So I have had this extra woman's Giant LaFree that I have been looking at turning into to something useful. I though about a trike, do not like the idea of three wheels, slow, difficult turning and too bulky. A recumbent was out, do not like the idea of not sitting up high, you lose the visibility advantage. So I thought why not a fast fully suspended street bike. The streets in San Diego are poor to begin with and I always find myself watching the condition of the road more then I should. A good front shock with a couple of inches of travel would be nice, the LaFree has one, but it does not seem all that great. Rear suspension would be a fairly big modification. I think I can get away with grafting a mountain bike on to the back half of the my bike. The pivot point seems to be key, there looks like there is a natural one on my bike.
Here is what I'm shooting for.
1) The bike does 22 MPH with pedal assist in stock form, would like to up that to like 30 to 35 with pedal assist.
2) Full suspension.
3) Good front shocks.
Some questions.
1) The bike has a 24V 400W 1,000W peak motor, can I get 30 to 35 MPH with pedal assist out of that motor? What voltage would I need to run?
2) If I make frame modifications can I weld to them, are they heat treated?
3) Whats a good brand of front fork that with a couple of inches of travel?
4) What about brakes, the brakes that are on it now seem pretty dam good, I can slow down coming down a hill at over 35 MPH feeling like I'm in real good control.
Deron.
So I picked up a cheap aluminum mountain bike for the frame and the pivot point. The pivot point is critical, needed it in the right spot to be able to attach it to the LaFree frame.
I took my sawsall to the LaFree, no turning back. I'm in the process of making a custom bracket for connecting the bikes together.
Looking for a source for some good forks, anyone know any?
Deron.
Today I made the pivot point bracket and attached the bikes together. I mounted the shock, but do not like the steering and seat post angles, so I'm going to move the shock mount rearward. Rode the bike, it's has the forward leaning feel of a mountain bike, going to try to make more of upright sitting position. My fear that the bike would not feel solid is not a problem. The extra suspension makes for a cushy ride, might be too soft, it's adjustable though.
Still looking for some really good front forks.
Been trying to find out what will happen with running more voltage. The bike will go faster, but will the motor draw more current or less current. Need to size the controller, I guessing at 36V at 1,000W.
Deron.
I improved upon the rear shock mounting location. Replaced the stock fork with a better one and better handlebars. The bike rides much better now, the full suspension smooths out the road bumps pretty good.
I tried some SLA batteries today, first I put 24 volts of power to it, then I went up to 36 volts. The extra 12 volts made a big differance, going to have to add a bike speedo to see what is happening. I just used a heavy duty push button switch, that seemed to work pretty good, has me wondering if I even need a controller.
Going to fully charge my SLA batteries and get a speedo and do some more testing. I have enough batteries so I can test it at 48 volts, that should be fun.
Deron.
I improved upon the rear shock mounting location. Replaced the stock fork with a better one and better handlebars. The bike rides much better now, the full suspension smooths out the road bumps pretty good.
I tried some SLA batteries today, first I put 24 volts of power to it, then I went up to 36 volts. The extra 12 volts made a big differance, going to have to add a bike speedo to see what is happening. I just used a heavy duty push button switch, that seemed to work pretty good, has me wondering if I even need a controller.
Going to fully charge my SLA batteries and get a speedo and do some more testing. I have enough batteries so I can test it at 48 volts, that should be fun.
Deron.
I put a speedo on the bike and retested it at 36 and then at 48 volts. At 36 volts I was able to go just over 25 MPH, upping it to 48 volts allowed me to hit just over 30 MPH. These were assisted speeds with me pedaling at a pretty good pace.
At 36 volts the motor did not heat up much, at 48 volts the motor started to get warm. I was thinking 36 volts would be safe and 48 volts would require me to add some cooling if I wanted a reliable set up.
Going faster, the cost starts to climb pretty quickly. I would need a substantial battery pack if I wanted to go 30+ MPH and have decent range. Lead on a bicycle starts to get too heavy. At a minimum you would need 40 Lbs of lead, but at the faster speeds you would not have much range. And you really do not want to be carrying all that weight around at those speeds on a bicycle. LiFe would do the trick, but you are looking at $$$$$.
I'm thinking I would go with the lower 36 volt LiFe pack to keep the cost and weight down. At the lower voltage I would go a little slower, but I would have more range. And at 25+ MPH that should put me at a speed that will keep most people from wanting to run me over to get around me.
Deron.
I just bought a La Free, so I'm very interested in your project and the results of your experimentations! Could you post some pictures or send them to me privately?
I'm not interested in chopping my bike up at this point. I'm just interested in getting the most out of the drive system. Did you do any changing of the gearing? I haven't counted the teeth on the chainring yet, but it's obvious that it is way too small for the kind of input I would want to put into the system physically. I want to go kind of in the opposite direction as you with a less upright, more aggresive riding position. I might ditch the front fork. Here in the high mountains of Colorado such a fork is laughable. Useless and heavy. What fork did you end up with? For now I think I'll go with lighter wheels and narrower tires. And seeing if I can get a regular bike crank far enough to the inside as to not overly stress the chain.
