77dan77

Hi guys and girls

I am lookin' to build a bike trailer to take my dog to the park! But I also want to ride the bike to work during the week (with no trailer). Both destinations are 6km (3.7 miles) from my house in opposite directions.



I have the trailer worked out, done some research and development on the idea so hopefully I am within shooting distancing? I really like the 408 Crystalyte (rear wheel) for a number of reasons which most people already know, but am not sure it is suited for the dog haul once a week?

Bike purpose:
1) Get to work on a busy road using my learsport (5 days a week) with an electric motor (doing about 35km/hr, medium pedaling)
Bike=19kg (42lbs) Learsport BW3000 (with upgraded front suspension)
Me weigh=75kg (165lbs)
Total weight=94kg (207 lbs) [haven't include motor/batteries yet]

2) Take a smelly doberman to my local park once a week which has a mostly flat bus lane 90% of the way (doing about 20km/hr (12.4miles/hr) medium pedaling). I rarely see a bus on the weekends using the bus lane.
dog=35kg (77lbs)
trailer=21 kg (46lbs)
total haul weight=56kg (123lbs)

So the max total weight would be [94kg (bike and me)] + [56kg (dog and trailer)] + [20kg (408 motor,stuff and battery's and electronics??] = about 170kg (375 lbs)

I figure I am going to have to run it at least 48 volts (based on above details) and not sure what batteries to use. I would like to use 2*Dewalt batteries but they only come in 36 volt making it 72volts. Something like this maybe. I don't know much about batteries. I can wire up a your standard household surround sound stereo, car stereo etc. however diodes and fuses just confuse me.

Maybe a Crystalyte 408-4011 Dual Speed Hub Motor would be better than a 408? Does a dual speed last as long?

When I go to the park I might want to stay for an 1 hour, then ride home. I can't plug in anywhere.
At work I can recharge.

Am I heading in the right direction, what do you guys think? My problem seems to be that I want to be lite and travel 35km/hr to work and also haul and travel 20km/hr on the weekend, am I dreaming?

thanks in advanced

Abneycat

Your expected numbers aren't at all unreasonable, a lot of setups will get you what you're looking for. The one worry I have is the high amount of weight you're handling, how hard it would be to stay in control of the bike at higher speeds carrying a heavy trailer, your batteries, and anything else you were toting around. It shouldn't be too much of an issue for the bike since the Crystalyte motor is its own weight and not weighing down the bike, its the other way around. The trailer is also not resting entirely on the bike.

I would try to do some weight distribution tricks here. With the amount of weight on your real axle, putting weight towards the front of the bike could be good. Consider a suspension mount pannier rack, or try seeing if you can get a battery pack to fit in your frame.

The bike has its own weight limit not counting itself, do you know what that might be?

What are the steepest grades you're going to be facing? Whats your budget? On that bike, you'd have a hard time fitting anything other than a hub motor, so i'd say you're on track. bottom bracket/frame motors are meant to go on a traditional diamond frame, they've been mounted on full-suspension bikes before, but not with the little amount of clearance you have.

Crystalyte motors are good for their price range. They're reliable, and the one i've got came mounted on alex DM18 rims, which I presume they are in general. The DM18s will be tougher than whats on your bike now, and much more likely to withstand a heavier load. In general, these are plain, no frills motors.

You can get lighter/faster/stronger, but not if you're wanting to keep your budget under 4 digits.

Since it sounds like you don't have too many hills in your way, the 4011 would be too much torque output for your needs, particularily at that voltage. Some users have done the Dewalt thing successfully, but you'd need more than 2 of them to get any decent range, they've only got something like 2.4aH in them. Thats a common thing at visforvoltage.org, check there if you're interested in the Dewalt use.

If you're using your bike day in-day out, lithium and NiMH are great. SLA would probably push your weight budget too far, and with constant everyday use, your service life on them would be short. NiMH has an excellent service life, these batteries last. Lithiums are light and deliver constant power, excellent energy density.

48 volts sounds good to me. At 36 volts, it'll fall just short of your speed requirement of 35kph. Tops out at about 31-32 at that voltage. You'd also have less torque to play with if you needed it. The 408 is a fairly good torque output motor however.

