Best donor frame to build an electric bike & getting started

General Discussion about electric bicycles.
Bullfrog
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Best donor frame to build an electric bike & getting started

Post by Bullfrog » Nov 01, 2017 10:15 am

So you want to build an electric bike...have you lost your mind? It is a lot of work and is going to cost a lot of money. The fully assembled bikes like the ones that Luna Cycles sells and the Radrover are something you should consider before you read any further.

Haven't changed your mind...well my recommendation is a steel frame because it is stronger than aluminum and steel will bend before it breaks more than aluminum so it gives you a visual warning that it is about to let go. Carbon...forget it, one second it is fine and the next it is broken, strong yes...up until it breaks without any warning whatsoever. The drawback, a steel frame can be a little heavier.

Instead of suggesting what to buy, I'll tell you what I did...I was in your shoes a about a year ago and I couldn't find the information below.

I spent about a gazillion hours scouring the internet and researching every bike in the world. I came to the conclusion that a Mongoose Terrex was the way to go. Now I'll agree that most Big Box Store (Walmart, Kmart, Sears, Academy, etc) bikes aren't worth taking out of the box but I found a pretty good one...the Terrex. I couldn't get any image to post so here is a link to the Walmart site with the Terex: https://www.walmart.com/ip/27-5-Mongoos ... e/45146057

More data and info on the Terrex....

I bought my second Mongoose Terrex recently and it turns out the newest ones have a 148 mm OLD. The first one I bought has a 140 mm OLD. OLD is "Over Locknut Dimension" and is what is commonly known as the "spacing". The numbers I gave are for the rear. That is the only difference I can find between the two bikes....and the rear hubs which match the frame OLD.

The first Terrex I bought has a 12T MAC hub motor. It works great on the road but I have had some issues when riding off road really hard. I ride off road about 95% of the time and climb some reasonable hills but slow speed and hill climbing at the same time are a worst case scenario for overheating. I have a 20" x 57 mm internal width rim ordered which will be laced to a MAC housing and I plan to do some experiments with ATF to see how much it helps cool the MAC. Plan on mounting a 4" wide tire on the rim...that should give me a little cushion on the rear of the Terrex since it is a hardtail. I am running a Cycle Analyst Version 3 which is commonly abbreviated CAv3....with a MAC motor that has temp sensors like the one I bought from EM3ev, the CAv3 will tell you what the temp of the motor is and roll back the power if it gets too hot to keep you from damaging anything.

A plug for Grin Technologies....these guys are the sharpest around. They sell the CA (all versions) and a battery charger called the Satiator. The Satiator is a little pricey at around $300 but you can program it to charge just about any battery and you can set it to charge just about any voltage profile you want. If you don't know already, Lithium batteries can be a little finicky and it is a challenge to keep them happy. The power output can be amazing but to make them last as long as possible you don't want to get them too hot, too cold, charge them too high or run them too low. Sort of like Goldilocks....treat them just right and they are as wonderful as a fairly tale. Grin also has a motor simulator and a charge simulator that are worth investigating.

Forks....well I had asked about upgrading forks and never got a response so I ventured out on my own. Keep in mind everything I post is my opinion so yours may be different but the best coil spring fork I could find, that fits the Terrex is the Suntour XCR. I went with a 29" XCR fork because I am running a 27.5+ tire and the 29" has the largest crown to axle distance. The XCR is also a 1 1/8" steerer tube with no taper, 135 mm OLD, a steel as opposed to aluminum steerer, and has a rebound adjustment (on some versions...choose carefully). The widest tire I can run with the 29" XCR fork is 2.8". Currently running a Maxxis DHF 27.5 x 2.8". The stock forks are only good for a paperweight....I have tried everything including disassembling them and greasing them with grease and silicone (separately) and they still stick terribley...it is called stiction, plus the springs are way too stiff for me. Why coil springs instead of air springs...I want to ride and not be checking or adjusting my forks. The coils don't change...the air shouldn't but it can be affected by temperature and leakage. Air forks are lighter and should give you higher performance but remember on the Terrex you need a 1 1/8 steerer that isn't tapered and most air forks, well most forks in general are now 1 1/2 on the bottom and 1 1/8 on the top i.e. tapered. The tapered design is better and "Problem Solver" makes an adapter where you can run the tapered forks but it gets complicated since it significantly affects the steering geometry.

