Best donor frame to build an electric bike & getting started

[Tommy L]

One must keep in mind that Rim Brakes are grabbing something that is turning slower than grabbing closer to the hub, which is turning much faster.

You've got that backwards. The RPMs would obviously be the same, but the surface feet per minute is much higher at the rim.

Just to add my 2¢ to the disc vs. rim brake debate, I personally would always take discs. If you're an all-weather rider, the wet performance is far superior. If you're a trail rider, the better modulation with discs helps a lot.
TRP Spyre/Spyke mechanical calipers are fantastic. I ditched all my hydraulics for them.

ooooops correct you are but the torque required to stop closer to the hub would be higher. Right?
I have the Juicy 3 Hydraulic. seems real nice, a little finger goes a long way.
I'll check the Mechanical Calipers that you mentioned! Thank you!

 

[Epyon]

ooooops correct you are but the torque required to stop closer to the hub would be higher. Right?

I'd assume yes, more leverage working against the rotor.

 

[barber111]

My "plan", is pretty basic BUT I'm hoping for STRONG..

Getting a '18 Bullseye Monster XX for the donor. Going with BBSHD mid. Most all my riding will be on dirt roads. I'm 6'6" and 250lbs.

1. fat tire bike in my size, under $1,000.00..
2. Hydraulic disc..
3. Threaded BB..

I'm excited to start..

Barber

 

[Bullfrog]

First, no offense taken by anyone that doesn't agree with me so feel free to express your opinions...I might learn something.

There was a discussion earlier on brakes and I came across something on the Luna Cycles site that I thought I should post since it isn't my opinion but info from one of the biggest ebike sellers around. For a donor bike, they recommend:

Consider spending more money on your donor bike. If you use cheap components and add high power, it can be a dangerous combination…things you might want to consider:

Disc brakes are a must…preferably high quality
Full suspension is cool but difficult to mount, plus battery and frame might flex
Consider a hardtail downhill bike…the most practical donor solution
Quality ebike tires are a must, preferably DOT speed rated
High quality derailleur and shifters are needed to survive with high power

Some more data...here is a statement for the renowned Sheldon Brown "For bicycles used on-road, the advantages of disc brakes aren't as compelling.". Just wanted to point out that disc brakes aren't always the best choice.

And if you are having trouble deciding what is best for your applications, read this well written article, although it is intended for Road Bikes, the information applies to all two wheelers: https://blog.performancebike.com/2015/01/06/road-bikes-rim-brakes-vs-disc-brakes/

OK now that I beat that dead horse again and again, back to the fun stuff....

I have just ordered a Mongoose Terrex (my third) and a Mongoose Hitch (my first fat bike). I will be changing forks and brakes on both bikes before I ride them with electric motors. The Terrex is going to be built to go do some downhill riding this summer at a ski resort. Plan to install a DNM-USD8 fork, 27.5x3.00 Maxxis High Roller in the rear and a 27.5x2.8 Maxxis DHF in the front. Brakes will be 203 mm in the rear and the largest the DNM is rated to allow in the front. I have a lot of off road miles on the two other Terrexs...one with a MAC and one with a BBSHD. No problems to date other than they aren't the lightest bikes around . Both come in right around 65 lbs with a 14s6p battery. I have Shimano hydraulic disc brakes with 203 mm rotors on the rear and 180 mm on the front. Only reason I didn't go 203 on the front is the XCR forks I am using are not rated for anything larger than 180. The XCR forks work fairly well...I'd rate them a best bang for the buck. You can get forks that are much better but they are going to cost a lot more too...my XCRs were $100-$125 each.

The new Hitch is going to either get a BBSHD or a Cyclone kit...still trying to decide. Tried to buy a Ludicrous controller from Luna and they turned me down. Seems you have to spend some big bucks (IMO) with them before you can buy the good parts and if I have to go to an external controller then the cleanliness of the BBSHD installation is compromised and the Cyclone starts to look more attractive.

