I currently own a trek fx 7.3 and want to convert. I want to have the ability to reach 40mph when i need it but not constant. I'd also like to get 30 mile range as well. Im aware DH bikes are a better option for this type of performance but this being my first build i would like to work with what i got. This bike should also have such performance without worries of overheating or any mechanical problems. I've done some research but dont have much knowledge about ebikes. So far i've noticed the cromotor is something i should consider along with lipo batteries. Im also aware i may have to modify the bike itself but can you guys help on what do i need exactly in order to achieve this type of performance while having a solid bike?
Im a noob and i wanna go 40mph
- Thread starter ftanka0
- Start date
First, I recommend reading all the various builds similar to what you want to do. Many discussions of this type of thing are included (some as links) in the 10MPH+ namesake of your thread. 
Drunkskunk
100 GW
Welcome to the forum.
We don't sugar coat things here. So lets start at the begining.
Wrong motor, wrong bike, wrong battery, wrong expectations.
That Trek fx 7.3 would be good for a bike capable of 25mph using a 500w motor. To go faster sustained, you would need to do some upgrading or become street pizza.
The Cromotor is a race motor. It evolved from chinese race motorcycles, and isn't something you can just slap on a bicycle and expect it to work. It would promptly turn that bike frame into a pretzel. If you want to run that motor, expect to drop a minimum of $5000 on your bike build. Its also a total waste on a bike you only want to go 40 with.
And Lipo is the battery equivalent of nitroglycerin. Its not "safe" and should only be used by people with experiance and then only on a bike that has need for a smaller package than LiFePO4. A123 cells can deliver the amperage An extreme bike needs safer than Lipo.
I would suggest doing a lot more reading on the forum. Not just what people have done with their bikes, but why they did those things.
We don't sugar coat things here. So lets start at the begining.
Wrong motor, wrong bike, wrong battery, wrong expectations.
That Trek fx 7.3 would be good for a bike capable of 25mph using a 500w motor. To go faster sustained, you would need to do some upgrading or become street pizza.
The Cromotor is a race motor. It evolved from chinese race motorcycles, and isn't something you can just slap on a bicycle and expect it to work. It would promptly turn that bike frame into a pretzel. If you want to run that motor, expect to drop a minimum of $5000 on your bike build. Its also a total waste on a bike you only want to go 40 with.
And Lipo is the battery equivalent of nitroglycerin. Its not "safe" and should only be used by people with experiance and then only on a bike that has need for a smaller package than LiFePO4. A123 cells can deliver the amperage An extreme bike needs safer than Lipo.
I would suggest doing a lot more reading on the forum. Not just what people have done with their bikes, but why they did those things.
sacko
10 kW
http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=42162
It will pull you up any hill, and top out at 28mph on the flat (44.4v lipo).
I used 44.4v 15ah, which would allow me to reach 30 miles range.
Giant XTC SE 21" frame
Hydraulic Disk Brakes
Schwalbe Big Apple 26x2.15"
EV Falcon Frame Bag
KU123 controller
Bafang 36v 500w Code 12
Twist throttle
For 40mph, I would look at a Magic Pie 2, a Greentime 72v controller and a handful of lipos.
It will pull you up any hill, and top out at 28mph on the flat (44.4v lipo).
I used 44.4v 15ah, which would allow me to reach 30 miles range.
Giant XTC SE 21" frame
Hydraulic Disk Brakes
Schwalbe Big Apple 26x2.15"
EV Falcon Frame Bag
KU123 controller
Bafang 36v 500w Code 12
Twist throttle
For 40mph, I would look at a Magic Pie 2, a Greentime 72v controller and a handful of lipos.
amberwolf, I've read similar builds and also the 50mph thread but I've also read the requirements for 50mph is much different from 40mph. That's why i wonder what upgrades my bike would need...
drunkskunk, when you say upgrading, do i need to upgrade to another bike or upgrade bike parts? my reason for considering cromotor is because since its so powerful, i would not have to worry about stressing and overheating when im going uphills at 30-40mph. I dont want a ebike that just meets my requirements but instead a bike that i can rely on to perform without feeling abused. And lastly, I've read about lipos dangers but also the ways to avoid the problems. If cromotor and lipo is too much then, can i do 40mph and about 30-40miles mostly at 30mph on a crystalyte hs3540 with A123 cells?