The widest tire I can run on the rear of the Terrex (both OLD versions) is a 3.0"...currently running a Maxxis High Roller 27.5 x 3.0.

The second Terrex has a Bafang BBSHD and has worked nicely. I did "customize" the Freewheel (cassette) so that my chain line was close to perfect but otherwise the only change is the XCR fork and tires. I am also running a 30T Mighty Mini gear (from Luna Cycles) on the BBSHD...highly recommended if you want your motor to stay cool and operate at its most efficient rpm. Off road I run the 29 tooth or 34 tooth rear sprocket depending on how tight the trails are and almost never shift gears. The freewheel has a 24 tooth I use for getting from A to B.

I weigh 220 lbs ready to ride and I am running 13 psi front and rear. For me it is the optimum pressure to add cushion or suspension via the tires without the tires rolling over and affecting the handling. Also, any lower and when I hit a root the rim strikes the root and I'll eventually bend a rim.

Recently purchased a Mongoose Hitch Fat Tire bike and the Terrex appears to have a slightly stronger frame. The only reason I bought the Hitch was to run a wider rear tire and see if I could get enough cushion/suspension with the Fat Tire in the rear to keep my old arthritic back from hurting. I plan to run a XCR fork on it with the 27.5 x 2.8 DHF front tire because I hate how a Fat Tire bike steers, especially as you drop the pressure in the front tire. It is called "Self Steer" and the bike has a mind of its own. If that doesn't work, the next step is a full suspension and starting from scratch again...lots of options, although a Giant Reign would be my tentative starting point. The cost of any good full suspension bike is going to be more than either one of the complete set ups I am currently riding so cost is going to more than double. The biggest problem is most full suspension bikes have aluminum or carbon frames...remember our discussion earlier?

Just FYI, the cost to build a Mongoose Terrex with a MAC or a BBSHD is approximately $1,500 if you shop carefully and squeeze your pennies tightly. Roughly....Bike $250, motor kit $700, battery $500. Oh yea batteries....I am running a 14s6p 52v nominal battery. 14s means 14 batteries in series and 6p means 6 parallel strings of 14. The "s" determines the voltage i.e. how fast you can get there and the "p" correlates with the capacity i.e. how far you can go. I'd very highly recommend a 52v battery as opposed to a 48v or lower if you can afford it. You can't go over 60v with the BBSHD and the 52v fully charged is 58.8v. The higher voltage will give the motor a higher speed and you'll be able to feel the 52v is a little snappier than the 48v.

Whatever you choose....your motor, your controller, your battery, and the way you are going to use the bike need to be somewhat matched. Doesn't do any good to have a 30A controller if your battery will only supply 10A. Off road, the BBSHD is the way to go because you can use the gears to spin the motor at an efficient rpm. On the road or commuting, I'd lean towards the MAC because the power doesn't go thru your bikes chain/drivetrain...unless you live in a pretty hilly area then I'd go back to the BBSHD for the hill climbing capability. Want to go fast...you need voltage and a Direct Drive (DD) motor like the Crystalyte or the MXUS or even the Cromotor if you really want to scream. I have no need for the DD motors...they have their application but don't match the way I ride.

There are a lot of other options besides the Bafang BBSHD and the MAC but they are the two most common and cover at least 90% of the needs out there. Of those 90%, the MAC probably covers 40% and the BBSHD the other 60%. So if you do the multiplication, the MAC covers 36%, the BBSHD 54%, and other motors cover the remaining 10%...just my estimate, no specific data utilized.

Everything above is just my opinion....what do I know I am just a Mechanical Engineer with over 50 years of experience. That basically means I have screwed up enough times to know what I am doing now....sort of.

Now go back and read the first line of this post. There are a bunch of good options besides what I listed, those are just a couple good ones. If you still want to go thru the pain and suffering of building your own bike...Walmart will deliver the Terrex to your door.

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Re: Best donor frame to build an electric bike & getting sta

Post by skyungjae » Nov 01, 2017 10:27 am

...but will I be able to go 50mph? :wink:
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Re: Best donor frame to build an electric bike & getting sta

Post by tanstaafl » Nov 01, 2017 11:21 am

I'm sure a lot of people here will consider this a heresy, but I recommend getting started with cheap ebay kit. That's how I started.