Just wanted to provide a little update on my STEEL FRAMED, DISC BRAKE builds ....and yes I am a lot prejudice but that doesn't mean my choices are best for you. If you are having fun, nothing else matters.

 

[Bullfrog]

Here is a pic of my MAC powered Terrex:

 

[Bullfrog]

Warning Warning Warning...if you follow my recommendations for adding ATF to a MAC to keep it cool, eventually it will leak on the brake rotor and you will lose your back brakes.

As usual the wonderful people at Grin Tech are correct....they tried to warn me that the leakage would eventually become an issue but just like listening to my parents, professors, and friends...I had to prove it via experience. The good news is that adding 2.5-3.5 ounces of low viscosity ATF to your MAC will keep it cool with the max temps never going over approximately 85C.

The leakage didn't occur while riding on relatively smooth paved surfaces but over the last couple days I have ridden off road on some pretty rough ground with exposed roots and rocks...my guess is the rough surfaces caused the ATF to splash around inside the motor more, therefore it came in contact with the opening in the axle where the wiring exits...and eventually started to seep out of the left side of the axle and onto the brake disc.

A lot of good information in this thread...and I can tell you how NOT to cool an Internally Geared Hub (IGH) motor. For anyone riding off road at relatively slow speeds and needing high torque...my recommendation is to go with a Mid-Drive motor like the Bafang BBSHD because you can utilize the bikes gearing as well as the motors gearing to keep the motor spinning at an efficient rpm and produce less waste heat.

The next best option for slow speed/off road/high torque is a Hub motor with auxiliary cooling like Statorade, Forced Air, etc.

The last option I would choose is a IGH motor just because it is sooo difficult to cool. Mine works great when riding on the pavement at speeds where the motor is in an efficient rpm range but you have to choose the right tool for he job and I didn't when I chose an IGH motor for riding off road at relatively slow speeds with high torque requirements.

 

[The Mighty Volt]

I have a 12t MAC running in a 24" wheel and on a 6 fet controller of 16s Lipo hitting peaks of 60Amps and it doesn't get warm and the controller gets tepid after some hard ripping.

The TRP brakes are great. I have them.

I have a steel frame and I welded on my own torque arms too.

Even with my Mac in a 24" wheel I still see peaks of 4000w and its important to have your frame modified.

It's a shitty ebay steel frame.

 

[Bullfrog]

MAC is a great motor if used correctly....mine doesn't get warm when riding on the pavement at about 30 mph.

My problems occur when my 220 lbs + 70 lb bike are riding off road at 5 mph and I need to climb a long hill that requires full throttle for extended periods.

Slow speeds + hills + high torque + wide open throttle + 40 Amp controller and 14s battery = high temps.

 

[The Mighty Volt]

My motor never seems to get warm. Ok the last time I took it out there was snow on the road. But it didn't get warm after 4Ah up some good hills.

What I worry about is the effect of 4000w, in bursts.

But there is no heat yet.

The frame was an off-ebay, steel frame. I welded on some torque arms with a stick welder.

Most expensive doesn't mean best, always.

 

[Bullfrog]

Mighty Volt...something isn't quite matching up. If you are running a 6 FET controller then it is most likely limiting your amperage to 25 amps...that is the amperage limit on the 6 FET controllers I could find. If you are running a 16s battery then hot of the charger at 100% it should read about 67.2 volts. And 67.2 volts x 25 amps = 1680 watts...which is the maximum power that should be going to your motor with your components.

Don't get me wrong, that is a good set up and you shouldn't have too much of an overheating problem...the 24" wheel just helps even more. I agree with your comment 100%..."Most expensive doesn't mean best, always.". All of my bikes cost less than $200 each...of course I have upgraded a lot of components and that doesn't include any of the ebike stuff like motors, controllers, or batteries. I am a fond of the Mongoose Terrex and Hitch (Dolomite, Malus, Azted, etc) which are all steel framed and structurally over designed.