Sacko, thanks for your setup. Since when you've been using your ride?
drunkskunk, when you say upgrading, do i need to upgrade to another bike or upgrade bike parts? my reason for considering cromotor is because since its so powerful, i would not have to worry about stressing and overheating when im going uphills at 30-40mph. I dont want a ebike that just meets my requirements but instead a bike that i can rely on to perform without feeling abused. And lastly, I've read about lipos dangers but also the ways to avoid the problems. If cromotor and lipo is too much then, can i do 40mph and about 30-40miles mostly at 30mph on a crystalyte hs3540 with A123 cells?
Sacko, thanks for your setup. Since when you've been using your ride?
sacko
10 kW
Since July 2012.
I would also consider a magic pie 2;
http://www.goldenmotor.com/
..and a 72v controller
http://www.aliexpress.com/item/72V-1500W-Brushless-Speed-Controller-for-Electric-Bikes-High-Quality-OT100/287758466.html
..with lipos.
I would also consider a magic pie 2;
http://www.goldenmotor.com/
..and a 72v controller
http://www.aliexpress.com/item/72V-1500W-Brushless-Speed-Controller-for-Electric-Bikes-High-Quality-OT100/287758466.html
..with lipos.
Rodney64
100 kW
I have a FX 3 flat bar road bike and fitted a 500 watt kit with a Panasonic tube battery. Top speed 20 mph. I agree that this is the maximum you would want to push this frame. I've removed the kit now and not sure if I have any photos but will post one If I find one. I used it to commute to work 23km each way and then charged at work.
This frame at 40 mph is at the frames limit. Try riding it down a hill at 40. Very easy to loose control unless you have ridden road bikes and can ride them well. I am the first to admit that yes I can ride a road bike but have never been good at it. It's a good frame for 25 if your not confident on this bike.
Yes if you want to go 40 then you need a new frame.
I have a Norco aLine but the issue it there's not a lot of room for batteries. Look for a down hill frame with a big triangle, I've been looking but they're hard to come by. Kona stinky has a big triangle as an example.
Edit: Down hill frames most have a 10mm though axle on the rear. You'll need to get a frame with removable axle housing. This way you will be able to engineer 10 ml dropouts for the hub motor.
This frame at 40 mph is at the frames limit. Try riding it down a hill at 40. Very easy to loose control unless you have ridden road bikes and can ride them well. I am the first to admit that yes I can ride a road bike but have never been good at it. It's a good frame for 25 if your not confident on this bike.
Yes if you want to go 40 then you need a new frame.
I have a Norco aLine but the issue it there's not a lot of room for batteries. Look for a down hill frame with a big triangle, I've been looking but they're hard to come by. Kona stinky has a big triangle as an example.
Edit: Down hill frames most have a 10mm though axle on the rear. You'll need to get a frame with removable axle housing. This way you will be able to engineer 10 ml dropouts for the hub motor.
dogman dan
1 PW
Yes wrong bike for that kind of build.
Sure, I bet you've hit 40 mph going downhill on it and it felt fine. Now go strap 30 pounds of batteries and 20 pounds of motor on it, and try it again. You won't like the handling at 40 mph now!!!
It would be a good bike to motorize for different expectations, 10 pounds of motor and 8 pounds of battery, and not always using the motor for example. Top speed perhaps 30 mph.
Full suspension isn't mandatory for 40 mph, but it sure is advisable when you can't swerve around that pohole or manhole cover in time going that fast. My race bike is pretty sketchy if I street ride it with all the road defects.
Less motor could work for you, depending on the durations of the 40 mph riding. The crystalyte HS model would cruise at 30 mph nearly indefinitely on the flat, and should hit 40 mph or more on 72v. For 30 miles range AT 30 mph, you'd need about 20-25 ah of battery.
As for overheating and mechanical problems, well, asking for motorcycle performance from bicycles is at the very least asking for spoke and rim problems. But 30 mph cruise doesn't usually overheat a decent direct drive motor. The smaller dd's like 9 continent and similar other brands can take 40 mph for limited durations. So as long as you don't want 15 miles at 40 mph you generally are ok. But they do heat up fast with even short runs at 40mph. Properly done vent holes in the cover help a lot, so the heat doesn't stay trapped inside.
And since I always say this, in the USA most states would call your proposed bike illegal to ride on the street. Illegal as in faster than 20 mph is one thing, illegal as in noticeable as hell going 40 mph is another. I take my race bike out on the street, and everybody I see is doing this
when they see me.
Sure, I bet you've hit 40 mph going downhill on it and it felt fine. Now go strap 30 pounds of batteries and 20 pounds of motor on it, and try it again. You won't like the handling at 40 mph now!!!