Don't get me wrong -- over the course of the past year I have replaced every single component that came in that kit. Every one. But, my initial investment was low. I learned a lot before I had a ton of money invested. I got to find out first hand if an ebike was really for me. And I have a full stock of spare parts that I can use while a better replacement is on order -- just in case anything breaks. And while none of the cheap kit parts was particularly _good_, none of them were particularly _bad_ either. They were almost good enough, or good enough that I didn't need to replace them but just wanted to.

My original ebike cost was an extremely low $250 or so. This is including the bike, $35 on clearance from Walmart. The kit was around $150 from ebay. The battery (not part of the kit) was an awful homemade SLA that I put together from UPS batteries that I got from an office supply store's reward program. It worked. It had enough power to get me from home to work and back (9AH, 48V).

The only part of the whole thing I regret buying is the cheap bike from Walmart. I would have been much better off getting a cheap craigslist bike. But I didn't know enough about what I would need to make a good decision until after I saw all the stuff I didn't like about the Walmart bike. Over the course of a couple months riding (about 500 miles) I spent several times the cost of the original bike on replacement parts for things that didn't hold up well. I've heard the Walmart bicycles described as "bike shaped objects" and I think that's a pretty fair description.

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Re: Best donor frame to build an electric bike & getting sta

Post by JDMopar » Nov 01, 2017 12:44 pm

Most of your advice I'm on board with, except for buying a Walmart bike. I'm sorry but personally I don't think that's ever a good idea *ducks the rocks*. As a bicycle mechanic with 8 years experience, I can say without doubt that quality control on those bikes is awful, they are made from heavy poor quality steel, have absurdly heavy wheels, and their components are no better. That said, if you REALLY want 3" tires and rudimentary suspension, well then I can't suggest any better and I will cede to your judgement. But...

My advice to every person who has less than $200 to spend on a bike is to buy a used Trek or Specialized or yes even a Mongoose! But instead of a new bike, look for a 20+ year old steel framed, cantilever or v- brakes, gently used mountain bike. Shop carefully and you'll easily be able to find a really nice one for <$100 (originally $400-$500) and it will be of much superior quality to a new Walmart bike. It will need a tune-up and probably a few new parts but it will be lighter and work much better than a Walmart bike. I've worked on hundreds of those old bikes and they are a joy because after a couple cables and maybe new tires, they work just fantastic. I hate working on Walmart bikes. I can get them to work but the bearings are never as nice and shifting never as crisp.

Either that or start with a quality new frame/bike as OP says in his first sentence which is excellent advice.

But, I guess take my words with a grain of salt and if you really want 3 inch tires and [rudimentary] suspension, then the OP has it right.

Edit: really sorry if I come across as offensive but I am very opinionated on this subject. One of my favorite things ever was to repair an old mountain bike and to witness the reaction of people who never thought their old forgotten cobwebbed bike could work so well. Much worse is repairing a brand new Walmart bike and telling the customer that it was missing a brake pad from the factory and, shifter cables were kinked and needed replacing, and all bearings we're loose or way overtight.

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Re: Best donor frame to build an electric bike & getting sta

Post by Raisedeyebrows » Nov 01, 2017 1:12 pm

Just one suggestion.

Old Specialized Hard Rock steel frame, rides good, nearly bombproof, can pick them up for pennies on the dollar in good "were hardly ever ridden" shape oftentimes. I put a cheapo 9C clone motor on one, a pair of Kool-stops and scared up a decent set of used suspension forks for it. Rides good, looks good, smells good, chicks dig it. Feels like it won't fall apart, inspires confidence.

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Re: Best donor frame to build an electric bike & getting sta

Post by Bullfrog » Nov 01, 2017 8:49 pm

For anyone that doesn't like the Terrex....I have one question.

Have you personally touched a current production Mongoose Terrex and looked at the quality of the welds and the construction of the bike? If not you should retract your criticism until you do. If you have and you don't like the Terrex that is OK, we are just going to have to agree to disagree. For $224 you are not going to find a new bike anywhere close...IMO.

I have bent, broken, and worn out a lot of bikes in my life and "most" big box store bikes aren't worth taking out of the box....like I said in my very first post but IMO the current Terrex is a pretty good bike, very strong, and is going to probably last longer than I will. The fork needs to be replaced and I have replaced the tires because I ride in slippery mud and needed something more aggressive but other than that the components are decent...not good mind you but they are usable. How many big box store bikes come with a 180 mm front disc....that is just one example of how the Terrex is different from most of the bikes in Walmart and other big box stores.