Sounds like you or somebody did a good job of putting the package together. Just FYI, I recently switched to a 20" rim (57mm internal width) and mounted a 4" wide Mongoose tire...lost a little ground clearance but it is working great, especially when I hit sand. I am running 8 psi and about six ounces of Orange Seal in the tube...never had a flat. If riding on the road, I pump it up to about 20 psi. A while back I swapped out the crank and crank arms for a set with 140mm crank arms...that helped a lot with pedal strikes but it makes pedaling feel pretty weird .

 

[Bullfrog]

Well the Mongoose Hitch is working great but I readily admit that in the long run most people will want to upgrade the components. The frame is rock solid and I have had absolutely no problems with the steel frame...below is a list of things I have changed and things that have stayed stock:

A. Frame...steel and working great. No cracks, bends, or problems anywhere.

B. Front fork...came with a rigid steel fork and I quickly upgraded to a Suntour XCR 29" fork. The 29 allows me to run a 27.5x2.8 Maxxis DHR tire on a standard Mongoose Terrex 27.5 (52mm internal width) rim that I ordered directly from Mongoose for less than $50 delivered to my door. I can not run a tire wider than 2.8" so if you want to run a wider tire you need to find another fork option. IMO the Suntour XCR is the least expensive fork that works decent...anything cheaper and you mine as well keep the rigid fork . The XCR isn't great but it works acceptably.

C. Brake discs...went to a 180mm front because that is the largest that the XCR fork is rated to use and a 203mm in the rear.

D. Brakes...Stock mechanical no name cable operated calipers are working pretty good but I'll admit they do require constant adjusted if you want decent performance. I'll start a seperate thread on how I keep them adjusted...just search "Adjusting Mechanical Disc Brakes" in a few days. One thing that helped a lot is I bought new lever assemblies that are entirely made of aluminum and are very rigid...the stock lever assemblies have a lot of plastic parts that flex a lot when you pull the lever. The lever assemblies would be the first thing to upgrade IMO and they make it where the mechanical cable operated disc brakes are acceptable.

E. Stem...went to a 32mm stem for quicker steering and love it.

F. Handlebars...picked up a set of used steel bars at the local shop for $10 that are 700mm wide and have a 3.5" rise with a slight aft sweep. They are unmarked so I can't give you a manufacturer or a part number. Bars are sort of a personal preference thing so it is up to you...the biggest thing I like is the rise because my old back doesn't bend like it used to and I can sit more upright.

G. Tires...boy I have been thru some tires trying to find something I like. Ended up with a Maxxis Minion DHR II 27.5x2.8 Plus (60 TPI) on the front and a Maxxis Minion FBR 26x4.0 (120 TPI, EXO) on the rear. I run 14 psi in the front and 8 psi in the rear. Just FYI 60 TPI is a tougher but less supple tire. It is also more puncture resistant than 120. The 120 TPI will give a more comfortable ride. The chord in a 60 TPI tire is larger in diameter than a 120 TPI tire but there are fewer chords in a 60 TPI tire. So it just depends on whether you want a stronger heavier tire or a lighter better riding tire when choosing between 60 TPI and 120 TPI.

H. Pedals, rear rim, spokes, hub, chain, and freewheel are stock.

I. Seat Post/Seat...seatpost is a Diamondback suspension seat post via Amazon and the seat is a comfort seat from Nashbar.

Tid bits....I am running tubes and I run Orange Seal in the tubes and I have never had a flat. 99% of the time I ride off road in tight trails with some deep sand and some relatively small hill climbs...I run a 30 tooth front sprocket and a 26 tooth rear and with a 14s battery my top speed is about 17 mph which works well in the woods and my Bafang BBSHD motor never gets hot.

