EXTREMO - Scratch built 7kW billet frame scooter

Lightweight / Folding / Portable EVs - seats optional
HTTR   1 mW

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by HTTR » Jul 23 2021 4:34am

Looks great and must feel even better to see the parts come to life as you say .... looking forward to seeing your progress

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Jul 30 2021 1:28pm

quick preview of the ongoing assembly

Image

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Last edited by BigBlock on Aug 01 2021 5:08am, edited 1 time in total.
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Aug 01 2021 5:07am

getting closer with the 20S battery pack. I've tried for first time the copper + nickel sandwitch and it seems to work quite well.

I used 0,2mm copper bus bar with 0,15mm pure nickel strip on top -

Kweld @ 65J. The welds look a little bit burnt but they have a very good mechanical bond with the cell


Image

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by HTTR » Aug 01 2021 9:20am

BigBlock wrote:
Jul 30 2021 1:28pm
quick preview of the ongoing assembly

Image

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It really looks superbe and hope that it handles as well but as far as we can tell now it's clear that you have absolutely nailed the goad of the Vostok inspired design couple with a much simpler mechanical design. Fascinating project to follow.

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by StevieB-FPV » Aug 24 2021 10:33pm

BigBlock wrote:
Jun 17 2021 10:31am
I finally managed to fit a 20s12p that will give ideal balance between performance and capacity.

Using Samsung 30Q I will end up with a 36Ah pack and 150A BMS

Going with traditional layout will allow to spread the series connection by all 12 cells (150/12 = 12,5A) that should be managed with easier weldable nickel strips (0,15mm) without going with copper or copper + nickel sandwitch.

Image
Care to share the 3D model file for the Fardriver controllers? please? :D

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Aug 29 2021 5:37am

StevieB-FPV wrote:
Aug 24 2021 10:33pm
Care to share the 3D model file for the Fardriver controllers? please? :D
I modelled it very quikly for the fit check - it's accurate only in the dimensions that I needed

you can find the complete 2D drawing here: https://it.aliexpress.com/item/1005002326261717.html
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Aug 30 2021 9:12am

I completled the assembly of the 72V battery pack - I preferred to keep the BMS outside of the vinyl wrap for easier maintanance.

the wiring management will be quite weird - still need to place the fuses and discharge resistors.

Image
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Sep 09 2021 12:40pm

just completed the final batch of machined parts... now the fun begins :D

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Sep 09 2021 12:49pm

bearings pressed in place - the 30mm tapered bearing on the headtube feels stronger than many offroad bikes....

Image
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by HTTR » Sep 15 2021 3:43am

Really nice to see this vision becoming reality. Thanks for sharing. This is really impressive from conception to execution ....

I wish we had a scooter design as an open source project where people could contribute as per their skill and tastes.

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Sep 25 2021 9:15am

it's finally time to test it on the road !!! :D :D

Image
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Sep 25 2021 9:27am

the first shake down went quite well.

Handling: Very impressed by the suspensions and how confortable it's on rough roads. The doble air shock gives definitelly a lot or room to tune for eachone weight and preference.

Range: I drove it for approx. 70km with some fast shots and the battery had still 10% left. Using for crusing it would probably provide a range of 90-100 Km. Not too bad... The MOLICEL batteries never went over 45 degrees celsius.

Performance: it's simply a beast and a lot of fun to drive. I reached 80km/h..... and was a littlee bit scaried to keep going. But it can easisly reach 100 km/h - I will try the max speed in next trips. Probably I will add a steering damper for more firm feeling.

Brake: the Magura two pistons bite quite hard but the disks became very hot soon. I beleive 160mm is too small for such performance. I have to find out an upgrade to get more consistent braking performance

hope to post a video soon.
Last edited by BigBlock on Sep 25 2021 9:32am, edited 1 time in total.
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Sep 25 2021 9:28am

Image

Image

Image

Image

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Sep 25 2021 9:33am

I like this shot


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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by SlowCo » Sep 25 2021 2:03pm

BigBlock wrote:
Sep 25 2021 9:27am
the first shake down went quite well.


