My first DIY e-bike, newbie alert

[fingret]

Hi

After browsing the web the last couple of days I decided I need some help.

So the thing is, I have no bike so I need to buy one. After that, I want to buy an e-bike kit from some chinese site. So before I buy a bike, I would like some ideas from you guys on what bike to buy. I will use the bike mainly for commuting to work and also for getting groceries with a bike trailer. So maybe 1 hour of biking each day. That also means during wintertime, when we have alot of snow from time to time. Speed is not that important to me, but I want a strong motor that can help me uphills with my groceries... BUT, Swedish laws forbid anything more powerful than 250w..

So, if someone could answer the following questions, it would be alot easier for me to find a bike...

1. V-brake or Disc-brake? Which one is preferrable?
2. Should I avoid pedal brake? Or foot brake, I dunno what its called :/
3. Can I still benefit from a DIY e-bike if I can only buy a 250w motor? (Need help climbing hills, remember)
4. Should I buy a bike with full suspension, hardtail or no suspension?
5. Front or back kit?

Lots of questions, I'm sorry but i'm lost in this e-bike jungle!

 

[Drunkskunk]

Welcome to the forum.

250w is certainly better than no help at all, although I have my own beliefs on those laws.

V brakes are fine for most bikes at speeds below 50kph. a 250w motor isn't likely to ever break 30kph, so V brakes will be all you need. Unless you're going to be riding through deep snow. Then you want disk or drum brakes.

The pedal brakes are called Coaster brakes here. those won't work with a rear motor, but would be OK with a front motor if you also had a front brake of some kind.

Non suspension bikes are the easiest to convert. Bikes like the Trek 800 are just about ideal. Often it makes more sense to buy a used bike.
For a front motor, you want something with a steel fork. for a rear motor, you want a bike with 7 gears and a conventional derailer. adding nice fat 2.35" to 2.5" tires will really improve the ride.

A third possibility is a motor that runs through the chain. there aren't many in the 250w range, but 250w motors won't help you up steep hills much. A motor like the Bafang BBS01, a 350w motor, will run through the bike's gears and let you gear down for hills, or gear up for speed. Its technically illegal, but as long as you use it responsibly, .. well, that's your moral dilemma to solve. It would work better for for your hills.

 

[fingret]

Welcome to the forum.

250w is certainly better than no help at all, although I have my own beliefs on those laws.

V brakes are fine for most bikes at speeds below 50kph. a 250w motor isn't likely to ever break 30kph, so V brakes will be all you need. Unless you're going to be riding through deep snow. Then you want disk or drum brakes.

The pedal brakes are called Coaster brakes here. those won't work with a rear motor, but would be OK with a front motor if you also had a front brake of some kind.

Non suspension bikes are the easiest to convert. Bikes like the Trek 800 are just about ideal. Often it makes more sense to buy a used bike.
For a front motor, you want something with a steel fork. for a rear motor, you want a bike with 7 gears and a conventional derailer. adding nice fat 2.35" to 2.5" tires will really improve the ride.

A third possibility is a motor that runs through the chain. there aren't many in the 250w range, but 250w motors won't help you up steep hills much. A motor like the Bafang BBS01, a 350w motor, will run through the bike's gears and let you gear down for hills, or gear up for speed. Its technically illegal, but as long as you use it responsibly, .. well, that's your moral dilemma to solve. It would work better for for your hills.

Thanks for your kind advice. I have been looking around for a bike and found a used Marin Pine Mountain, (steelfram) shown on this picture:

https://dl.dropboxusercontent.com/u/167524/3925088003.jpg

I think this will be quite good for an e-bike?

My main problem now is the PAS. I think I will be ordering my parts from em3ev but the kits does not include a PAS sensor. But I have a question about the PAS sensor itself. Does the PAS detect the pressure I put on the pedals? Or will the motor work 100% as soon as I start pedalling? I really want the motor to adjust power based on how hard I press the pedals.

Any of you guys with an advice in this matter?

 

[TotalConfusion]

My main problem now is the PAS. I think I will be ordering my parts from em3ev but the kits does not include a PAS sensor. But I have a question about the PAS sensor itself. Does the PAS detect the pressure I put on the pedals? Or will the motor work 100% as soon as I start pedalling? I really want the motor to adjust power based on how hard I press the pedals.

Any of you guys with an advice in this matter?