Here is a pic of my Mongoose Hitch with the BBSHD. It works great and I have a lot of fun with it. If I am out riding for fun I ride the Hitch. If I want to go fast off road I ride the Terrex I built with a BBSHD. If I am riding on the road I use the Terrex with the MAC motor. They all work great and were fairly easy to get everything working the way I like it.

 

[MadRhino]

There is no best or, there might be a best for yourself, until you find better. Different builders have very different requirements. Riders are riding very different terrain, distances, conditions, speed... Best for one, may be the worst to another.

 

[Bullfrog]

There is no best or, there might be a best for yourself, until you find better. Different builders have very different requirements. Riders are riding very different terrain, distances, conditions, speed... Best for one, may be the worst to another.

Agree...BUT for getting started and building your first ebike, a steel framed Mongoose Terrex would be MY recommendation. It is strong, inexpensive, comes with disc brakes (that you might want to change but it will have the mounts) and will accept a rear hub and/or a mid drive motor. Is it the best bike for everybody...nope, only you can decide what is best for you.

If you want tires wider than about 3.25", the Mongoose Hitch, Dolomite, Aztec, etc. are going to be hard to beat for a starter bike but the frames aren't quite as rigid as a Terrex. Just FYI, my Hitch will accept a 26x4.8" Maxxis Minion FBR in case anybody is wondering...but I would recommend the 4.0 you just have to have the extra flotation.

All of my posts under this thread are so that others can learn from my mistakes .

 

[Bullfrog]

...but will I be able to go 50mph? :wink:

Heck yea. 50 mph is a piece of cake...right after I drive off a cliff .

Actually the MAC powered Terrex with the original 27.5" wheel and a 14s battery fully charged to 58.8v will do an honest 34 mph on flat ground with no wind and me laying almost horizontal. It puts out about 2,350 watts.

The BBSHD powered Hitch doesn't go quite as fast...it tops out about 28 mph. It only produces about 1,760 watts max.

The speeds above were GPS not off of the bike's display. A little downhill or tail wind will significantly increase the speed and a little uphill or headwind will decrease them.

If speed is what you are chasing...I'd suggest something safer than the bikes I mention in this thread.

 

[MadRhino]

There is no best or, there might be a best for yourself, until you find better. Different builders have very different requirements. Riders are riding very different terrain, distances, conditions, speed... Best for one, may be the worst to another.

Agree...BUT for getting started and building your first ebike, a steel framed Mongoose Terrex would be MY recommendation. It is strong, inexpensive, comes with disc brakes (that you might want to change but it will have the mounts) and will accept a rear hub and/or a mid drive motor. Is it the best bike for everybody...nope, only you can decide what is best for you.

If you want tires wider than about 3.25", the Mongoose Hitch, Dolomite, Aztec, etc. are going to be hard to beat for a starter bike but the frames aren't quite as rigid as a Terrex. Just FYI, my Hitch will accept a 26x4.8" Maxxis Minion FBR in case anybody is wondering...but I would recommend the 4.0 you just have to have the extra flotation.

All of my posts under this thread are so that others can learn from my mistakes .

So, you had built on frames that you were not satisfied with, and end up being satisfied with this one ?

Now think that another builder does start with your recommendation, and it does end up being for him, the same first mistake that you did experienced.

I started with a much better bike, yet it was only the begining of a series that led me to the frames that I am using now. If I wanted other builders to learn from my mistakes, I would’t go telling them the frame I am using now is the best for them. I would tell them to spend all the time needed to define their requirements with precision, and buy the best that they can afford to succeed.

 

[Bullfrog]

Please don't misunderstand my wording and intent....I just want to share what I did and if anyone would like to copy it or learn from it then great. If you want to do something totally different, that is up to you and fine with me.

The only mistake I feel like I made along the way was selecting a MAC motor for use in a bike that was intended for single track off road use...it can work but it will overheat if you are not careful. For off road use I would recommend a BBSHD and for riding on the road I would recommend an IGH like the MAC or a DD hub motor.

