e-road-bike advice please

[hoo]

I want a roadbike which i can pedal most of the time, but that has some electric power-- to enable me to ride further distances, help up hills etc, and allow me to ride from A to B without turning up covered in sweat if i need.

So i am looking at 200-250W. I'd like it to be as discrete, and light, as is practicle. I'm not sure about battery size, but i may well start out quite small to see if that suits me.
I'd like to be able to take it off-road ocassionally-- on paths and such.

If I was looking at getting just a pedal-powered bike, i'd be willing to spend £2-300 to get a decent, used road bike, or cyclocross bike. But how much of the bike's quality would be lost with a conversion?? (eg. would it not be worth getting anything better than a decade+ old al. road bike?)
And which parts are made less/more important with an electric conversion?

AFAICT i'm looking at a rear, geared hub motor. What about the gears-- would it just be the rear freewheel that the hub-motored wheel replaced; ie. would it be compatible with the rest of the chain/gearing system?
Is there a chain-driven system that is actually worth considering??

I'd like to start looking for the bike now (to ride pedal powered until i am finalised on all the electric parts), so i'd really appreciate the advice. It's so difficult with such little overlap between the road bike and ebike worlds!

 

[dogman dan]

A rear gearmotor is a good compromise choice for many who want what you want. It's a compromise, because at the lightest it may still add a whopping ten pounds to the bike. Some find that too much weight to pedal around unpowered. But the internal gearmotors at least have a freewheel so you don't have to pedal through the motor resistance when not under power.

This gets a bit confusing at first for some. With the motor installed, you'll actually have two freewheels back there. One inside the motor will allow the wheel to turn even if the motor is not turning. Then attached to the motor will be a regular screw on 5-7 speed freewheel gear cluster. So no rear motor with a IGH rear wheel, but it will work with all chain and derailur systems up to 7 speed. You can press it and still use an 8 speed shifter, but by 9 speed the indexing is too far off to be really usable.

So your ideal bike is typicaly a fairly cheap steel frame with 7 speeds in the rear.

Be ready for it, you'll find riding using the motor so nice, you won't want to stop. So you'll end up wanting a fairly large and heavy battery if you ride longer distances.

 

[Geebee]

Probably the wrong forum for discrete easily pedalled bike with assist
Having said that if you go for a front wheel hub (Cute motor?) and intend to pedal a fair bit you should be able to get away with an all up weight of 2.5 to 3 kg.
I just fitted a rear motor to my recumbent trike and when the new Lipo batteries arrive all up e assist should be just over 3 kg or and barely visible.
The ideal motor would be a Tongxin but they are no longer available (and can be fragile) but my freewheel causes much more drag than the hub.

A rear motor will be heavier and limit your gear selection. and a front drive will be easy and quick to swap out if you want to.
Frame wise stick to aluminium or Cromo, aluminium will require a torque arm for safety, Cormo won't at those wattages.

 

[amigafan2003]

Are you looking to do something like this?

All in weight of 17kg, 20mph unassisted, 20 mile range, Tongxin front hub, 44.4v of 10ah lipo.

build log here:- http://www.pedelecs.co.uk/forum/electric-bicycles/9442-new-build.html

 

[gestalt]

So far from what I've seen on this forum the eBoost also known as the Kepler drive is the slickest way to transform a road bike while maintaining all of what we love about our light and nimble street whips. It's basically a self engaging/disengaging friction drive that uses the tiny rc outrunner motor as the roller itself. Whenever you're not using the assist it disengages from the rear tire right below your seatpost. Very very lightweight. I don't know if they are still available but it would be worth asking Kepler about it.

 

[Drunkskunk]

You will need a geared hub motor, probably a front motor so you can retain all of the rear gearing. Hub motors are limited to freewheels up to 7 speeds, and there aren't any that accept cassettes.

You will also find that a "true" road bike isn't suitable for conversion, as the frames were designed to withstand 1 human's amount of power with little extra strength. with a small motor, you can easily quadruple the power through the frame, which can turn it into a pretzel.

You will likely need to start with a Mountain, a Hybrid, or a touring bike, with a stronger frame. you can build it up as a road bike, using light weight components and racing bars, sear, tires etc.

The most importing part when using a front motor will be the fork. a good strong fork will be needed if you chose a front motor. CF won't work, and aluminum is almost as bad. they aren't designed to take force in the direction a motor will apply it. Your best bet is a steel fork.

You will also need a larger tire. 25c just isn't going to be able to handle the torque of a motor, or have enough traction for adequate stopping with the extra weight. 37C is the smallest I've had any luck with, but you might get away with smaller if you have smooth dry roads. I have been able to break traction on the front wheel with a 350w motor and a 2.5" tire in some conditions, so its hard to get wide enough.