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Re: Best donor frame to build an electric bike & getting sta

Post by JDMopar » Nov 01, 2017 8:53 pm

Raisedeyebrows wrote:Just one suggestion.

Old Specialized Hard Rock steel frame, rides good, nearly bombproof, can pick them up for pennies on the dollar in good "were hardly ever ridden" shape oftentimes. I put a cheapo 9C clone motor on one, a pair of Kool-stops and scared up a decent set of used suspension forks for it. Rides good, looks good, smells good, chicks dig it. Feels like it won't fall apart, inspires confidence.
Ya really can't do much better than this. If I didn't already own an old spare KHS frame to build up then I probably should have done precisely this...and come to think of it, it still would have been a better use of my money. :lol: What I'm building has better components, but bang for the buck even including some great deals I got on components, it is certainly not close to your setup.

My brother owns an old Cannondale aluminum road bike CAAD2 I think. I freakin love that thing. Agile, stiff, not a creak anywhere. It had downtube shifters and bomproof Shimano RSX and I converted it to 9-speed Tiagra for better hill gearing and safety, simply by bolting on a 9-speed freehub body and redishing the rear wheel. Only thing is I can't do the racer position, so I don't like it so much after 5 miles...perhaps a flat/slight rise stem and new bars and I would enjoy it.

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Re: Best donor frame to build an electric bike & getting sta

Post by JDMopar » Nov 01, 2017 9:09 pm

Bullfrog wrote:For anyone that doesn't like the Terrex....I have one question.

Have you personally touched a current production Mongoose Terrex and looked at the quality of the welds and the construction of the bike? If not you should retract your criticism until you do. If you have and you don't like the Terrex that is OK, we are just going to have to agree to disagree. For $224 you are not going to find a new bike anywhere close...IMO.
Fair. It's possible, but then it would be the only Walmart bike that's ever impressed me, and I've worked on hundreds. But either way I'd probably agree with the bolded.
Bullfrog wrote: I have bent, broken, and worn out a lot of bikes in my life and "most" big box store bikes aren't worth taking out of the box....like I said in my very first post but IMO the current Terrex is a pretty good bike, very strong, and is going to probably last longer than I will. The fork needs to be replaced and I have replaced the tires because I ride in slippery mud and needed something more aggressive but other than that the components are decent...not good mind you but they are usable. How many big box store bikes come with a 180 mm front disc....that is just one example of how the Terrex is different from most of the bikes in Walmart and other big box stores.
I can't tell the disc brake brand on that Terrex but I will say that even on ~$500 new bikes optioned with mechanical discs are rarely superior to $500 new bikes optioned with v-brakes, regardless of rotor size. Low-end mechanical discs just flat suck, the stand-outs being Avid BB7s (really more mid-range), and Shimano mechanical (still not awesome but decent). This is something I've noticed with Specialized, Giant, Jamis, Cannondale...so I'm not knocking the Terrex brakes itself but I personally would choose rim brakes over disc if I were to buy a bike under $500. Working in a shop (not on commission, ha) I would tell people exactly that if they asked, even though we make a little more money on disc-optioned bikes-but truly those sold themselves because disc brakes are an attention-getter.

That's if all other things are equal...and of course I know that's rim brakes are not an option with the 3 inch tires on the Terrex.

You've got some other good advice above, so I'll stop now, and withhold any further judgement until I have a chance to look at a Mongoose Terrex.

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Re: Best donor frame to build an electric bike & getting sta

Post by wturber » Nov 01, 2017 9:30 pm

My recommendation is much simpler. Find an example of someone who has already successfully done what you would like to do and then pretty much copy what they did. Simple. :^)

As someone else mentioned, you'll probably end up changing lots of stuff anyway. Often not because you really need to, but because now with some riding under your belt, you better understand what is important to you. This approach gives you a great chance at initial success and will present minimal frustration. You can always learn the intimate details of all the whys and why-nots afterwards as you muse on building your next bike. Meanwhile you can continue to enjoy the bike you didn't wait six months or a year to build.
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Re: Best donor frame to build an electric bike & getting sta

Post by tanstaafl » Nov 01, 2017 9:38 pm

Bullfrog wrote:For anyone that doesn't like the Terrex....I have one question.