The Mongoose Terrex and the Mongoose Hitch bikes/frames have turned out wonderfully. The frames have had no issues whatsoever, are very strong, and stand up to everything I have thrown at them. You can always make improvements...the only limitation is time and money. If the title of this thread was the best donor frame...I would have selected a titanium custom frame with full suspension capability but it is about getting started and I still believe the Mongoose Terrex is the best choice for me and I highly recommend it to others and if you want a bike with tires wider than approximately 3.25", the Mongoose Hitch is the best choice for me and I highly recommend it for others for...getting started.

 

[MadRhino]

Yep, now we are getting into riding style and performance requirements. That is why it is not so easy to recommend a new builder, the frame and components that will suit his needs. Even building for ourselves, is not so easy to make the best choices. Building for others is another story, their story.

We have to know a rider, we have to find his riding style and experience, and we have to define his expectations. Then we have to guide him into compromises, to make sure of his priorities, before we can give him a receipt (frame and components) that will be reliable for him, that he will be safe and happy to ride.

 

[Bullfrog]

LATE BREAKING NEWS AND WHY NOT TO USE A FAT TIRE BIKE FRAME...well at least one with 190 mm Over Locknut Dimension (OLD)/ rear spacing.

I stick with my recommendation on the Mongoose Terrex for two main reasons....
1. The frame is steel and very strong.
2. Mongoose has been very helpful and wonderful to work with regarding replacement parts for any Mongoose bike I have purchased.

I bought a Mongoose Hitch Fat Tire bike which is virtually identical to a Dolomite, Aztec, Malus, etc. and after riding it a couple months I pulled the rear wheel off to install my new Maxxis FBR 26x4.8" tire and the rear axle was bent. Now I am not the littlest fella around (approximately 200 lbs) and I am not the easiest on my bikes but I don't remember doing anything that should have cause a problem.
I ride off road only and have ridden off of a few small drops...most less than one foot where erosion has washed the trail out.

This same issue would occur with any bike that had 190 mm OLD in the rear and it should be less prevalent as the width narrows. Just wanted to pass along this warning/info to help others. If you ride on the pavement, this probably won't every occur but if you ride off road and are ever required to stand up on the pedals due to the terrain roughness...it is possible. My description is just a relative measure of loading on the rear axle.

I have seen Fat Tire bikes with the rear OLD as narrow as 135 mm, 170 mm is probably the most common, a fair number with 190 mm, and a few above 190 mm.

Hopefully all the info above will help you with buying and/or building your next bike.

BULLFROG

 

[Bullfrog]

Just a little more info to support disc brakes...and this is not my opinion but from someone who selected rim brakes. He does say that rim brakes can be lighter and a little simple if you have to disassemble your bike to travel for example but otherwise disc are the way to go.

https://www.youtube.com/watch?v=t0RpRnUPs6k

In the big picture as long as you are happy and ride safely...go with whatever brakes you like the best but my personal choice is always going to be disc brakes :wink: .

 

[wturber]

Just a little more info to support disc brakes...and this is not my opinion but from someone who selected rim brakes. He does say that rim brakes can be lighter and a little simple if you have to disassemble your bike to travel for example but otherwise disc are the way to go.

https://www.youtube.com/watch?v=t0RpRnUPs6k

In the big picture as long as you are happy and ride safely...go with whatever brakes you like the best but my personal choice is always going to be disc brakes :wink: .

Just another series of opinions. But in this case related to a much different kind of bike than the typical electric bike. So the relevance diminishes.

But as your final comment suggests. Either will do if of a high quality and set up correctly.

 

[Bullfrog]

Rim Brakes vs Disc Brakes....heard and interesting comment from Calvin Jones the Park Tools Guru.

He mentioned that if you can see any clearance when you lay a straight edge on a rim that uses rim brakes then it is time to replace it.