As for the motor, there is a long list of 350W motors that should suit up to 5% grades. if you have steeper hills, you'll need a 500w motor. Its hard to give a specific recommendation with out more information about your riding conditions.

 

[adrian_sm]

Small geared hub will be very solid solution for low power assist <500w. But if you are looking for ultimate light weight or a bit more performance that a small hub, then friction drives can offer that.

You can get an eBoost from this link. http://www.eboo.st/ They are designed to be easily installed and removed, and mounted on the seat post so will suit most road bikes.

My friction drive (see link in my signature below) on a road bike comes in at about 14kg, for a 1000w of assist, and about 40km range with a 370wh LiPo battery in a saddle bag.

- Adrian

 

[amigafan2003]

CF won't work,

Really?

I beg to differ, as would Cytronex.

 

[MadRhino]

If I would be looking for a 250 W, road style Ebike, I would not build it.
There are so many that are readily available, of various quality and price to suit this need.

For me, building my own Ebikes has to be in the purpose of having better power and handling than any commercially available Ebike.

 

[adrian_sm]

You will also find that a "true" road bike isn't suitable for conversion, as the frames were designed to withstand 1 human's amount of power with little extra strength. with a small motor, you can easily quadruple the power through the frame, which can turn it into a pretzel.

You will also need a larger tire. 25c just isn't going to be able to handle the torque of a motor,

I disagree. I have thousand of kms on a road bike ebike, with 23c tires. I find the narrow tires are fine. Sure they don't provide as smooth a ride on bumpy stuff now that you are going a bit faster, but I wouldn't rule them out.

But I do agree that you have to be careful depending on the extra weight, and torque loads you apply to the bike. I would never have built up my first bike with 48V10Ah LiFePo4 headway pack, and a x408 hub motor on a road bike. But if you are careful and choose lightweight, and lower power setup you could make it work on a road bike. Going for LiPo helps as they are very light for the capacity. And if you go for a hub motor, make sure the torque and thrust is adequately resolved. It would definitely not be fun to have a hub motor fall out of your forks at speed.


- Adrian

 

[Geebee]

I just remembered this, exactly to you spec. http://www.niubike.com.au/e-ventura-road.php

 

[hoo]

Thanks all for the input.

Is there a good place for discrete easily pedalled bike with assist?
This place may be more tuned for high powered ebikes, but at least people seem to know their stuff.

Although i prefer the fact that a rear wheel can be pretty much entirely stealth, it seems the front wheel may make a little more sense.. and esentially i could just replace the front wheel/ remove battery and it would be pretty much a regular bike.
So, it seems that you can use the existing rim and spokes and just swap the hub for the motor, right?
..and what do people think of switching out the front fork for a Cro-mo one, on an Al bike??

Yes, amigafan2003, that is similar to what i'm hoping for (link is useful, thanks); although i notice it's steel so i'm hoping to be a fair bit lighter than that (most bikes i've been looking at are 10-11kg stock). How much of that weight is the batteries?? / what was the original bike weight?
The only other slight issue is that i was hoping for some more hill climbing ability than that-- i don't encounter hills too often, they aren't huge, and i don't expect to go up them that fast (maybe 10mph with light pedaling?).. but it is one area i think i'd appreciate some electrical assistance with. Would this require much sacrifice (financial or otherwise) ??

Geebee, what batteries/motor are you using? +3kg all in sounds great. And that bike looks lovely at a glance, but how much is it?

As for buying one; i'm pretty sure, by starting with a used bike, i'm going to get much better value/quality for building it myself. Not to mention that being in the UK, anything i brought would be limited to 15mph and 200w. Whilst i won't be going far greater; i think i can get away with a little more than these limits. I think i'll quite enjoy it, too.

I will have to check out the friction drive systems a bit more.. but anyway, it seems that it is atleast possible to create a decent hybrid e/pedal bike without destroying the benefits of a decent lighter weight road bike.

 

[Geebee]

$2,795 au dollars
My recumbent trike has a Tongxin motor (no longer available) and 5ah 24v Lipo's from hobbyking.com , I will run 2 packs for long rides and probably one for shorter rides they weigh 770g each. I find my Watts per km to be between 3~5 (very hilly) and if I am on a less hilly area at least half that, I like pedalling
Motor wise I was looking at bmsbattery.com for current replacements they have several 1.9 kg motors and sell complete kits minus the battery and they sell them as well.
I haven't bought from them yet but several on ES seem to have had success with them.

 

[Sunder]

Gee, I really hope this is not a bad place for people seeking advice on part pedalled, low powered bikes... That's my next build (Though I keep talking myself into delaying it and recouping more of the initial out lay for bike 1) and I've seen a lot of people ask about mini motors and extreme efficiency bikes, and get good answers...

