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

[noshortcuts]

Dave, I'm excited to see you offering a pedal assist model. As an aging mountain biker who loves to stay in shape by biking, I've been looking for a small and light assist without having to buy a new bike like the Specialized...

 

[tangentdave]

zomg, torque sensing ebikes are such a great workout and I get to ride at trail speeds that are more fun than a normal pedal bike.

small and light assist

Give me a few weeks...I've got something related to this coming down the pipe...

-dave

 

[noshortcuts]

zomg, torque sensing ebikes are such a great workout and I get to ride at trail speeds that are more fun than a normal pedal bike.

small and light assist

Give me a few weeks...I've got something related to this coming down the pipe...

-dave

Added information about the current 7lb version or something else?

 

[litespeed]

That drive is so inconspicuous.........

Awesome I tell ya.

Tom

 

[Sloppy Floyd]

Can't wait to see the finished product. I'm looking at this new PAS 3Kw kit as a one motor for both my bikes kit - a commuter and full sussed MTB. I would really like to see the THUN sensor in an ISIS bottom bracket.

Also, would love to see a "quick disconnect" for the motor from the mounting brackets and connections so as to quickly move the motor and CA. I would gladly pay for an additional controller for this option. Thanks for the update Dave!

 

[lightrush]

Living the PAS dream!

 

[dtx1]

Hey Dave,

are there any technical reasons why one couldn't use a BB Torque sensor that senses both sides?

 

[tangentdave]

I'm in contact with NTCE, they're the German company than produces the sensors for both the THUN square taper and NTCE ISIS torque sensing BB's that are available. I didn't think of the reason double sided torque sensing is more difficult either. The right crank acts directly on the chainring whereas the left crank torque is transmitted through the spindle, where the measurement occurs. The solution is a mechanical one, make the inner diameter of the BB larger as pictured.

I've been riding on the square taper THUN, it works great. NTCE is willing to produce the ISIS version in the correct spindle length to fit the kit (we need 30mm of spindle stickout on the chain side, plus 6mm to accommodate the mounting brackets, their existing dimensions aren't compatible with the freewheel crankset). There would be some costs associated with the custom part that I have to figure a way to cover, I want the ISIS version too.


-dave

 

[dtx1]

Hey Dave,

thanks for taking the time to answer all my silly questions. It might take some time to acquire the necessary funds but someday im gonna get a tangent of my own!

Keep up the great work and thank you!

 

[briangv99]

NTCE is willing to produce the ISIS version in the correct spindle length to fit the kit

Hey Dave, when you check in with NCTE can you see whether a 100mm bb shell would be possible? I assume there would be a reasonable market for 100m with fat bikes becoming popular.

 

[PtotheK]

NTCE is willing to produce the ISIS version in the correct spindle length to fit the kit

Will the new smaller PAS only kit have this new ISIS version torque sensor?

It's all exciting news Dave! Can't wait to see how it all looks.

 

[PaulD]

I've been riding on the square taper THUN, it works great. NTCE is willing to produce the ISIS version in the correct spindle length to fit the kit (we need 30mm of spindle stickout on the chain side, plus 6mm to accommodate the mounting brackets, their existing dimensions aren't compatible with the freewheel crankset). There would be some costs associated with the custom part that I have to figure a way to cover, I want the ISIS version too.

I'm using the ISIS NCTE with 68mm bb shell. They say MOQ of 500 units for a different spindle length and shell size. Back when I inquired (about a year ago), they said they didn't have enough other customers interested in 73mm or other sizes. BTW, I'm using freewheel cranks but with an ACS freewheel, I don't think a White Industries or other thicker freewheels would fit with the 128mm spindle due to the outboard bearings.
Let me know if you need more volume to meet the MOQ. Perhaps we can get others interested as well (Justin? Luna?)

 

[Rube]

Continual development of this setup makes me think I need one. If not for any reason but the solid engineering and power. I'm a bit concerned about noise and was considering a BBSHD but the great design features have swayed me to get one of Dave's kits as soon as I sell motorbike #2. Thanks for sharing the development process.

 

[PtotheK]

Continual development of this setup makes me think I need one. If not for any reason but the solid engineering and power. I'm a bit concerned about noise and was considering a BBSHD but the great design features have swayed me to get one of Dave's kits as soon as I sell motorbike #2. Thanks for sharing the development process.

Couldn't agree more mate. I'm actually going to use the money from selling my motorbike to buy a Tangent too! I'm hopefully getting one shortly. Just waiting to see the how the smaller lighter PAS version will look when Dave has finished working on it.

 

[izeman]

An isis double side torque sensing bb would be an instant buy. Having only left side sensing makes it useless for my needs. I'd like to start the bike motor supported uphills. So just put the foot on the pedal and press it dowb would make the motor act.

 

[lightrush]

@izeman If I'm not mistaken, CA can support that use case if you set a minimum throttle output for PAS. That is I think you can make it supply predefined amount of power as soon as you push on the pedals regardless of what the torque sensor tells it at the moment.

 

[tangentdave]

A quick blip of the throttle gets the motor going anywhere

But yes, dual sided torque sensing would be great. It sounds like that won't be possible with NTCE without a custom BB shell...

 

[robertpaulson]

wow, if there is any way to make a lower power rated slot in gearbox that is much quieter i would gladly buy the 3kw torque sensing set-up and the 'stealth' gearbox for use at lower power output. imho its a product like this that will make ebikes massive - quiet, well made, unobtrusive, torque sensing and an easy retro fit - think of all those cheap 26er all mountain sleds out there begging to be fitted with super grippy fat tyres and ridden at the local flat trails like they were whistler bike park :lol:

 

[Ecyclist]

Torque sensing BB is a great idea.

 

[tangentdave]

Just a little warm up. Don't try this stuff on your average ebike.

[youtube]yXvS-e118oU[/youtube]

 

[Sean9002]

Just a little warm up. Don't try this stuff on your average ebike.

[youtube]yXvS-e118oU[/youtube]

Nice loamy trails you have there man!

 

[tangentdave]

We need a week of sun up here in the PNW, then these trails will be ready to rip.

 

[drew12345]

Sweet vid!

 

[Sloppy Floyd]

Any videos of the PAS in action?

 

[tangentdave]

Videos coming. I have my hardware on a test stand now since it's so wet outside. Watching videos of a bike on cruise control on a stationary trainer isn't all that interesting. I am amazed the cheap magnetic trainer hasn't caught on fire yet, I'm dumping 800W into it for about 40Ah at a time (takes 40mph of wheel speed!)


-dave