Have you personally touched a current production Mongoose Terrex and looked at the quality of the welds and the construction of the bike? If not you should retract your criticism until you do. If you have and you don't like the Terrex that is OK, we are just going to have to agree to disagree. For $224 you are not going to find a new bike anywhere close...IMO...
Found this earlier thread and it does sound nice: https://endless-sphere.com/forums/viewt ... =3&t=72910
I'm sure you can find good bargains on bikes, even at Walmart on occasion. I'm pretty happy with my bike that I got for about $60 less from Nashbar, too. The only thing it's lacking is disc brakes, which the Terrex has. I'm not thrilled with the particular brakes on my bike and I may upgrade them, but I don't know that cheap disc brakes would be any better than cheap rim brakes. And I'm not saying the Terrex has cheap rim brakes, since I've not actually tried them.

One big complaint about Walmart bikes is still going to hold true for the Terrex, though. They are often poorly assembled and adjusted -- there's no consistency. In fact, some of them have been absolutely horrible. If you're building your own ebike, though, I guess you can probably fix this yourself. I'd just urge anybody buying one to check everything. The one I bought was pretty badly assembled.
Last edited by tanstaafl on Nov 01, 2017 9:45 pm, edited 1 time in total.

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Re: Best donor frame to build an electric bike & getting sta

Post by Bullfrog » Nov 01, 2017 9:39 pm

JD....the Terrex IS the only Walmart bike that has ever impressed me.

And somebody mentioned older bikes....agree 100% if you go with a used bike. Older bikes are in general better built. The mass production and drive to make a few bucks has affected the quality of bikes...in a negative way.

The brakes on the Terrex are "no name" cable operated calipers and discs...180 mm rear and 160 mm front. As far as disc brakes go they are pretty low quality. Personally I'd rather have any working disc brake than I would any type that clamps on the rim's surface. Sort of like comparing the drum brakes in my '70 Falcon (they pushed on a rim) to the disc brakes on any vehicle today. The "clamp on the rim" brakes are lighter and have less inertia (no rotor to spin up) so in some applications like lightweight road bikes they have a place....but when it comes to stopping, you aren't going to beat a disc.

Any brake that clamps on the rim is a similar design to drum brakes in a car....you wouldn't purposefully look for a car with drum brakes would you?

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Re: Best donor frame to build an electric bike & getting sta

Post by tanstaafl » Nov 01, 2017 9:54 pm

Bullfrog wrote:...

Any brake that clamps on the rim is a similar design to drum brakes in a car....you wouldn't purposefully look for a car with drum brakes would you?
Don't go there. :) Disc vs. rim is practically a religious argument. And it's not nearly so clear-cut as you would claim. There are fine arguments to be made on both sides. For my touring bike (Surly LHT) I think the rim brakes are just about perfect, for example.

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Re: Best donor frame to build an electric bike & getting sta

Post by Tommy L » Nov 01, 2017 10:25 pm

Cool Read!

For the average person ...... a prebuilt might be the way to go......

I've been doing this for 8 years and love it!

Built a Lawn Tractor with ME motor and 2kw LiFePO4 pack
Built a Pusher Trailer with VFD and AC motor
Built a Catrike with Bionx and made a Velomobile cover for it
Built my 50mph off road FS bike (just switch from Lifepo4 to Muiltistars)

Just finished my wifes bike: Bafang BBs02 with the Shark 18650 48v pack and color screen. She Loves it. She's had two strokes and is in heart failure. Has a pacemaker/Defibrillator now, but this build allows her
to go out for a ride and make it home if she starts to get tired. I go away a lot, so this is a nice plug and play. It's got a BMS on the 18650's .... but man, not knowing what the cells are up to would drive me insane!

I'm looking for a donor bike to do a Bafang BBs02 or the HD, but I will use multistars and monitor them ;)
I was looking for 6061 aluminum frames, but I guess steel is better at showing fatigue if fatigue happens...

I'm looking at doing a FatBike.... I hear that these two are decent donors:

The Gravity Monster Fat bikes at Bikes direct.

But I don't know nothing.

I've dumped over 7Kw into my 9C 2810 DD and it still runs today! (it's 7 years old)
But I run High Voltages like 144v.... and it's a 10 turn windings ;)
On an Aluminum FS Frame with Steel Swing arm.

