will this bike make a decent conversion?

[transposon]

I am a ebike noob. I have a schwinn prelude 700c road bike. It has an aluminum frame with steel forks. I was thinking of a front dd hub motor for simplicity.

here is a link for reference.

http://www.amazon.com/gp/aw/d/B004QM22HC/ref=redir_mdp_mobile

 

[neptronix]

Front low powered geared hub, OK. Anything beyond that, go rear motor.
Bikes like that don't often have good rear dropouts. Looking at that one i see crappy rear dropouts..

How fast do you want to go? for regular pedal bike speeds ( 20mph or under ), this will work.. anything above that, you'll want to reconsider.

 

[transposon]

I was thinking of a top speed of about 25mph. What if I were to reinforce the front fork?

I also have a steel mtb that has non-steel fork crowns. would that work better?

 

[john7700]

Steel Mt. bike, rear wheel drive. Be Happy

 

[Russell]

I am a ebike noob. I have a schwinn prelude 700c road bike. It has an aluminum frame with steel forks. I was thinking of a front dd hub motor for simplicity.

here is a link for reference.

http://www.amazon.com/gp/aw/d/B004QM22HC/ref=redir_mdp_mobile

You need to check the dimensions of your front forks to see if they'll clear a motor. The forks need to run parallel or at least not have too much of an inward slope to them.

My first e-bike was a drop bar touring bike I converted to flat bars (makes mounting a throttle easier too). It had slender chromoly steel forks and for a brief time I ran a big 9C motor on that bike;



Most of the time however I used a Bafang. On the bike shown above I employed shorty torque arms bolted to the rack eyelets like so;



Your forks have fender eyelets so you could use this torque arm from ebikes.ca;

http://www.ebikes.ca/store/photos/TorqArmRev2.jpg

However the most important thing for a motor installation on any bike and especially with front forks is ensuring that the washers are flush and the nuts are properly torqued. On my first bike I filed off the "lawyer lips" but on the second and now the third I ground down the anti-spin washers to fit within the protrusions (http://endless-sphere.com/forums/viewtopic.php?f=2&t=10664#p163383). I rode the second bike thousands of miles without a torque arm of any kind. You can now buy 'C' washers to fill the space instead;

http://www.ebikes.ca/store/photos/SpaceCWasher.jpg

Also speed isn't what really stresses the dropouts, it's the high torque developed when first starting or climbing a hill. You can lessen the stress greatly by pedaling from a stop, up hills and by keeping power at a reasonable level.

-R

 

[dnmun]

this is such a great personal testimony from russel to those who are building up a bike for the first time. proof is in the mileage accumulated, and he did a great job with the torque plate and the discussion of how important it is to make sure the nut sets permanently when torqued down by removing the lawyer's lips or the C washer. it is so important to avoid a failure of a front hubmotor mounting at these speeds.

i also think the torque from the motor is what creates the stress fractures at the edge of the dropout corners. the aluminum forks just break off but the steel forks need to grow the crack and the torque loading one side of the dropout while under vibration is the stressor for that system of crack propagation.

the tighter the fit of the axle in the slot the less it can move so that also increases the reliability, and of course the key need of the torque plate is to hold the axle in place on the fork if the dropout were to ever fail. so the wheel doesn't get jerked out of the fork if the dropout fails.

i have also filed the inside corners of the dropout square and then fileing the back side of the axle so it will fit that rectangular side of the axle into a rectangular notch cut squarely with a file into the corners of the dropout. my theory is that this minimizes the torque loading by reducing the motion of the axle in the dropout, so over the life of the system the amount of stressing is reduced. so any crack is not propagated as rapidly.

i always liked your builds, very practical too.

 

[biohazardman]

Nothing wrong with aluminum frames for conversions unless you are building a race bike or something. I have an older Schwinn MTB with a rear DD GM 500W @ 48V with over 4K on it and a Giant Trance3 with a BMC V2 @ 66V with 5K both aluminum frames rear motors and neither has had any sign of dropout problems. Yes they both have torque arms. The Giant has it's share of trail miles and curb jumps as well. With the right axle washers and nuts that fit flat and are kept tight it's not likely you will have any problems. There are plenty of aluminum framed ebikes out there. If I were to build a front motor bike I would go for the steel though.