How did you over-ride the speed sensor on the rear wheel, or did you? It seems like you must have in order to reach those speeds.
OK
Here are some images of what I did to the woman's Giant LaFree. I took a look at getting some really good forks, but they wanted big bucks for them, so I just put some slightly better ones on that I stole off of one of my other bikes.
Right now I'm thinking I will get a custom 36V 20Ah Ping pack built to fit in the stock battery box. I have not done much to the bike lately, the cost of the battery has me waiting and thinking about different options.
As for bypassing stuff, I just tore all the electronics out of it, they will make good spares for my unmodified bike. I'm just going to go with a heavy duty push button switch to start with. I will see how this works before deciding if I want to invest in a controller...
I'm pretty happy with the results so far, the bike was just sitting collecting dust, so it's turning out that I may get a lot of use out of the bike.
Deron.
I would not change the gearing yet if I were you, I was able to hit 32 MPH with pedaling and motor assist. I would wait till you have done some testing. See if you can scrounge up some batteries, bypass the electronics by just hooking straight to the motor with a switch in the line.
From what I have found, 24V LiFe will work with all the stock electronics in place. I did not try 36V on the electronics as I'm pretty sure nothing would work and it could very well fry some things. 48 volts seems like it would overheat the motor in short order, these things are sealed and have no real good way of getting rid of heat. Even if I get a 36V setup I'm going to have to keep a eye on the motor to see how much heat it builds going up some of the hills in my area.
I also though about changing out the tires and wheels, but they are really well suited for a heavy bike. I just make sure I keep them inflated to 75 PSI. I have also taken the bike off road a few times and the tires work good there.
Deron.
Thanks a lot! That is really cool!! I think I will wait on the gear changes.
So what you're doing with the 36v is just running the battery straight through the switch to the motor? The weather is cooler here close to Vail Colorado, but I would tend to think that the hills are steeper and longer than in San Diego. Around here a finned heat sink like I see on some motorcycle oil filter casings might go a long way toward keeping the motor cool while over-amping it, don't you think?
Terry
Nice progress...few things...DEFINITELY go with the Lifep04 pack (ping pack...there are now other sellers making 'fake' ping packs' they dont all use the same cells some do and they are cheapoer than ping) you wont regret it and for a speed controller check TNC Scooters...they are the cheapest suppliers on the net you will pick up a controller for under 100 bucks suitable for your needs... Sent off a pm that also will asssit...
Kim
Did you get 32 mph with the stock bike or with the mod bike? Was that with 24v or 36v?
Thanks, Terry
Terry
Yeah, real simple, positive goes batteries-switch-motor, negative goes batteries-motor. The reason I'm going to try the set up without a controller is, on my unmodified Giant LaFree I use full throttle all the time. Losing the controller saves money, weight, precious battery power and is simpler.
I though of the same thing, a heat sink for the motor. I'm going to have a look at those motorcycle oil filter heat sinks. The other thing that can be done is to put a temperature switch in the motor and either have a warning buzzer, light or a disconnect.
I tried out 36V and 48V on the bike you see in the pictures. At 36V and pedaling I was doing a little over 25 MPH, at 48V and pedaling I hit 32 MPH. Now for the testing I used some old SLA batteries I had laying around and wire that was too small and too long. If I had used LiFe batteries and proper wiring you could probably add a couple of MPH's to those figures.
The stock bike I have has 24V 20Ah Ping LiFe batteries and will do 18 MPH with no pedaling and 22 MPH with some pedaling.
Kim
Yeah Ping is the man, looked around again to see if there is a better deal and can not find one. I checked into the real good cells from BMI, but it was $970.00 for a 36V 10Ah pack. I think I can get a custom made 36V 20Ah pack from ping for around $550.00.
I will check out those controllers you mentioned as I may go that route.
Deron.
This is kind of what I'm thinking about to keep the motor cool.
http://cgi.ebay.com/ebaymotors/Toyota-Oil-Filter-Cooler-Heat-Sink-Fits-1968-to-1984_W0QQitemZ230234031011QQcmdZViewItem
If you could find the right size it would be perfect for the bottom bracket mounted motor on the LaFree.
Terry
Hello, i know it's a long time ago that you posted this but i really want to ask something,
it might sound stupid if i ask this but what do i have to do if i want to go faster, do i have to buy a new motor or can i tune the motor or something?
Deron,
I know this blog is sooo old, but here goes a try...
Your Lafree drive setup is different that the one I have. In all of my research, I have never seen the one you have with the motor sticking out front. Mine is the one with the motor bolted to the left side of the drive case (Panasonic). It is 24V and has the 6.5AH NiMH batteries. I do believe I am going with a Ping LifePO4 36V 30AH.
My drive has all the torque sensor apparatus stuff. How did you wire this to bypass the torque sensor and onboard computer? Any pics available of your wiring?
Thanks,
Steve
Center drive bikes are my thing.