The 408@48 will provide a speed of roughly 40-41kph with balloon/hardpack/street tires on your bike. Since high speeds with a trailer are dangerous, I wouldn't go with anything more than 48v, and if it was me, I wouldn't ride with the throttle flat out. 48v on the 408 will carry you up a great deal of slopes even with a heavier payload.

On the subject of tires, if you're still using your original knobbies, spring for something like a Schwalbe big apple or another type of city oriented MTB tire, your range will skyrocket.

JeanCoutu

Try getting road slicks & replace the rear shock with a pipe, stiffen up the front.
Fit your bike, if that's not done: https://www.coloradocyclist.com/BikeFit/index.cfm

Should be able to do the distance/speeds you're aiming for without a motor given a bit of practise.

Otherwise, in the parts of the world with the most generous max speed for electric bikes, 32kmh is it. More then that and you're talking about a moped or something, which is fine too but an ebike it ain't. A motor that cuts at 32kph will boost your speed up a lot cause you hardly have to put much energy at all to go 0-30, so you have it left to hold rather higher speeds then you normally could between stops and lights and such. In other words, the 36v 408 with moderate pedalling is likely to do the trick quite nicely.


Edit: this comes to mind:

Abneycat

I agree with what JeanCoutu says here as well, fit is very important.

If your rear shock has a rebound, you can slow the return. This will make rocky/gravelly surfaces no more comfortable than they'd be on a hardtail, but it'll work better in tandem with your movements, which gives you *much* more power and allows you to sprint/climb without pogoing nearly as much. The shock will still soften the blows if you like to do urban maneuvers like curb hopping, or if you find a pothole.

I didn't realize your range was 6 miles. Thats a pretty short run with or without electric. Jean might be right, if your dog isn't going to need a lot of dragging up hills you could probably do without it altogether. Then again, once you get it, you might find that its practical for many things. Mine replaced my desire for a car almost altogether.

77dan77

ok, I am going to get the 408.

I didn't think of that, I might go for 2*12V batteries on a front pannier and 2*12V battery on my existing rear pannier to make 48 volts. Or maybe I should put 2*24V batteries on the front? Like you guys said SLA batteries are kind of ruled out because of weight, so I am left with NiMH or lithium.

I can get a LiFePO4 24V 18ah for about $550. I want 2, so it will be $1100 aud ($1005 usd), 12.4kg (27.3lbs)

Or maybe 1 lithium battery up front?? making it cheaper

I can get a LiFePO4 48V 18ah for about $900 aud ($822 usd) ...8.8kg (19.4lbs)

I haven't shopped around yet, so still have to compare prices and NiMH option (hoping they are at least 30% cheaper?, so might take that option...) Also not sure what ah means so am guessing the higher the better, the 408 kit I am looking at comes with a 20Amp PWM controller.

I have done a fair amount of scary downhill mountain biking, sometimes carrying a load on the back pannier so I am not too worried about rideabilty at this stage due to my experience, I am fairly comfortable with potholes and gutters but of course not with my dog in a trailer, I will be taking it easy and doing some test runs. I'm not sure how much the bike weight limit is.

Re: hill slope... If we use the scale for the average 30yr old male on a SAD diet (citizen not bike-rider); say 0/10 is flat, 2/10 slight work, 5/10 is your average hill with loss of breath and a noticable amount of work, 7/10 steep hill with lots of energy, 10/10 the average person couldn't ride it and would have to get off there bike to walk.

There is one big hill rated 8/10, but it is only 100m long (317 feet), so I am excluding it from discussion and if I can't make it up with my trailer and dog, I can let the 35kg fart bag walk it! hehe

The other 2 hills are rated 5/10 and are 350m (0.22 miles) long. I could probably climb this hill (with a dog+trailer) in a low gear without electrics but I don't want to wear myself out before I get to the park.

Thanks for the photo JeanCoutu, and both of you for your tips. My list of things to do got shorter...

Abneycat

Dan, 18ah of lithium is a *lot*. Probably a lot more than you need. Lithium packs provide a more constant power output than the other chemistries, and allow for a greater depth of discharge than SLA. Lithium is deceptive in this regard, because you actually end up with about 30% more range on a "same spec" lithium than you do SLA.

An 18ah pack rated to 48v would give you a rough range of about 118kms@32kph, if you built for efficiency. My 10ah pack will go about 66kms. 48v/18aH is a seriously large battery, you'd not be using it to its fullest unless you went long distance touring

LiFePO4 is a great battery chemistry. Not as light as Li-ion, but safer. LiMn is a good choice too.

