Mongoose “Ugli Duckling” XR-200 Build

[e.s.dude]

Hi everybody. This is my first post; however, I have been doing a lot of reading here. I am a 16 year old H.S. student and I need reliable transport for school/work. I have saved some cash and have a license, but I don’t want to take on the hassles of owning a car now.

I picked up this donor bike on craigslist:

Pros: Inexpensive for mtn bike, Dual suspension, Front disk brake, Steal swing arms/drop-outs, Good street bike, strong welds, Easy to maneuver, Heavy duty rims and tires

Cons: Caliper brakes in rear; Uncomfortable seat, Heavy for an aluminum frame, No triangle for lipo pack/controller

 

[ecowheelz]

Welcome to the world of e-bikes! Have you chosen a system yet? Should be a nice bike for your first build

 

[e.s.dude]

Welcome to the world of e-bikes! Have you chosen a system yet? Should be a nice bike for your first build

Thanks. 48V system. First objective is to build a DIY expandable bulk charger. Starting with a 12S 2P LiPo 4-pack.
Dad says I can build anything I want, but before I plug it in, it has to be checked by one of his electrical engineer friends.

 

[e.s.dude]

Looks like I can switch the disc brake to the rear and the caliper brake to the front.
Anybody know the advantage of having the disc brake on front verses back wheel for a street bike?
What’s your preference?

 

[Sacman]

Looks like I can switch the disc brake to the rear and the caliper brake to the front.
Anybody know the advantage of having the disc brake on front verses back wheel for a street bike?
What’s your preference?

Hi,
Welcome to the forum and to the addiction.

The wheel has to be more straight and true for the V-brakes (rim brakes) to work well, whereas it doesn't matter too much with disc brakes. Once you get the motor mouted with torque arms and wires neatly tied to the frame on the rear it will be more of a PITA to remove if you have to true it.

 

[Sacman]

Thanks. 48V system. First objective is to build a DIY expandable bulk charger. Starting with a 12S 2P LiPo 4-pack.
Dad says I can build anything I want, but before I plug it in, it has to be checked by one of his electrical engineer friends.

I run a 12S 8P LiPo battery pack setup too on my Mongoose Blackcomb.
Take a look at my 1-plug charging setup using a Hyperion 1420i charger here...
http://endless-sphere.com/forums/viewtopic.php?f=14&t=33956&p=493233&hilit=hyperion#p493233

[youtube]AnC9aO1GedI[/youtube]

 

[e.s.dude]

Sacman, Thank you for sharing info. That is a nice build and clean charging system. I like the big apple 3.5” tires, too. I was budgeting for the Cyclops 2.4”s. I am going to borrow your LiPo pack/controller rack idea and price the Hyperion 1420 w/ ggoodrum bms. How many miles are you getting per charge on (8p) 40ah in hilly CA?

 

[Sacman]

Sacman, Thank you for sharing info. That is a nice build and clean charging system. I like the big apple 3.5” tires, too. I was budgeting for the Cyclops 2.4”s. I am going to borrow your LiPo pack/controller rack idea and price the Hyperion 1420 w/ ggoodrum bms. How many miles are you getting per charge on (8p) 40ah in hilly CA?

Thanks that 1-plug charging setup has been the best for me. That charging setup is a bit more expensive but I'm sure your father would be more at ease if you talked him into letting you build a balance/charge setup rather than just a bulk charge setup. The balance/charge is much safer and less likely to burn down your garage. :wink: :wink: :wink:

My 35-mile one-way commute to work only drains my battery pack down to 65%DOD while averaging 23mph. So maybe I can get out to 60 or 65 miles, even farther if i keep my speed down below 20mph.

 

[Sacman]

I have to correct the mis-information on my video.
Those are 2.35-inch Big Apple tires.

 

[e.s.dude]

I think I am going to mount my 12S 2P battery pack (4 X 6S, 5.0ah) on the front side of the down tube. (see photo 1)

I am going to build the battery pod out of 4 mil coroplast sheet.

Yard signs are made of this plastic (see photo 2).

It’s waterproof, light, strong and I can cut n shape it. (see photo 3)

 

[Sacman]

The 4 mil coroplast sheets sound good for protecive armor for your battery packs.
The real trick is making a structurally sound mount that holds your batteries securely to the bike frame.
Can't wait to see how you're gonna do that. :wink:

 

[e.s.dude]

Scratch that idea (see photo). I made four 6S 5.0ah zippy LiPo battery models to scale out of graph paper. I stuck them on the bike and discovered that I have no tire clearance.

Single file does not work either. The down tube is only 58cm and I need 67cm minimum to pull that off.

I am going to work on a triangle cover design (greyb.org style) that sticks out about 6-7cm on each side. That should give me enough clearance for several LiPos. I'll make it out of the coroplast sheets.

Sacman: I was going to use 1/4" plywood from the hobby store for support and mounting screws.

 

[Sacman]

Scratch that idea (see photo). I made four 6S 5.0ah zippy LiPo battery models to scale out of graph paper. I stuck them on the bike and discovered that I have no tire clearance.

Single file does not work either. The down tube is only 58mm and I need 67mm minimum to pull that off.

Good.... I hope you also noticed something more obvious... that you front suspension fork has about 1.5 to 2 inches (38mm to 50mm) of travel and if you hit a good bump your front tire would smash into your most forward batteries.

I am going to work on a triangle cover design (greyb.org style) that sticks out about 6-7mm on each side. That should give me enough clearance for several LiPos. I'll make it out of the coroplast sheets.

Sounds good but just looking at your scale battery models looks like it will be a challenge to fit just one battery brick in any of the opens triangle spaces of your bike frame. Unless you're talking about mounting the batteries perpendicular to the bike frame??? Hope I'm not sounding discouraging to you because I'm really not trying to be. Truth is I hope you succeed in finding a new and clever method to mounting those batts mid-frame because I eventually want to mount mine there someday too.

Sacman: I was going to use 1/4" plywood from the hobby store for support and mounting screws.

Dogman made battery boxes from plywood too and hung them saddle-style mid-frame on the toptube of his Mongoose. You might want to take a look at his to get some ideas. Only bad thing he mentions about it is that the boxes stick out wide such that he smacks them with his knees. So he has to pedal bow-legged or not pedal at all.
Heyena put his batts in a long rectanglular tube that he mounted longitudinal above the toptube. You might look into that too.

 

[e.s.dude]

Sacman: I’ll check those builds out.

I thought about using PVC sq. gutter pipe. Ace hardware has a 2.5” sq. pipe. (see photo). The LiPos would fit in a single file.

 

[teklektik]

Looks like I can switch the disc brake to the rear and the caliper brake to the front.
Anybody know the advantage of having the disc brake on front verses back wheel for a street bike?

Leave the disc in front - that's where you need the most braking power. In any case, you will get regen in the rear to assist your vbrake. See Sheldon Brown on Braking.

See this thread for thoughts about mounting your battery up front - sounds strange, but seems to be working out well: Cromotor vs 54xx - Fight! (discussion is in the middle of the build thread).

 

[e.s.dude]

Thanks tek... bookmarked