. So I guess any cnc will do as a base. Then hook it up to their solution. Maybe you get lucky, or at least if they are close by you they let you run a batch on their equipment. They got to start somewhere, and I guess they target a market that is all about references and proven track record.

Their solution may speed up production as well, as the tools dont break, nothing overheats and the material that are being removed are "somehow turned into softer material". Some time at their mill should make for a great test batch. And who knows from there?

 

[HamsterPower]

Is manufacturing speed an issue? Tool wear?

http://blog.cnccookbook.com/2017/06/07/customer-spotlight-voxel-innovations/

Check this out Dave, they are looking for clients!

Don't mistake making the items vs the making machinery for others to make the items. These guys are making machinery and even though they have no tool wear, they likely burn through chemicals just as quickly.

Different? Yes
Cost effective? Maybe, shall see.

 

[RobertC]

Is manufacturing speed an issue? Tool wear?

http://blog.cnccookbook.com/2017/06/07/customer-spotlight-voxel-innovations/

Check this out Dave, they are looking for clients!

Don't mistake making the items vs the making machinery for others to make the items. These guys are making machinery and even though they have no tool wear, they likely burn through chemicals just as quickly.

Different? Yes
Cost effective? Maybe, shall see.

I dunno.. To me, it seemed they started with a used CNC to bootstrap. Now they have something working, and can use the new machine to build new templates, etc.

Judging by the photo with all the large tanks, and the caption "Here’s one of their PECM machines and the waste water treatment cell…" it sounds like they are recycling the liquids.

One way to find out, ask them!

 

[macribs]

It didn't say anything specific about type of electrolyte. In its simplest form electrolyte could be saltwater. And that might actually work too. It seems the clue for their solution is the current discharge pulses and the controller. The term saltwater might be loose, as salts comes in many forms and will dissolve in water. But as they say the point is to create corrosion, some sort low PH solution is probably added. Again in the simplest form it could be saltwater and a dash of acid, or more likely salts are a biproduct. Unless they needed very specific chemical bondings for their speedy corrosion process they likely made their electrolyte as easy and readily available as possible. As I read it is not the strength of the acidic solution that create corrosion, it is the combination of current and electrolyte. Meaning PH might not need to extremly low.

If the usage of saltwater and cheap acid is all that it takes combined with their controller and current pulses the savings from less broken tools and possible more rapid manufacturing likely will be well worth it for at least mid to mass production. I guess there is a brake even point in regard to how many batches a month/year needs to be made to get ROI, but looking into the possibilities to be their "poster girl" with the tangentdrive might work. They already got the machinery, and if they grant Dave access they both might come out on top.

 

[RobertC]

The solution is there to carry a current, and to carry away the unwanted material. I would think this is changed depending on the material. ie, you want to machine gold, use aqua-regia, titanium, use X, etc. These are all simple reversible reactions, so recycling may be easy. Swap the DC cables, and then insert a lump of your base material, and run it all backwards, re-plating your material on the lump. This could mean multiple steps, as with steel, you would still have the carbon, etc in there after having pulled the iron ions out. Leave the harmless stuff in there, put it down the drain.

To me, the hard part would be positioning the electrode with regards to the part.

This seems to require convex/concave parts to work.

Anyway, slick idea! Hard to believe that nobody thought of it yet. Is this patentable, or only a trade secret?

 

[giblet]

2014 Knolly Warden

Loving your bike dude!! Looks awesome. I like the position of the motor too... does it fit there with no modification?

PS Are you in the UK? I'd like to go shredding with another Tangenteer. It's lonely being the fastest bike in the woods

 

[Sloppy Floyd]

Bench Test w/ Phaserunner and BatteryBloc 72v battery...just autotuned with no custom settings.
https://youtu.be/yL9ssWnpuWY

 

[m4k3r]

Loving your bike dude!! Looks awesome. I like the position of the motor too... does it fit there with no modification?

PS Are you in the UK? I'd like to go shredding with another Tangenteer. It's lonely being the fastest bike in the woods

Thanks man, means a lot! Couldn't have done it without Daves sourcery! He really is a wizard when it comes to this (and extremely patient). Only mod i can think of right now was adding the mud guard to protect from rocks. Also, need to shave/dremel down one of the strap bolts to make room for the tensioner wheel (bolt barely rubs on wheel once installed, still works though). Other than that it's pretty straight forward as with any other tangent install!

No, i'm on the other side of the pound (just south of Dave actually) in California. And i know what you mean, i've conviced some other friends to build ebikes (one tengent, one BBSHD and another Tangent on the way soon) so I've finally got some buddies to shred with. So friggin addicting!

 

[litespeed]

Sharp looking ride!

Tom

 

[m4k3r]

Here's my completed project.

Looks amazing! Great job....

How was the position on the spring loaded tensioner for you? I had a slight issue getting the small cog to line up just right on the chain (but the knolly mount was a completely different animal). Did you have to mod it at all?

 

[m4k3r]

My chainline for the motor is perfect, the tensioner is maybe 2 mm inboard of that. Works fine, though.

Yea same here, i ended up notching out a small slot in a washer (so the spring can sit in it) and put that between the mount and tensioner. Help a ton but still not perfect. Gonna try shaving down the arm of the tensioner to bring the cog outboard a bit more. Works fine right now, just makes a ticking noise as if it wants to shift lol, like when the rear derailuer isn't set right. Still hardly noticeable, just my OCD kicking in.

 

[Mugenski]

I've put off building an ebike for a couple years now. It seems every year or so I sit down and read a whole bunch on the latest kits and then do my best to continue playing the waiting game, knowing that the tech is continually improving. This time around though I have found the kit. Dave this thing is freaking BEAUTIFUL!