Brake: the Magura two pistons bite quite hard but the disks became very hot soon. I believe 160mm is too small for such performance. I have to find out an upgrade to get more consistent braking performance

hope to post a video soon.
Great result for the first real test ride :thumb:

As for the braking performance: variable regen braking combined with the manual brakes should help in that department.
If you can order a right side hub motor cover with disk brake mounting holes you could also make a dual disk brake front set up. That would devide the heat build up over two disks and calipers.

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by HTTR » Oct 01 2021 4:42am

Impressive work. One the one hand it looks narrower than the Vostok but that might be only in the pictures because the battery looks small in that deck. It’s a beauty either way and great to hear that it handles so well.

For the brake system, two pistons will indeed heat up quite fast. The MT5 are tried and tested on this category of scooters but if you are unfazed by using DOT fluid the Hope Tech 3 V4 are the top of the line.

You should definitely look into PMT tires, some 110x55r6.5 would look nice and suspect that you might be able to get away with the with the PMT 130/40R6.5 orginally developed for the Weped … might come out well with relatively large deck. Have also seem some Russians use the new chinese made 12x4.5r6.5 with great success.

180 disks sound like a great idea as it does not look like the deck would.

Either way .. hats off to you sir !!!!

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Oct 02 2021 5:14am

thanks for the feedback.

it's now time to work on initial improvements. I would like to see how a steering dumper will improve the handling, thus I got this little guy here:

Image
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Oct 02 2021 5:28am

I did a quick modelling in 3D to find the right spot. It was a little bit triky and I end up with a similar setup seen on Dualtron and other scooter of that size. There is litellary no space to put it in a more hidden spot.

I finally managed approx 30 degree of steering - the dumper will work also as steering stop avoiding excess stress on wiring

hope that it will improve handling over 80km/h with a more firm steering feeling.

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by HTTR » Oct 12 2021 7:41am

BTW, looking at the pictures again it looks like you put the tires on the wrong direction.

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Oct 12 2021 12:01pm

HTTR wrote:
Oct 12 2021 7:41am
BTW, looking at the pictures again it looks like you put the tires on the wrong direction.
yes, you are right - Just fixed after the shots :lol:
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Oct 15 2021 11:43am

just finished to machine the new bracket and installed the dumper -

I did a test spin today and the handling has drastically imporved :D Now I can reach 90Km/h with one hand !!

Image
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by RaicceKG » Oct 19 2021 12:23pm

Hi,
:bigthumb:

Is Extremo foldable.? It would be very nice if it is foldable.

Cheers,
Rajesh

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by BigBlock » Oct 20 2021 2:30am

yes, I designed the steering column to fold on the foot board - Just need to replace one bolt with a removable pin

Image
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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by RaicceKG » Oct 20 2021 5:28am

Hi,
Good Work :bigthumb: :bigthumb:

But that would be a normal folding like other ebikes. Since your design has a impact of VOSTOK, expected a different one.
If possible work on folding mechanism more.(Just my Suggestion).

Cheers,
Rajesh

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Re: EXTREMO - Scratch built 7kW billet frame scooter

Post by Chalo » Oct 21 2021 9:52pm

RaicceKG wrote:
Oct 20 2021 5:28am
Hi,
Good Work :bigthumb: :bigthumb:

But that would be a normal folding like other ebikes. Since your design has a impact of VOSTOK, expected a different one.
If possible work on folding mechanism more.(Just my Suggestion).
Why don't you ask how much it weighs before you wish it to fold? Do you want your refrigerator to fold? Your house?

If the thing weighs 50kg or more, as I suspect it does, then what's the use? You're not going to tuck it under your arm and carry it into a cafe or into your workplace. Many people would need help loading it into a taxi or other car. It might as well have better structural integrity and lighter weight by not folding.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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