Paul sells both types of PAS sensors also, If you are buying a CAV3 then its this one http://em3ev.com/store/index.php?route=product/product&path=41&product_id=163

If its a stand alone system without a CAV3 use this one i think http://em3ev.com/store/index.php?route=product/product&path=41&product_id=104

If you talk to Paul regarding your set up he will advise you what is best for your system.

You can set the PAS up to help you at different levels of PAS when pedalling so it can help you out alot up a hill and then you can dial it back when your on the flats to save battery power.

I am no expert in PAS as i have never used it nor seen it set up but i have read some info on the workings around the system but im sure if im wrong someone with much greater knowledge will correct me and set you on a better path.

 

[fingret]

My main problem now is the PAS. I think I will be ordering my parts from em3ev but the kits does not include a PAS sensor. But I have a question about the PAS sensor itself. Does the PAS detect the pressure I put on the pedals? Or will the motor work 100% as soon as I start pedalling? I really want the motor to adjust power based on how hard I press the pedals.

Any of you guys with an advice in this matter?

Paul sells both types of PAS sensors also, If you are buying a CAV3 then its this one http://em3ev.com/store/index.php?route=product/product&path=41&product_id=163

If its a stand alone system without a CAV3 use this one i think http://em3ev.com/store/index.php?route=product/product&path=41&product_id=104

If you talk to Paul regarding your set up he will advise you what is best for your system.

You can set the PAS up to help you at different levels of PAS when pedalling so it can help you out alot up a hill and then you can dial it back when your on the flats to save battery power.

I am no expert in PAS as i have never used it nor seen it set up but i have read some info on the workings around the system but im sure if im wrong someone with much greater knowledge will correct me and set you on a better path.

I think I will order the CAV3. I think the PAS will not detect torque, which is a requirement if you wanna ride an ebike in Sweden. So maybe I need to replace my bottom bracket with a torque sensor bottom bracket... hmm...

 

[TotalConfusion]

http://www.ebikes.ca/shop/ebike-parts.html?p=6 sells TDCM Torque Sensing Bottom Bracket, CA3 Compatible

 

[d8veh]

Who told you that you need a torque sensor in Sweden? As far as I can find out, the regulations say that you have to pedal to get power, so a normal pedal speed sensor is sufficient.

Torque sensors bring unnecessary expense, weight and complication compared with any benefit they bring. Most modern controllers have a LCD, where you can set the level of power that you get when pedalling if using a pedal speed sensor.

When you're limited to 250w, the difference in price between a self-converted bike and a OEM one is very small, so it would be better to buy a ready-made bike from a shop.

Try and find a bike with disc brakes. They're so much better than rim brakes. Rim brakes are OK for light-weight bikes, but on an ebike you'll spend a lot of time adjusting them and replacing pads. Eventually, you'll have to replace a rim, which might be a problem if it's a motor-wheel.

Full suspension bikes can be more comfortable on long journeys. For short journeys and city riding, a hard-tail is easier.

 

[fingret]

Who told you that you need a torque sensor in Sweden? As far as I can find out, the regulations say that you have to pedal to get power, so a normal pedal speed sensor is sufficient.

The Swedish institute of transport has a few rules listed on their webpage, one of the rules are as follows:

"An electric bike counts as a bicycle only if the bike has a motor that is turned on when the pressure on the pedals increase, for example to make it easier to go uphill or when facing strong winds."

I interpret this as PAS aint sufficient, as it does not feel the pressure on the pedals.

Thank you for your other thoughts. But from what I've heard, ready made e-bikes do have kinda bad quality components (cheap ones) or they are VERY expensive. And the other thing involved is the actual fun of building something yourself, at least from my point of view

 

[ColinB]

Hi Fingret,
Lots of decisions!

1. V-brake or Disc-brake? Which one is preferrable?
- I'd go with disks. A bike heavy with motors, batteries and groceries can be hard to stop. My V-brakes are marginal.

2. Should I avoid pedal brake? Or foot brake, I dunno what its called.
- Yes. Because that means you won't have gears, and you'll want gears on hills!

3. Can I still benefit from a DIY e-bike if I can only buy a 250w motor? (Need help climbing hills, remember)
- Maybe. Could be more expensive. But then you get to pick components, repairs are easier, etc.

4. Should I buy a bike with full suspension, hardtail or no suspension?
- What do you like to ride? If not full suspension, at least ensure you have clearance for wide tires.