Going to be putting it on a Giant Reign (possibly glory as I just realize reign isn't threaded BB). Seems like from what I'm reading that the castle still has the best starting torque? I was leaning towards a phaserunner but from what I've read the castle seems to have a better start. I also have a castle programming card already so I guess that settles that...

All that said the website says preorder however when I try to order it just claims out of stock. I'm guessing I need to call Dave and get my name on the list?

 

[Alex07]

Tangent requires more regular maintenance, greasing every 100 miles

Since when is grease a consumable ? that's sounds like a design fault that the grease overheats and evaporates as the gearbox is passing so much power in such a small volume it cooks the grease? which means it has also burnt up and stopped lubricating?

Is it not possible to use oil in the gearbox like some other gearboxes leg.the AFT mid which is similar power and size? oil would be a lot lower maintenance and lubes better too so the gears should last longer as well ?

 

[spinningmagnets]

I'm sure oil would work, but grease will be quieter, don't you think?

 

[dtx]

Oil is also nasty to work with. With the grease you can just pull it apart and put it back together without needing to drain it

 

[litespeed]

From the web site,

'Maintenance

The unit is supplied with a 20mL syringe of VigoGrease RE0. This is 2000-4000 miles worth of grease. Only Vigogrease RE0 should be used- this is a special Grade 00 low viscosity grease, think oil that doesn't drip. Higher viscosity greases will cause the unit to overheat very quickly.

Every 100 miles of riding add 0.5mL of grease through the fill port on the front of the housing. The old grease will work it's way out the main bearing of the unit behind the freewheel. Wipe away the old grease during normal chain maintenance.

There is no regular maintenance on the inside of the unit, although it is completely user serviceable. "

Seams simple & reasonable enough to me to add to chain maintenance.

Small price to pay for 8 lbs of mid drive perfection in my opinion.

Tom

 

[tangentdave]

that's sounds like a design fault

It is. There are no seals inside the gearbox yet. We've been using Nabtesco Vigogrease RE0, made for cycloid reduction gears specifically. This stuff is very cheap and very good. Yes there should be grease seals but they need to be custom designed, and at this point, with limited development resources, refreshing the gearbox grease more often than not isn't a big deal (bigger fish to fry). Vigogrease RE0 gets into everything, it's designed to. This is a grade 00 grease, as close to oil as we can get- I've tried thicker greases (albeit in earlier gearbox iterations), they do seem to pad the gear teeth impact wise but the gearbox also heated up very quickly even with NLGI grade 2 (admittedly there is more testing to be done). This very thin Vigogrease circulates around the gearbox well with the eccentric motion of the gears sloshing it back and forth. All the drives use an M6 thread on the grease port, so combining a zerk fitting with this guy is the obvious choice:



I do think proper seals riding on stainless seal rings with oil inside the gearbox is the ultimate answer. We only want 10-20cc's of oil, changing it once a year should be quick, easy and obvious. Sealing the 14kRPM input shaft against hot liquid for years at a time isn't trivial, but it'll happen.

On other topics, Emil at Eggrider is designing and coding a dedicated control unit that will reside under braided sleeving just upstream of the ESC. It'll handle all the input and control logic and just output the R/C pulse to the ESC as we do now. I'll pot these guys to seal them and we're just getting motors spinning and much testing remains, but several customers have had issues with the Cycle Analysts (either issues accessing settings with the esoteric interface or possibly damaging the CA's with too much accessory current drawn by the THUN at 52V), and who wouldn't want to have the option of not strapping a Gameboy to their handlebars?



Much development and improvement still remain in regards to the entire kit and gearbox, thanks to the community and each Tangent customer for the understanding and support through the process.


-dave

 

[robertpaulson]

I have a BBSHD as well as a Tangent with proportional PAS.

The Bafang is very smooth and virtually silent. PAS programming out of the box is poor so you need to do your own before it works well. Once you do it is great but not proportional. That's not really a big problem but it means you will be adjusting your PAS levels when load changes. It's not set and forget.

Proportional PAS with the Tangent is great. You set your assist level for your type of ride and rarely, if ever, change it. Throttle is less needed as well compared to the Bafang. You just ride the bike like a bike and it does what you want. The difference is significant.

Regarding noise, the Tangent is louder without a doubt and it's noise is a combination of some whine and some coarse grinding type noise. It is not loud and cannot be easily heard by others off the bike, at least with PAS. The Tangent comes with some vibration. I find the noise just fine, I'd like the drive to improve in the vibe department.

PAS isn't perfect on the Tangent but the shortcomings aren't with the drive but rather the Thun BB and the CA. The BB only reads left side power and only has an 8 pole cadence sensor. These shortcomings combine with the CA firmware to cause a sluggish and inconsistent turn on from a stop. It's not as responsive as you'd like. You can mitigate that somewhat with CA programming, but when you do you will get some motor run-on when you stop pedaling. On the Bafang that's pretty bad but with proportional PAS its not a problem at all. You can't, however, fully eliminate the sluggish starts. I believe Grin knows about this and Dave does too, but the problem doesn't lie in anything Dave controls. Grin has promised improvements in this area. Other than the sluggish starts, PAS is pretty glorious.

So the TL;DR is that the Bafang PAS is smooth, quiet and refined so long as your program it yourself. The Tangent is less smooth, quiet, and refined but the proportional feature is fantastic plus the Tangent is a much nicer package with vastly more power and lighter weight. Tangent requires more regular maintenance, greasing every 100 miles, which might be an issue for higher mileage commuting.

Thankyou!

 

[devo1223]

Dave,

I look forward to seeing you again at the Lost Sierra bike race. Will you be bringing the same bike as last year?