From what I've seen so far, I'll be getting a flat bar road bike or hybrid around 12kg. The Trek 7 series look good. My wife has one and she loves it. I will then probably lace in a MXUS geared motor into the rear with a 7 speed freewheel. I will probably stick with stock tyre width, but I am tempted to get some light, aero dynamic rims and go full road tyres as I've modified my route to mainly avoid rougher roads now. On my commute, I'll probably carry a 14s1p battery, with the option to harness in a second or third battery to extend range.

I expect final weight to be around 18-19kg, which is lighter than my mountain bike BEFORE I made it electric...

 

[Geebee]

Sorry about the crack about the wrong place for low powered bikes, it's just that the majority here seem more interested in high powered bikes.

Try and keep weight down as much as possible, I just swapped my motor to my lighter trike (6kg lighter) and it made a significant difference in power usage, I will drop almost another 4kg when the new batteries show up.
Also if you are serious about pedal assist keep as many gears as you can.

 

[Sunder]

That's cool. I thought it was just a quip. Must be a bit like going on a modified car forum and asking about improving ride quality, fuel efficiency and dampening sound - they're considerations to most, and many know about it, but far more people just want to go FASTER!

 

[amigafan2003]

Yes, amigafan2003, that is similar to what i'm hoping for (link is useful, thanks); although i notice it's steel

It's alluminium and carbon fibre :wink: Stock weight is 11.5kg.

The only other slight issue is that i was hoping for some more hill climbing ability than that-- i don't encounter hills too often, they aren't huge, and i don't expect to go up them that fast (maybe 10mph with light pedaling?).. but it is one area i think i'd appreciate some electrical assistance with. Would this require much sacrifice (financial or otherwise) ??

Hills = heat. Heat requires a bigger motor to get rid of it. Hill climbing requires more wattage which also means bigger batteries (unless lipo'ing it).

 

[amigafan2003]

double post

 

[dogman dan]

The more I read of what you want, the more I get the feeling you would like a very small and light friction drive.

When I was saying just get a steel bike, I had this idea you wanted a street/trail bike. As I understand cyclocross, they pretty much carry the bike through the tough stuff.

I've seen a few dedicated pedalers go though the progression now. First bike is very light, perhaps a 300w rear hub with planetary gears. Light and very short range battery.

A year later, on thier 3-4 ebike they are building what many of us prefer and start with. Steel frame MTB, 500-1000w motor, 20-30 miles of range. Motor and battery weigh 20-30 pounds combined. The rider quickly has come to greatly prefer pedaling with a motor, than pushing a bike with the motor off. Not given up pedaling, just pedaling with power all the time now. Lighter weight stops mattering so much with a motor to help, so a 60-70 pound ebike is fine. Just carry lots of battery and never run out.

That's why I was saying basicly, get a bike that handles a motor well, and screw what it weighs. A small rear gearmotor and 15 pounds of lifepo4 makes a killer bike for riding long distances at 15-20 mph. Select a speed, then pedal up 2 mph more and your range extends quite a bit. You still get to pedal plenty, but you give up pedaling till you want to puke to get up hills.

Once you have 300-500w of assist, a 70 pound steel bike will feel a lot like you are pedaling a light bike. It won't have the lively feel, but the total effort to get there will be whatever you want at the moment. 0 effort or a good workout, your choice.

 

[Geebee]

There are some benefits to staying light, if I have an electrics failure my trike pedals just like a non assisted one, because you are still providing a lot of the power the fitness benefits are greater, if you need to carry the bike trike it is easy, cost of batteries, motor, etc are lower.
Range wise I expect to get down to 2w per km when the trike is finished which means a 24v 10 amp pack suggests a range of 100 km.

I have had the higher powered heavier bike, I sold it. Not fun to pedal, to heavy to do anything with (even with LiFe batteries) and knowing that if I was in an accident I would be looking at some massive fines.

Not everyone wants the same from an ebike.

 

[Sunder]

I've seen a few dedicated pedalers go though the progression now. First bike is very light, perhaps a 300w rear hub with planetary gears. Light and very short range battery.

A year later, on thier 3-4 ebike they are building what many of us prefer and start with. Steel frame MTB, 500-1000w motor, 20-30 miles of range. Motor and battery weigh 20-30 pounds combined. The rider quickly has come to greatly prefer pedaling with a motor, than pushing a bike with the motor off. Not given up pedaling, just pedaling with power all the time now. Lighter weight stops mattering so much with a motor to help, so a 60-70 pound ebike is fine. Just carry lots of battery and never run out.

Some of us are going the other way though. I started with the 18kg steel framed Mountain bike, added a 9kg 1000W Direct Drive motor to the front, a big heavy battery to the back, and the first few rides, I went all power, no pedal. First ride took about 80% power out of the battery, and as I got more confident with speed I've hit the LVC .

