My First Ebike Build Cromotor Lyen Mongoose Beast Fatbike

nerve

nerve

1 W
Joined
Apr 7, 2013
Messages
62
Location
Northeast USofA
Mongoose Beast with Cromotor and Lyen 18FET
80mm in the rear double wall
65mm in the front double wall
Sturmey archer X-FD Drum Brake...Regen in the rear...

I'm sill working on a kickstand solution and I'm looking for a better seat, head light on the way, and I need to tailor fit the 1000D Cordura frame wrap. On a full charge the CA says 37kph...

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So far it has been great. I took it off road, on the beach, and around town...good stuff so far!
 
Looks like you have a kickstand mount. Go to crow cycles and get a double stand from them. Mine's standing up to the frankenbike longtail, so it's STRONG.
 
Thanks Dogman! Will do... I think I'm gonna rock this little 36V battery for the summer. I had some pretty horrific and expensive bike accidents in my youth and I have not rode daily in 15yrs. Hopefully the battery technology will develop by the time I upgrade... :wink:

I made it up the steepest hill in my little village today, no problem. At the end of my ride yesterday, the battery cut out on a small but very steep hill, then it was completely dead about 5mins later. I'm still learning how to read my CA but I think I did 23kilometers on a full charge.
 
dogman said:
Looks like you have a kickstand mount. Go to crow cycles and get a double stand from them. Mine's standing up to the frankenbike longtail, so it's STRONG.
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I use a similar one (Sunlite) to keep my top-heavy lead sled vertical with excellent results. 8)
P.S. You might need to experiment with several different ones to find the best one for your particular bike. :wink:
 
It http://endless-sphere.com/forums/viewtopic.php?f=5&t=48316 seems that many people feel that suspension is worthwhile and some feel it is important. You mentioned you were looking for a new seat, while this wouldn't cover you on the seat, it would certainly aid you in ride comfort. http://www.amazon.com/gp/product/B003NE5IRK/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B003NE5IRK&linkCode=as2&tag=xbnijgbr-20&linkId=VLD7IHWBJI4U4BP6
It was suggested in that suspension thread. Congratulations on the ebike.
 
You're pulling 77A on a 15Ah battery? What's the C rating of those LiFePO4 cells?
 
Bike is doing great....

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I have the gearing at 36T/16T. With this gearing, I can pedal with the motor if i'm under <15mph. Over 15mph and the pedaling does nothing. Top speed of 25mph is perfect around town. If I want to go to the next town over, 35mph would be safer IMHO. My range needs to double if I want to drive the bike to my local off-road trails, if not, I got to load the bike in the truck and drive to the site. My lower back is a bit sore from two potholes I hit last week. Bowlofsalad, I thought of that thudbuster! Unfortunately, I have added a bent-back seat post which made the bike fit perfect for me.
I will be looking for a way to add suspension to my seat post. The salt air has already taken affect on my rear spokes and outer cromotor metal. see pic:
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All the other metal on the bike still looks like new. Not sure how bad this is?

If I do add another battery it would be for range not speed. My current throttle is either max-on or off. If I add a 24v battery and wire in series, that would bump me up to 60v? Could I get more range if I kept the max speed at 25mph in the CA at 60v? or do I have to wire in parallel with the same 36V to get more range? I ask because I'd like to only add the battery for certain trips, when needed, and I could use a 24v battery to power other stuff when not on the bike...
 
nerve said:
The salt air has already taken affect on my rear spokes and outer cromotor metal. [...] All the other metal on the bike still looks like new. Not sure how bad this is?
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Those spokes are crap. However, if they don't break, and they stay tight, then they'll do. If you replace them, do yourself a favor and use 14ga or 13/14ga spokes from a quality manufacturer like DT Swiss or Sapim.

I'd use some kind of spray coating like Boeshield T-9 or even WD-40 on the rusty motor parts, to keep the corrosion from getting bad enough to cause real problems later.