5. Front or back kit?
- Rear motor is good. I think the dropouts tend to be stronger?
- Rear motor can be bad - could change how your shifting operates. (ie. My motor can fit a 7 speed freewheel only. If you want to use a 9 speed cassette, you'd be out of luck.)

Trailer
- For 250 watts, I'd consider not going with a trailer. Anything to reduce drag and weight will really help at these power levels. Consider front and rear paniers maybe? Some of those panier bags are pretty big.

The 250 watt limit I think will be your biggest issue. Check out the motor simulator at http://www.ebikes.ca, and see what types/models might be ok at 250 watts. For reference, I've got the Cylte 3548 on 48 volts on my heavy recumbent. I try to see how little power I can get away with; it's fun, and kinder to my batteries. On hills that I'd be in my easiest gears, I can get up them at around 350-400 watts. I haven't tried 250. I think my motor would be a bit slow there. Most of the time on my ride I'm around 350-550 watts. If I increase the max power to 1000 watts, the motor really "wakes up" and puts that big e-bike grin on.

You could look at really small motors to save weight. http://www.ebikes.ca/shop/ebike-parts/motors/moutrider-std.html. I wish I had spent more effort in putting together a lighter kit. Or use a motor made for 26" wheels and lace it to a 20", if your bike uses a smaller wheel like the cargo bikes here: http://www.ebikes.ca/shop/edgerunner.html.

If your motor is capable of more than 250 watts but is limited by the controller or Cycle Analyst, is it still legal?

Hope this helps.
Colin

 

[riba2233]

http://www.eclipsebikes.com/chainwheel-watt-ebike-p-969.html

or

http://www.eclipsebikes.com/chainwheel-watt-ebike-p-975.html

It is 250w, but it pull's on uphill without problem, because it uses gears. I have it, and it is really good on the uphills. But you have to have some tools and knowledge to instal it, and pas works like shit, so don't use it. I doubt that police will give you a ticket for non using pas.

I now see that they have bafang mid drive, that's also a good option:

http://www.eclipsebikes.com/bafang-8fun-bbs01-drive-250w-motor-p-1102.html

But more expensive. I also see it has torque sensor, so that's a better option if you want pas.

 

[fingret]

Thanks again for great answers! What a great forum.

Now when I've read all your posts I'm actually thinking about buying a 350w+ anyway... Like someone said, I doubt the police will stop me and if they do, I bet they don't know the rules anyway. About the bike itself, I now have some guidelines. Will be fun to be part of the e-bike ppl

 

[fingret]

If your motor is capable of more than 250 watts but is limited by the controller or Cycle Analyst, is it still legal?

Thanks Colin for valuable input. The answer to this question is no. The Swedish laws are retarded and outdated.

Thank you riba2233 for your suggestion. After some research I found the Bafang-8fun-Bafun-BBS-01 from greenbikekit to be exactly what i'm looking for. I ordered the parts and hopefully I will get them the next week and after assembly I'll post here to let you know what I think about it.

 

[fingret]

What is the easiest possible solution to install a watt meter into the bbs01 system on my bike?

BBS01 36V350W and a LiFePO4 36V10AH bottle battery...

 

[Chalo]

1. V-brake or Disc-brake? Which one is preferrable?

Either kind can be very strong or very weak, or anything in between. V-brakes usually need more frequent attention, but discs are much more difficult to work on when they do need maintenance or repair. I'd go with V-brakes in most cases because they are so much less expensive.

2. Should I avoid pedal brake? Or foot brake, I dunno what its called :/

That's a coaster brake. There is no reason to avoid it, but it should not be your only brake, or even your primary brake. Of course, any wheel with a coaster brake can't also have a hub motor in it. You can get internal gear hubs of 3 to 9 speeds that have coaster brakes.

3. Can I still benefit from a DIY e-bike if I can only buy a 250w motor? (Need help climbing hills, remember)

250W will help, but it must be optimized to give useful torque at low road speed. If it's designed to deliver 250W at 35kph, then it will not help you much when you are going very slowly on a steep incline.

4. Should I buy a bike with full suspension, hardtail or no suspension?

At 250W speeds and on paved surfaces, suspension won't do anything for you but add cost, weight, maintenance, and points of failure. No suspension.

5. Front or back kit?

At 250W, it doesn't matter. Using a front motor means your rear wheel can keep its full strength (hub motor wheels are weaker than equally built normal bike wheels).