Then as I started pedalling more, I've found I've enjoyed some light exercise in the morning, to get there still pretty cool and relaxed, followed by a heavy exercise session in the return trip home. My best day has been 1.7AH out of a 10AH pack, what's that using only 17% of available power? I rarely go past 30% throttle these days, even on the steepest hills. Maybe if there was a car behind me, I do, but that's like 10-15 seconds out of a 45 minute commute.

The problem I have now is that:

1: The bike is too heavy. A full steel framed bike was heavy before I added 15kg of weight onto it. I don't lift it much, so that doesn't matter, but in terms of cornering, braking, general agility, it doesn't *feel* like a push bike. To say it feels like motorbike would be an extreme exaggeration, but if there was a scale between my carbon fibre roadbike and my old Honda CBR250RR, It's more like 30% like the later than 10% (Figures, I guess. The bike weighs low 30s, and the motorcycle weighed 150ish, I guess?

2: Pedalling with a large DD motor on front, does create a slightly strange momentum that's subtle and takes getting used to, especially at higher speeds. I don't know if that's because the rotating mass tries to keep you upright a tiny bit more than you'd expect or something. It's not huge, it's not something that you would immediately say "What's wrong with this bike"... But it just doesn't feel natural.

3: The DD motor does increase resistance when you're all pedal. Again, nothing huge. "Pedalling through sand" is a bit of an exaggeration as I've heard other people say it. But it is like getting on one of those old exercise bikes with resistance bands and clicking it just once. It doesn't really slow you down, but you do notice it.

4: It just looks like an electric bike. Only had 2 people give negative comments, and one person give a positive comment so far. But I'd like nobody to notice I had an electric bike.

This is why I:

A: Want to go Alloy, even Carbon\Alloy\Steel if I could.

B: Want to move the motor to the back, so it's less likely to affect steering. Also a smaller diameter, lower mass geared motor is less likely to have centrifigual forces acting on the bike

C: I want to move to a geared motor

D: I want to get the smallest, lightest ~300W hub I can, hide it behind gears and subtly wire the controller and battery to it.

I agree that I'm going against the grain here - almost everyone wants to go faster, and your points are totally valid. Add a hundred watts, and another 10kg makes little difference to the speed. But I think it does make a difference to handling, braking, the unpowered experience and stealth. I think if the OP has heard both sides of the argument, and still wants to go his original path, people shouldn't suggest that a year after he built his bike, he'd be going the other way... Because some of us do start off where you guys are - and want to move to a lighter, slower bike.

 

[d8veh]

If you live in the UK, you should check out the Pedelecs forum, where loads of people have done exactly what you want.
http://www.pedelecs.co.uk/forum/electric-bicycles/
If you want good hill climbing, you should get the Ezee kit. High quality, good support. Big discount if you buy this month:
http://www.ezeebike.com/Kit_product.htm
If you want style and stealth, look at the Oxygen kit:
http://www.oxygenbicycles.com/electric-bike-kit/index.html
If you're on a tight budget, the 8Fun kit, It also comes with bottle-type battery like the Oxydrive if you ask:
http://www.8funbike.com/detail.asp/sku=EK20F36R
If you're on a very tight budget and are good at DIY, get the BMSbattery kit:
http://www.bmsbattery.com/ebike-kits/423-bafang-250watts-front-driving-qswxk-motor-e-bike-kit.html
For a 250w motor, you can use aluminium or magnesium forks without a torque arm as long as the forks are not very light weight, and you must use the anti-rotation washers that come with the kit and do up the nuts tight. Nearly all the ready-made 250w bikes with front hub-motors have aluminium forks with no torque arms.

 

[Geebee]

Stealth wise,I had my trike in at work a couple of days ago and was chatting with one of the techs and said I had fitted the electric assist to my trike , after 5 minutes he says where is the motor, I said in the back wheel, 2 minutes later he replies there is no motor in the back wheel. I had to turn it around and show him the wire going into the hub to get him to believe me.
Now by the time the battery is in the water bottle no one will ever know its electric assisted as the motor is silent when running.

 

[999zip999]

Go with the keepler drive and a small battery. I wish I could say that bottle is large enough, so find someone how is using that setup.

 

[Sunder]

Stealth wise,I had my trike in at work a couple of days ago and was chatting with one of the techs and said I had fitted the electric assist to my trike , after 5 minutes he says where is the motor, I said in the back wheel, 2 minutes later he replies there is no motor in the back wheel. I had to turn it around and show him the wire going into the hub to get him to believe me.
Now by the time the battery is in the water bottle no one will ever know its electric assisted as the motor is silent when running.

That's what I want!