eCortina v3 - Last of the Cortina Series

[RWP]

The triangle of the Cortina is just too small but I have so much invested in the bike that, at least for me, it made sense to do one more drive iteration using this frame.

I wanted a drive system that I could mount directly to a round bike tube and I wanted a motor plate that was made for the 80x Turnigy motors. I also wanted to try a belt drive first stage again and get as much reduction as I can in the first stage.

I asked Matt more than a year ago if he was going to make motor plates for the 80x Turnigy motors and he said and I paraphrase "possibly but not high on my list". It was not a no, but it was not a yes either. I asked several times and finally decided that if I want one I would have to make it myself. I also needed a different mount for the drive, the mount Matt provides makes it hard for me to mount motors the way I want. It's taken more than a year but now I want to show what I have come up with.

The 25mm wide sprockets are from Matt. The tube clamp, motor plate and tensioner (really to get more wrap around the motor pulley) I made.

8085 Turnigy with stock wind (will probably rewind this in the future and put in sensors). HV160. 4 or 6 - 25C 6s Turnigy batteries for 48v 10/15Ah.
24" wheels. 13t Crossfire on Matt's adapter. Stand alone high amp CA.

So, as you can see, lots of appreciation for what Matt has done and continues to do.




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[RWP]

reserved

 

[neptronix]

Very nice,a poor man's recumpence drive. Question.. could you produce more of these fairly cheap?

 

[farmkid4]

^+1

Very nice and tidy! What kv is that motor 250?

 

[Thud]

RWP,
So how long do we have to wait to hear your opinion on driving the bottom bracket?

Also how much reduction did you manage in the 1st stage?

I still love the lines on that Cortina
a perenial favorite of mine.

 

[RWP]

Very nice,a poor man's recumpence drive.
Question.. could you produce more of these fairly cheap?

Thank you.
Regarding production - probably not...but you can PM me for the gory details...and I can tell you up front it won't be cheap...sorry.

^+1 Very nice and tidy!
What kv is that motor 250?

Thanks!
The stock 8085 motor I am currently using is 170kv
The stock 80100 motors come in 130kv and 180kv

RWP, So how long do we have to wait to hear your opinion on driving the bottom bracket?
Also how much reduction did you manage in the 1st stage?
I still love the lines on that Cortina
a perenial favorite of mine.

Thanks Thud! First stage is 20t to 95t or 4.75 to 1.
I will post more about the rideability as soon as I know more. These days I am taking everything very slow.

But what I can say is that because it's geared to top out in each gear at 25mph - 31mph and 39mph - pedaling is a joke. Top gear is the only useful gear for pedaling, and it tops out at about 10mph and I am spinning the pedals pretty fast, and I geared it lower so the motor will not have to pull such a high gear when starting up.

Because both chains are BMX I modified the derailleur to allow for the wider chain and I used only 3 sprockets on the cassette with 2 spacers between each sprocket to accommodate the wider chain. Shifting is 2 clicks of the trigger shifters up and down - not fast but it works.

 

[renago]

Nice job RWP !
I am planning something similar , and will be very interested to know how you bike performs on off road .
i mean if the motor is able to get you over hills and severe obstacles without tuning upside down .
if it has enough power and traction to climb .
many people is just waiting from your lips or camera !!

Renago

 

[spinningmagnets]

Beautiful work as always, RWP. If motor supplies from China came to a halt, the 80-85 outrunner in a variety of low kVs (with an integral air-fan) is the motor I would most want US garage-machinists to start making first.

I'm thinking that if it could be wound in WYE and with the appropriate wire, the kV could be somewhere around 75-ish, and hopefully it could run well with a single reduction stage.

You should borrow a Thudbuster to test-run...I think you'd really like it.

 

[spinningmagnets]

Finished the story on Roys eCortina: http://www.electricbike.com/custom-build-gallery-roys-ecortina/

 

[cheekybloke]

Because both chains are BMX I modified the derailleur to allow for the wider chain and I used only 3 sprockets on the cassette with 2 spacers between each sprocket to accommodate the wider chain. Shifting is 2 clicks of the trigger shifters up and down - not fast but it works.
fantastic build mate,could you add more detail about your modified shifting system,what sprockets did you use that run on a bmx chain and what sizes etc?
i am sure lots of people would be very interested.
darren

 

[RWP]

fantastic build mate, could you add more detail about your modified shifting system, what sprockets did you use that run on a bmx chain and what sizes etc? i am sure lots of people would be very interested. darren

Thanks Darren!
I took apart a standard cassette and eliminated all but 3 of the sprockets. Then put more spacers between them to get the chain clearance I needed. I also had to mod/widen the derailleur cages to allow for the wider BMX chain. The bikes in storage so it's hard to get at the bike now -- I do not remember the sprocket sizes...but I used a ratio calculator that I made in Excel and chose sprockets based upon their ratios and speed I wanted in each gear. I went with BMX chain because I did not want to end up with stretched and/or broken chains.
Hope this helps.

 

[cheekybloke]

fantastic build mate, could you add more detail about your modified shifting system, what sprockets did you use that run on a bmx chain and what sizes etc? i am sure lots of people would be very interested. darren

Thanks Darren!
I took apart a standard cassette and eliminated all but 3 of the sprockets. Then put more spacers between them to get the chain clearance I needed. I also had to mod/widen the derailleur cages to allow for the wider BMX chain. The bikes in storage so it's hard to get at the bike now -- I do not remember the sprocket sizes...but I used a ratio calculator that I made in Excel and chose sprockets based upon their ratios and speed I wanted in each gear. I went with BMX chain because I did not want to end up with stretched and/or broken chains.
Hope this helps.

many thanks i will be constructing the same very soon.
darren

 

[RWP]

fantastic build mate, could you add more detail about your modified shifting system, what sprockets did you use that run on a bmx chain and what sizes etc? i am sure lots of people would be very interested. darren

Thanks Darren! I took apart a standard cassette and eliminated all but 3 of the sprockets. Then put more spacers between them to get the chain clearance I needed. I also had to mod/widen the derailleur cages to allow for the wider BMX chain. The bikes in storage so it's hard to get at the bike now -- I do not remember the sprocket sizes...but I used a ratio calculator that I made in Excel and chose sprockets based upon their ratios and speed I wanted in each gear. I went with BMX chain because I did not want to end up with stretched and/or broken chains. Hope this helps.

many thanks i will be constructing the same very soon. darren

Good luck with your build!

 

[steven.b.watts]

Hey, sorry to bring this back from the dead.

Why did you change from the Astro 3220 to the Turnigy 8085? I have a build going on right now and I'm trying to decide between the two. It looks like the Astro comes with the motor mounts on the same side as the drive shaft though and that won't work for me. Waiting to hear back from Astro to see if they can put the mounting holes on the opposite side as the drive shaft.

There's a link to my build below if you wanna sneak a peak

 

[RWP]

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