 

[kmxtornado]

Maybe someone can chime in on the differences of using a road bike. I don't know much about road bike e-bike conversions being that I'm sort of a newb myself having just finished my first one not too long ago. But I figure there's got to be a reason why most people out here are using mountain bikes and hybrids. Perhaps the frame is stronger? Wider tires is better? Not sure on the details, but I'm sure there's a reason why people shy away from road bikes. Maybe the experts can say a few words on this topic.

 

[neptronix]

4kW / 115ft-lbs to the rear of a hardtail aluminum bike. Takes it like a champ. Pick the right aluminum frame, make good torque plates and an alloy bike will take the abuse all day long.

Don't forget that DoctorBass runs aluminum bikes..

 

[Russell]

Maybe someone can chime in on the differences of using a road bike. I don't know much about road bike e-bike conversions being that I'm sort of a newb myself having just finished my first one not too long ago. But I figure there's got to be a reason why most people out here are using mountain bikes and hybrids. Perhaps the frame is stronger? Wider tires is better? Not sure on the details, but I'm sure there's a reason why people shy away from road bikes. Maybe the experts can say a few words on this topic.

Much of the reason is parts availability and compatibility but riding background has something to do with it too. Rear motors require at least a 135mm rear OLN (Over-Lock-Nut) spacing which mountain and most hybrids have while most road bikes are 130mm. Also throttles are made for 22.2mm handlebars (mtb) only. Furthermore 26" bikes are cheap, plentiful and universal so ebike kits are 26" first with 700C almost an afterthought. Road bikes are built to be lightweight often with carbon forks and simply not well suited for conversion. Also folks who ride Road bikes generally seem to have little interest in motorizing their bikes, and many of the “Roadies” think it’s somehow “cheating” to do so.

For me my first ebike was really an experiment to see if I'd like it or not so I chose a bike I had on hand which was best suited for a motor; an early '90's 700C touring bike converted to flat bars with roomy front steel forks. It also had inbetween rear spacing at 132.5mm that easily stretched to 135mm if I wanted to go with a rear motor. I've pretty much stuck with 700C because except for one commercial 26" ebike I bought and sold soon afterwards I've always ridden on big wheels.

-R

 

[dogman dan]

The first timer often expects the ebike experience to be just like the road bike experience, but better. I did.

In fact, it's quite a compromise to put a large heavy dd motor on a lightweight, skinny tire roadbike. Some would call it ruined by it.

It's just too much like a moped to put on a featherweight bike and have it ride like you are used to. But the much smaller, much lighter, less powerful gearmotor approach can make some good sense. With a super small battery, and used more as assist, you can go miles on little extra weight added.

For me though, give me some wider 26" tires, and a very stiff MTB frame for an Ebike. Because of my bad back, I really want full suspension if the ride will be longer than 5 miles too. In this case, the bike didn't pedal for shit on the street in the first place, so you never feel like it's ruined the ride of the bike. Carry a big enough battery, and you go miles and miles. You can still pedal all you want if you are a pedaler. Cruising nealy effortlessly at 25 mph for 20 miles or so with no worries about skinny tires and sharp rocks is wonderfull.

 

[transposon]

wow, thanks so much guys for the quick and thorough help.

I am also considering a mtb, it has steel forks except for the fork crown, it is metal but a magnet doesn't stick. would this pose a problem?

 

[dogman dan]

Some think so, I don't. I'm one of the few willing to run front hub on alloy fork dropouts. But I never recomend it for a first bike. I don't worry about the alloy crowns. If they were made to handle disk braking, they are strong enough. Alloy lowers and dropouts are a serious problem that requires a perfect installation of washers and torque arms, plus limiting wattage and regen.

Cheap suspension forks with steel lowers work fine with motors such as Ebikekit or 9 continent dd motors. Like Russels big motor in the pics above.

Front hub vs Rear hub is another unwinnable argument like Cut taxes or cut spending. No right answer for every need. RH is pretty much mandatory for highest power and for dirt riding up steep slippery hills. But I still love my front hubs for street riding at "normal" speeds and wattages. The front motor allows more weight to be carried in back with less effect on the bikes handling.

No such thing as a perfect solution. I have 5-6 totally different ebikes, all perfect for one thing or the other.

 

[transposon]

it looks like the front fork has some suspension built in. Would this make a rear hub motor preferable?

the bike is a gary fisher tarpon

 

[john7700]

You don't want to hassle with trying to put a hub on that cheap arse RST shock. Also, unless that is a real old frame that I haven't seen, the Tarpon was an aluminum frame model. You will need torque arms or plates. And please, clean that nasty old rusty thing.