The build thread is in my signature block... Still ride this bike today with 24S 10ah MultiStars. 100.8 volts :)

But I'm still looking for the ultimate Donor bike..... I'd like to put my Cells in the frame instead of my backpack! lol

Tommy L sends........
http://www.rawvelocity.com

- 4th Hoolagan FS Mtn 9C-2810 with 128v nom 9.2ah A123 40S40P(1.2Kw) - Lyen 18Fet 4115 - 77.8kph :)
https://endless-sphere.com/forums/viewto ... =4&t=39480

- 3rd Catrike 700 Bionx PL350 Velo build
http://www.youtube.com/watch?v=rYdnkaAhVtI

- 2nd 150lbs Pusher Trailer
http://www.youtube.com/watch?v=Q1qTc4sjORY

- 1st Sears NS mtn bike - Rigid 10a drill 800rpm - 2 12v AGM - 1000 watt inverter - 600w dimmer for throttle, wicked torque!

48.2mph/77.8kph Club

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Tommy L
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Re: Best donor frame to build an electric bike & getting sta

Post by Tommy L » Nov 01, 2017 10:31 pm

my Juicy Hydraulic on the front is nice..... but my rear still has the Rim brake and it works very well.

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.
Apparently, Rim brakes will out perform a cheap disc brake system. And you now know why ;)

But again..... I don't know anything.... :)
http://www.rawvelocity.com

- 4th Hoolagan FS Mtn 9C-2810 with 128v nom 9.2ah A123 40S40P(1.2Kw) - Lyen 18Fet 4115 - 77.8kph :)
https://endless-sphere.com/forums/viewto ... =4&t=39480

- 3rd Catrike 700 Bionx PL350 Velo build
http://www.youtube.com/watch?v=rYdnkaAhVtI

- 2nd 150lbs Pusher Trailer
http://www.youtube.com/watch?v=Q1qTc4sjORY

- 1st Sears NS mtn bike - Rigid 10a drill 800rpm - 2 12v AGM - 1000 watt inverter - 600w dimmer for throttle, wicked torque!

48.2mph/77.8kph Club

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Tommy L
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Re: Best donor frame to build an electric bike & getting sta

Post by Tommy L » Nov 01, 2017 10:38 pm

Properly designed brakes to the job very well.

That would include a properly engineered Drum Brake. Some appearance of better performance of rear Disc brakes with calipers maybe because of design and weight of a vehicle.
You may also be fooled into it being better because of a newer model cars proportioning valve may allow for more percentage to the rear calipers making the illusion that you have
more stopping power to the rear.

Many factor come into play. Remember, there maybe some variable that isn't known or seen ;)

Tommy L sends.....
Last edited by Tommy L on Nov 01, 2017 10:49 pm, edited 1 time in total.
http://www.rawvelocity.com

- 4th Hoolagan FS Mtn 9C-2810 with 128v nom 9.2ah A123 40S40P(1.2Kw) - Lyen 18Fet 4115 - 77.8kph :)
https://endless-sphere.com/forums/viewto ... =4&t=39480

- 3rd Catrike 700 Bionx PL350 Velo build
http://www.youtube.com/watch?v=rYdnkaAhVtI

- 2nd 150lbs Pusher Trailer
http://www.youtube.com/watch?v=Q1qTc4sjORY

- 1st Sears NS mtn bike - Rigid 10a drill 800rpm - 2 12v AGM - 1000 watt inverter - 600w dimmer for throttle, wicked torque!

48.2mph/77.8kph Club

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Tommy L
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Re: Best donor frame to build an electric bike & getting sta

Post by Tommy L » Nov 01, 2017 10:46 pm

This is a very informative video on Proportion Valve

http://www.rawvelocity.com

- 4th Hoolagan FS Mtn 9C-2810 with 128v nom 9.2ah A123 40S40P(1.2Kw) - Lyen 18Fet 4115 - 77.8kph :)
https://endless-sphere.com/forums/viewto ... =4&t=39480

- 3rd Catrike 700 Bionx PL350 Velo build
http://www.youtube.com/watch?v=rYdnkaAhVtI

- 2nd 150lbs Pusher Trailer
http://www.youtube.com/watch?v=Q1qTc4sjORY

- 1st Sears NS mtn bike - Rigid 10a drill 800rpm - 2 12v AGM - 1000 watt inverter - 600w dimmer for throttle, wicked torque!

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Re: Best donor frame to build an electric bike & getting sta

Post by Raisedeyebrows » Nov 01, 2017 11:14 pm

I'll have to give one of those Terrex fatties a quick look the next time I end up at a Walmart. My wifey's ride is an old Moongoose MTB from the days when they were sold in bike shops. It's light, it rides good, it's held up well over the years, only thing I've changed out are the grips, pads, tires and several tubes.