Whether you like rim brakes or disc brakes...one advantage of disc brakes is you don't wear your rims out from braking so they won't need replacing unless you damage them by other means :lol: .

A little more info...

Rim Brake Advantages:
Rim brakes are lighter than disc brakes — often as much as a pound.
Rim brakes are more aerodynamic than disc brakes.
Rim brakes are easier to repair.
Rim brakes cost less.

Disc Brake Advantages:
Disc brakes offer greater stopping power, which can be helpful on long descents.
Disc brakes don’t heat the rim, which has been known to cause tire blowouts on long descents when rim brakes are used.
Disc brakes allow for more precise braking, making wheel lockup less likely.
Disc brakes work better than rim brakes in wet weather.
Changing rotor sizes allows you to adjust how much braking power you want.
It’s easier to use wider tires with disc brakes.

Reference: https://blog.mapmyrun.com/rim-versus-disc-brake-debate-explained/

Regardless of which kind of brakes you prefer...please be sure they are in proper working order since ebikes can result in faster speeds which means braking is even more important.

 

[miro13car]

You forgot
Rim breaks wear rims, make rims weaker, wall thinner.
People seem to forget about it
I would rather replace disc on disc break than to replace rim with all this wheel building.

 

[Bullfrog]

Thanks Micro13...you have to sort of read between the lines with my comment on the straight edge...I should have been clearer why the straight edge test is used :wink: . I readily admit I am very prejudice toward disc brakes but there are some people who prefer rim brakes...in reality they both have advantages and disadvantages.

I personally would never ride any bike (ebike or pedal only) over about 20 mph with rim brakes or in wet conditions at any speed with rim brakes but I have realized over the years that just because I do something, it doesn't mean everybody feels the same way.

 

[dogman dan]

Steel frames are a plus for making a cheap first e bike for sure. Find an old Trek 820 for fifty bucks and you are golden. They tend to be stiffer than cheap alu frames. I'm talking about walbike, bike shaped object class alu frames, they suck. The cheapest steel bikes tend to suck to pedal because of weight, but motorized, the weight effect vanishes.

Also, if you get more advanced later, a steel frame can easily get modified with a welder, such as adding a welded on rack, or disc mounts.

For city riding, its hard to beat the steel 7 speed beach cruisers. Cheap, sturdier than some steel mtb frames, and come with welded on steel rear racks, and fenders can be very nice if you really commute in all weather.

Stuff like the Huffy Margaritaville, Kent bayside, etc. Anything with the extra middle bar in the frame for strength, two rim brakes, and 7 speed rear wheel. Slap a cheap 48v rear DD on it and off you go.

Upgrades can be easy, with parts from junk piles. A 1970 Schwinn varsity has a 52 tooth front chainring, that bolts right to a 2019 Schwinn cruiser. Wheel upgrades easy, good front wheels easy to find off of junked mtb's.

My cruiser started as a hundred bucks new Schwinn from Walmart. The first modification was welding on a disc mount to the front fork. The 7 speed derailleur just bolts on to a coaster brake cruiser, but with those, you have to put some kind of brakes on it if you replace the rear wheel. So I just advise looking for two rim brakes as a starting point.

 

[Balmorhea]

Rim breaks wear rims, make rims weaker, wall thinner.
People seem to forget about it
I would rather replace disc on disc break than to replace rim with all this wheel building.

Remember that disc brake wheels are weaker than rim brake wheels of otherwise equal construction. They have less spoke bracing angle, and the front wheels are dished.

How much wear you get out of a rim varies a lot depending on the pads used, weather conditions when riding, and local soil conditions. In the Pacific Northwest, it's common for year round riders to wear out a pair of rims every year, but where I am in Texas, rims can last for decades.

Discs are convenient when you want to use an unintended wheel size, as we e-bikers often do. And they're great for bikes with really fat tires. But as brakes, they don't offer anything you can't get from rim brakes with less cost, less weight, less vulnerability to damage, and easier maintenance.