BBSxx on Big Hit donor

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
Post Reply
Davescustom   1 mW

1 mW
Posts: 17
Joined: Apr 03 2015 4:18pm

BBSxx on Big Hit donor

Post by Davescustom » Nov 24 2017 5:12pm

After building some years ago my first ebike (I think i have a topic about it somewhere on this Forum), I bought, in 2016, a Qulbix 76R frame.. but after receiving it, I realized that wasn't the thing I wanted (I'm selling the frame, it's new..) .. since then the project was "on hold". on july i decided to make it, but on another direction.

So I decided to share my new project here.
I don't have many tools and only an Arc welder, And don't have access to Chromoly.. The first part of the frame building i done it in my parents garage during my vacation there. Now for finishing it i have only a balcony.

The happy (or not) donor was a Specialized Big Hit. (Bought used)
Image

After some work on software Linkage I designed the shape and here is the "pre" result, with my "jig" .
I wanted something cool looking on the FR/DH zone..
Image

Here is the project first shape.. at the time I didn't have the motor yet.
Image

When the motor came... it was not the perfect fit and some mods were needed. (now in balcony)
Image

I took it all apart.. and redone the motor part (this time the tubbing is over the motor)
Image

This is the central part of the frame (4.7Kg).. not bad I think, since it's not Chromoly and I have a lot of tubbing...
Image

More updates to come.. but this is a slow project, I have all winter to make it....
Last edited by Davescustom on Dec 06 2017 10:59am, edited 1 time in total.

SlowCo   1 MW

1 MW
Posts: 1643
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: BBSHD on Big Hit donor

Post by SlowCo » Nov 24 2017 7:41pm

Nice project!
But why not put the BBSHD on the original frame? Doesn't that fit or did you just want to build a frame?

Davescustom   1 mW

1 mW
Posts: 17
Joined: Apr 03 2015 4:18pm

Re: BBSHD on Big Hit donor

Post by Davescustom » Nov 24 2017 11:10pm

SlowCo wrote:
Nov 24 2017 7:41pm
Nice project!
But why not put the BBSHD on the original frame? Doesn't that fit or did you just want to build a frame?
It fits on original Big Hit BB, i think the only problem to be solved is the chainguide mount of the frame. But, the frame have no place for battery (most of FR/DH frames doesn't have).

Davescustom   1 mW

1 mW
Posts: 17
Joined: Apr 03 2015 4:18pm

Re: BBSxx on Big Hit donor

Post by Davescustom » May 05 2018 12:40pm

et voilà. 98% finished... it took me almost a year but like I said it was a "not urgent" project.
ebike1.jpg
ebike5.jpg
ebike2.jpg
ebike3.jpg
ebike4.jpg
I have a second set of wheels with DH rims and DH tyres, not fancy color!

User avatar
fechter   100 GW

100 GW
Posts: 15179
Joined: Dec 31 2006 3:23pm
Location: California Bay Area, USA

Re: BBSxx on Big Hit donor

Post by fechter » May 05 2018 1:16pm

Great build!

How does it ride?
"One test is worth a thousand opinions"

User avatar
zro-1   1 kW

1 kW
Posts: 360
Joined: Jul 31 2012 9:09am
Location: Atlanta, GA
Contact:

Re: BBSxx on Big Hit donor

Post by zro-1 » May 05 2018 2:00pm

Very nice work! I'm quite impressed with how it turned out. Its a very clean and professional looking build.
~01~

Lurkin   100 kW

100 kW
Posts: 1428
Joined: Jan 18 2015 4:31pm
Location: Melbourne, VIC, AUS

Re: BBSxx on Big Hit donor

Post by Lurkin » May 06 2018 5:29am

Very nice work, the gap at the top creates an EOM vibe to this, really like your framework! 8)

Did you replicate the Bighit's geometry or depart from it?
Would it be possible to see some more of inside the battery area?

I think building my own frame will be on the cards for the next project!

User avatar
Matador   100 kW

100 kW
Posts: 1042
Joined: Jun 29 2016 10:00pm

Re: BBSxx on Big Hit donor

Post by Matador » May 06 2018 8:27am

Love it !
What`s your battery specs ?

Davescustom   1 mW

1 mW
Posts: 17
Joined: Apr 03 2015 4:18pm

Re: BBSxx on Big Hit donor

Post by Davescustom » May 06 2018 11:38am

The battery is 58.8v (full charged) 26.4A, not the best capacity but i had those 2400mA cells for free (154 cells)! I am planning to build a smaller pack with better cells (3200mA or higher and 3C discharging current).

I modded a little bit the geometry of the Big Hit frame on the rear suspension (I bought the Linkage software) to move the shock outside the frame, making more space for battery. If it was now I would maybe build it different, with another type of frame, to look even more "OEM". I choosed the Big Hit frame because it has asymmetric dropouts, so I can fit the biggest tyres possible without chain problems.

The Head tube Angle is 67 degrees (can switch to 63 by mounting the rear shock on 2nd position but for my use now the 67 is fine) and the wheel base is a little bit longer (1185mm with 67 degrees head angle and 1200 with 63) due to longer chain stay (445mm). The rims are 47mm wide with 2.3 Crazy Bob tyres. I have 225mm front rotor and 203 on the back. The battery is removable. The all thing is on heavy side... a little bit over 35Kg, I hope that with the smaller pack it goes down to little above 30Kg. (not bad considering that i have no lightweight frame materials.. double crown fork, big rims, big brakes, big rear shock)

The things that i still have to do/adapt:
- Chain guide
- Chain guard
- Swap the fork coil (it as the silver but i already ordered the red one )
- Smaller size battery pack
- PAS switch
- Throttle switch
- Brake cutoff switch
- Covers for "holes" in the frame (where run the cables and future switches inside the frame)
- Try the 42T chainring that i have here

Edit: Photos
ebike7.jpg
ebike7.jpg (173.86 KiB) Viewed 1585 times
Battery pack
ebike6.jpg

Raisedeyebrows   1 kW

1 kW
Posts: 392
Joined: May 13 2017 1:39pm
Location: Oregon/South Point Hawaii USA back and forth

Re: BBSxx on Big Hit donor

Post by Raisedeyebrows » May 06 2018 1:13pm

Wow that is nice, BBSHD is great off road motor, quiet and fairly efficient so you can ride for hours if you pedal quite a bit.
Yuba Mundo w/BBSHD
Specialized Hard Rock w/9c clone, statoraid, hubsink
Trek Fuel 90 w/BBSHD
Above all run on 14s4p 52v li-ion
Ecobike folder 36v
Currie Flyer scooter 24v on 24ah of SLA

Every trip made with electric bike is one less car trip, saves money, no toxic fumes, less noise, less impact on roads.

Post Reply