Why are you using such small knobbies on that bike? If you used something like the Surly Endomorph, you'd have better traction and lower rolling resistance on pavement, and you'd have enough ground clearance that you wouldn't need a small child's cranks. I understand that the Beast even accommodates the 26 x 4.7" Surly Big Fat Larry tire.

The point of a fatbike is fat tires, after all.

I have some concerns about your brakes. One normal diameter drum isn't really enough for that bike in my opinion, and I don't see the sort of torque arms that would make regen braking a reasonably safe proposition. Do you even have torque arms? Are you satisfied with your drum braking?
 
These rear spokes are 10ga. I personally would not use 14ga with a CroMotor.

The 135mm SINZ cranks are racing cranks not child's cranks. And the drive side pedal mount failed on me so I switched back to the 170mm steel cranks.
I currently have a 2.5" tire on the front rim and a 2.7" on the rear. The original Beast rims are not double walled and appeared to be the weak point of the Beast. My front rim is 65mm and the rear rim is 80mm. I'll try the endomorph tires...

I use the Doctor Bass Torque arms, which are the best solution IMHO.

I use regen 90% of the time and the front hub brake only on steep hills and for fast stops. The front hub brake is 100mm and works out perfect with the regen.
 
nerve said:
These rear spokes are 10ga. I personally would not use 14ga with a CroMotor.
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You'd need washers under the spoke heads if the holes are huge, but 14ga spokes are more reliable than thicker ones-- they stay tight at tensions that are tolerable for bicycle rims. Leg muscles can make more torque than your Cromotor (I just demonstrated to Hillhater that leg power can result in 270 lbs-ft of torque at the wheel-- more than enough to flip the bike). It is only in power output, and not force, where the electric motor excels.

The 135mm SINZ cranks are racing cranks not child's cranks.
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Yes they are-- they are designed for mini BMX racers-- meaning five- to seven-year-olds-- and that is why they are so short. If you use pedal power for more than cosmetic reasons, you'll be glad you switched back to 170mm cranks. My own 170mm cranks are kid-sized as far as I am concerned; I use them to accommodate low bottom brackets on old touring bikes. When I have the clearance for the, I use cranks from 205 to 225mm. My legs are long though, with a 40" standing inseam.

I use the Doctor Bass Torque arms, which are the best solution IMHO.
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Gluing things that could be mechanically fastened in never the best solution. It would be a good idea to drill, tap, and bolt through your "Dr." Bass torque arms, because no mechanical Ph.D. I have ever known would use glue to do a screw's job. That's redneck engineering for sure.

I use regen 90% of the time and the front hub brake only on steep hills and for fast stops. The front hub brake is 100mm and works out perfect with the regen.
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That's good as long as your e-braking is reliable enough to depend on. I don't have a better solution to suggest that would attach directly to the Beast without modification, except perhaps one of the new badass Shimano Rollerbrakes. The improvement those could offer would probably not be worth the cost of building a new wheel, though. I think you made a good compromise for your particular situation.
 
Chalo said:
You'd need washers under the spoke heads if the holes are huge, but 14ga spokes are more reliable than thicker ones-- they stay tight at tensions that are tolerable for bicycle rims. Leg muscles can make more torque than your Cromotor (I just demonstrated to Hillhater that leg power can result in 270 lbs-ft of torque at the wheel-- more than enough to flip the bike). It is only in power output, and not force, where the electric motor excels.
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What about weight?

Yes they are-- they are designed for mini BMX racers-- meaning five- to seven-year-olds-- and that is why they are so short. If you use pedal power for more than cosmetic reasons, you'll be glad you switched back to 170mm cranks.
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lol, I am.

Gluing things that could be mechanically fastened in never the best solution. It would be a good idea to drill, tap, and bolt through your "Dr." Bass torque arms, because no mechanical Ph.D. I have ever known would use glue to do a screw's job. That's redneck engineering for sure.
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Innovation Abound! I had my doubts about the DP420 at first, but having worked with it, I now believe it will hold up on its own. I will definitely post back here the day it fails.