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Re: Best donor frame to build an electric bike & getting sta

Post by wturber » Nov 02, 2017 3:13 am

Bullfrog wrote:
Any brake that clamps on the rim is a similar design to drum brakes in a car....you wouldn't purposefully look for a car with drum brakes would you?
Without getting into the religious debates over which kind of brake is best, I'd like to point out thar rim brakes are actually a kind of disc brake, not a kind of drum brake.
Last edited by wturber on Nov 02, 2017 11:48 am, edited 1 time in total.
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Re: Best donor frame to build an electric bike & getting sta

Post by Bullfrog » Nov 02, 2017 6:48 am

Yea I guess your are correct about rim brakes being a type of disc.

I was thinking more about the pressure per square inch the pads apply.

Here is a good article that covers the advantages and disadvantages of disc brakes better than I ever could.

https://www.sheldonbrown.com/disc-brakes.html

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Re: Best donor frame to build an electric bike & getting sta

Post by Wolfeman » Nov 02, 2017 8:23 am

I'll chime in here. I've only built (assembled from a kit) one ebike, but it's taught me a lot. For a first timer I would recommend any good steel frame donor bike, an eBay 48V 1000W rear wheel kit, a Luna built 48V or 52V battery and good charger. This gives you a great starter bike that will last for many miles. It also allows you to slowly upgrade things as you advance.
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Re: Best donor frame to build an electric bike & getting sta

Post by wturber » Nov 02, 2017 11:54 am

Bullfrog wrote:
I was thinking more about the pressure per square inch the pads apply.
... and perhaps ignoring the greater mechanical advantage they have by virtue of being closer to the full diameter of the wheel ( so they don't need as much pressure), and the great mass a rim has for absorbing heat and greater surface area for radiating it.

Each type of brake has its pros and cons. It just isn't the simple slam dunk your previous post suggests. It is more of a "horses for courses" and personal preference issue. Both can work very well for an e-bike. It just depends ...
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
7 x 36v 4.3ah 10s 2P battery packs - Wangdd22 1500W 30A DC Boost Converter delivers 54v and about 1175 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
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Re: Best donor frame to build an electric bike & getting sta

Post by Tommy L » Nov 02, 2017 12:20 pm

wturber wrote:
Bullfrog wrote:
I was thinking more about the pressure per square inch the pads apply.
Each type of brake has its pros and cons. It just isn't the simple slam dunk your previous post suggests. It is more of a "horses for courses" and personal preference issue. Both can work very well for an e-bike. It just depends ...

Not only does each brake have a pro or con...... the quality and design of each is a huge factor. Example.... a good quality Rim Brake design/components may well be WAY better than a poorly designed Disc Brake system. And the reverse would also hold very true. There is quality and junk. ;)
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Re: Best donor frame to build an electric bike & getting sta

Post by wturber » Nov 02, 2017 3:42 pm

Tommy L wrote:
wturber wrote:
Bullfrog wrote:
I was thinking more about the pressure per square inch the pads apply.
Each type of brake has its pros and cons. It just isn't the simple slam dunk your previous post suggests. It is more of a "horses for courses" and personal preference issue. Both can work very well for an e-bike. It just depends ...

Not only does each brake have a pro or con...... the quality and design of each is a huge factor. Example.... a good quality Rim Brake design/components may well be WAY better than a poorly designed Disc Brake system. And the reverse would also hold very true. There is quality and junk. ;)
Yeah. Good point. And the quality of the brake shoes and or pads can be huge factor as well.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
7 x 36v 4.3ah 10s 2P battery packs - Wangdd22 1500W 30A DC Boost Converter delivers 54v and about 1175 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
https://endless-sphere.com/forums/viewt ... =2&t=90369

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Re: Best donor frame to build an electric bike & getting sta

Post by Toorbough ULL-Zeveigh » Nov 02, 2017 9:31 pm

Lotus :mrgreen:
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Kick down the barricades Listen what the kids say.
From time to time people change their minds But the Frock is here to stay.
I've seen it all from the bottom to the top Everywhere I go the kids wanna Frock.
Around the world or around the block Everywhere I go the kids wanna Frock.

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Re: Best donor frame to build an electric bike & getting sta

Post by Epyon » Nov 03, 2017 1:20 am

Tommy L wrote: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.

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