It would be a good bike to motorize for different expectations, 10 pounds of motor and 8 pounds of battery, and not always using the motor for example. Top speed perhaps 30 mph.
Full suspension isn't mandatory for 40 mph, but it sure is advisable when you can't swerve around that pohole or manhole cover in time going that fast. My race bike is pretty sketchy if I street ride it with all the road defects.
Less motor could work for you, depending on the durations of the 40 mph riding. The crystalyte HS model would cruise at 30 mph nearly indefinitely on the flat, and should hit 40 mph or more on 72v. For 30 miles range AT 30 mph, you'd need about 20-25 ah of battery.
As for overheating and mechanical problems, well, asking for motorcycle performance from bicycles is at the very least asking for spoke and rim problems. But 30 mph cruise doesn't usually overheat a decent direct drive motor. The smaller dd's like 9 continent and similar other brands can take 40 mph for limited durations. So as long as you don't want 15 miles at 40 mph you generally are ok. But they do heat up fast with even short runs at 40mph. Properly done vent holes in the cover help a lot, so the heat doesn't stay trapped inside.
And since I always say this, in the USA most states would call your proposed bike illegal to ride on the street. Illegal as in faster than 20 mph is one thing, illegal as in noticeable as hell going 40 mph is another. I take my race bike out on the street, and everybody I see is doing this
when they see me.
wesnewell
100 GW
Here you go. See sig line for major parts. Added wide riser handlebars and CST Cyclops 2.4 tires for control and stability. Fabricated battery holder from old aluminum yard sign. Big saddle for comfort. Windshield not shown for aerodynamics optional. Total cost with all options about $1000. Add $100 for charger setup.
OK, so im convinced on not using my trek for this setup. Since im on a tight budget, what do you guys think of the walmart full suspension bikes? ei. mongoose xr-pro 29er or xr-200 or genesis brand
As for motor, I read enough on crystalyte so x5 series will be my first choice if not the the h series works as well but more limited.
how do you guys feel about big box bikes? can they be modified for high performance?
As for motor, I read enough on crystalyte so x5 series will be my first choice if not the the h series works as well but more limited.
how do you guys feel about big box bikes? can they be modified for high performance?
geeeyejo1
1 kW
I would scour your local Craigslist for a used Cromo Steel Framed Mountain Bike - I picked up my 90's Gary Fisher that originally retailed for $700+ for only $150 - rock solid frame, relatively light and decent front suspension - way better than what $150 would buy new at Walmart/Target/Etc.ftanka0 said:
With that said, I have heard that the Genesis bike from Walmart is a pretty good value on a full suspension bike for $160?
I'm not a bike frame expert, but personally I think you'd be better off modifying your Trek; it's probably a lot higher quality frame/components than most wallyworld-type bikes.ftanka0 said:
That said, my CrazyBike2 is built from a pretty decent 70s/80s Schwinn in back, and crappy 90s(?) Magna in front, and it took over 4000 miles of heavy abuse as a cargo hauler to finally break the frame of the Schwinn, and only then because of the way I designed it and put it together. Magna part has never broken. However, the Magna part of it is wiggly/twisty under some conditions, and worse the faster I go (and I typically only go up to 20MPH, but have been up to maybe 35MPH once on the straight at the kart track in Tucson, but also had a geometry issue at that time, made worse by the wiggliness of the Magna).
So, YMMV. If I had the budget for it, and were going to build a fast bicycle for city road use using only bicycle parts, I'd be using much better parts, figuring to spend $2000-$3000 just on the bicycle bits if I got them used. But in reality with my extreme budget limitations I'd probably be building it from scratch (or from other bike frames or even motorcycle frame parts), and I'd probably be using MC or moped shocks and wheels, because those are a lot cheaper than similar-usage-rating bicycle parts, and can often be had for very little on Craigslist (sometimes for nothing on Freecycle). But it is a lot of work...I have such a project in the works that may never be finished at this point.
wesnewell
100 GW
http://www.amazon.com/Serfas-Super-Cruiser-Bicycle-Saddle/dp/B000MT0ICO/ref=sr_1_19
The only other saddle that I can ride for any distance is the Worksman
http://www.drillspot.com/products/490508/worksman_cycles_6911v_extra_wide_bicycle_seat
Not sure which I prefer. The Serfas is more springy, but the Worksman seems more solid.
The only other saddle that I can ride for any distance is the Worksman
http://www.drillspot.com/products/490508/worksman_cycles_6911v_extra_wide_bicycle_seat
Not sure which I prefer. The Serfas is more springy, but the Worksman seems more solid.