That's good as long as your e-braking is reliable enough to depend on. I don't have a better solution to suggest that would attach directly to the Beast without modification, except perhaps one of the new badass Shimano Rollerbrakes. The improvement those could offer would probably not be worth the cost of building a new wheel, though. I think you made a good compromise for your particular situation.
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Thanks. Just to be safe, I will disconnect the ebraking and make sure the drumbrake holds up on its own should the e-brake fail.
 
Toorbough ULL-Zeveigh said:
Chalo said:
no mechanical Ph.D. I have ever known would use glue to do a screw's job. That's redneck engineering for sure.
Click to expand...

B-58 Hustler

bonded outer and inner aluminum skins to a honeycomb of aluminum and fiberglass
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us navy ssn buncha redneck engineers too.
Lotus, aston martin, list goes on.
now you now, "mr. aerospace".
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There was a lot of glued stuff, including carbon/Kevlar honeycomb, in the spacecraft I worked on. But if a part could be mechanically fastened, it was. That's the same for Boeing aircraft and everything else of the kind. If you're dealing with composites or paper-thin sheet materials, you bond them because you have to. If you're dealing with thick chunks of structural metals, you fasten them-- if you're not a nincompoop. The folks at Boeing rivet the aluminum skins of their aircraft. Don't you think they'd just use JB weld or Gorilla Glue or wheat paste if that worked best?

I said "glue to do a screw's job", not "glue to do a glue's job". Attaching a piece of 8mm aluminum plate to a piece of 10mm steel plate is a screw's job. Unless you're a nincompoop, that is.
 
nerve said:
These rear spokes are 10ga. I personally would not use 14ga with a CroMotor.
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14 gauge spokes would make a more reliable wheel than 10 gauge. Likewise, 14 gauge spokes butted to 15 gauge in the middle would make a much more reliable wheel, however if I were in your place I would run a triple butted spoke 13-15-14 gauge (to fill the inner hole on the cromotor spoke flange, going to a 15 gauge shank to give the spoke the ability to distribute stresses to the rim over as wide of area as possible when loaded (because they stretch more for a given amount of rim deformation), followed by a 14 gauge threaded portion.

Straight gauge on a spoke is always universally every time with no exceptions the more failure prone option than a butted spoke.
 
Chalo said:
Toorbough ULL-Zeveigh said:
Chalo said:
no mechanical Ph.D. I have ever known would use glue to do a screw's job. That's redneck engineering for sure.
Click to expand...

B-58 Hustler

bonded outer and inner aluminum skins to a honeycomb of aluminum and fiberglass
Click to expand...

us navy ssn buncha redneck engineers too.
Lotus, aston martin, list goes on.
now you know, "mr. aerospace".
Click to expand...

There was a lot of glued stuff, including carbon/Kevlar honeycomb, in the spacecraft I worked on. But if a part could be mechanically fastened, it was. That's the same for Boeing aircraft and everything else of the kind. If you're dealing with composites or paper-thin sheet materials, you bond them because you have to. If you're dealing with thick chunks of structural metals, you fasten them-- if you're not a nincompoop. The folks at Boeing rivet the aluminum skins of their aircraft. Don't you think they'd just use JB weld or Gorilla Glue or wheat paste if that worked best?

I said "glue to do a screw's job", not "glue to do a glue's job". Attaching a piece of 8mm aluminum plate to a piece of 10mm steel plate is a screw's job. Unless you're a nincompoop, that is.
Click to expand...


dunno man, may not be 8mm thick Alu sheet, could be in spots.
but it def aint paper thin to be sure.

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bunch of nincompoops said:
Bonding rather than welding or riveting, as chassis element joining method is preferred by engineering
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http://www.sandsmuseum.com/cars/elise/thecar/chassis/

want moa?
 
Do the engineers at Lotus glue on their brakes? Do they glue on their transmissions? No, they do not. That is the sort of thing we're talking about. And it is a dumb way to fasten a safety-critical item that has plenty of thickness to accept screws.
 
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