I would suggest looking for something smaller for everyday use, but not too small. I'm pretty content with the 48/10. For a 6 mile trip you could get away with a lot less, but you wouldn't want to limit yourself to just the 6 mile run: if you're anything like most people who try these things out, you'll be addicted fast!

As for 36/48, which voltage to choose? Well, are you in Australia? I'm just guessing from the values in aud. The 408 is already out of the watt limit, but you can still obey the speed limit and no one has to know about the specs on your motor. A 48v battery will carry more energy per ah, and weigh more proportionately. The efficiency and range on the battery is the same *at the same speed*, if you start speeding past what the 36v system can do, you'll lose range due to wind resistance. But you don't have to speed, and having the extra current to help you on the hills is good.

2manybikes

I did run that with an old zap motor and two car batteries when I broke my toe. It would go 16 mph for 12 miles on a pretty flat surface. It would go a lot farther at 10 mph, but I can pedal that fast with a broken toe. It's not worth having a motor for that speed.

Currently dog and trike with water and tools etc. are a little over 100 lbs. A typical ride for us is 25-30 miles. Two or three times a week during the nice weather. A motor and battery would ruin the traveling distance and the exercise (fun) for me.

I could ride this thing 100 miles, but it's very slow, Bailey would not like it, and I would have to travel 7 mph average. It would take around 14 hours of pedaling and a least an hour of rest stops, probably closer to two. All you need if something is heavy is low gearing. All you lose is speed. For a 3.7 mile ride it doesn't matter how you power it or how fast you go. You could walk the dog that far.

You can buy a kiddie trailer on Ebay for what it would cost to build one if you need to buy bike wheels at retail. Lots of big dog owners do this.

However, it is a lot of fun to build a trailer and an electric bike. And nice to ride something you built.

Edit: Don't ride fast near traffic with a big dog in a trailer, handling and stopping is very, very, poor. 10 12 mph is safer.

chicbicyclist

I just used a simple children's trailer(Burly is my first choice) that can carry 100 lbs. I carry my pitbull(55 lbs) and my chihuhua/jack russel(30 lbs) mix around Ocean Beach, San Diego(if you live in the area, you've probably seen me!) using a Wilderness energy kit, stock, 36 V Brushless. I even go up hills in Point Loma since I live right in front of the Nazarene University. I use slick tires on my bike and stock wheels on the trailer.

I travel about 10 miles round trip, 2-3 times a week to the beach(Dog Beach) but I've gone on longer miles when I used to live in Hillcrest. Both instances involved quite a bit of hill climbing, especially in my current location.

Your area sounds really flat, you should be fine if you're gonna settle with 36v minimum, and I don't really advise going over 15mph(25km/h) when you're toting around your puppy. The 48 volt is nice for the added torque, but not for the speed, imo. Everything would be flying all over the place, it's not too comfortable for the dog and you'll have issues with stopping, even with a well made and sturdy trailer at 20mph(35km/h)

A few tips though if you're gonna go with the child's trailer route:

1) Go buy a 20-30ft rock climbing rope, 1/2 inch up to an inch. Use that to weave a support structure under the trailers using the metal frame of the trailer itself. A stock child's trailer has flimsy floor support. Buy the rock climbing rope from a sporting good store like Sports Authority or some other place. Try to make a web of support using knots every time and make sure they're tight.

2) use the rope that plastic fasteners with the snaps to secure your dog using a body lcollar(for dogs, buy this at the pet shop). These usually come with the trailer and they are used to secure the child. Take them from the fabric part of the harness and tie it to the metal frame using a secure knot and snap your dog in place. I usually have at least two on each dog just in case the first one fails, one of the body collar and one on his neck collar.

3) remove the top casing of the trailer. You won't need it.

4) do not go more than 15mph(25 kmh) just to be safe for both you and your puppies!

5) don't buy the cheapo trailers, they're not worth it.


I'll try to have pictures up of my set up tomorrow

Endless_BiGH

77dan - i'm also in Aus (vic 2 be exact), running two 36v 12ah batteries as 72v 12ah. this is enough to get me 30k through some very hilly areas at high (39-40kph average) speed. you are getting WAAAY too mcuh batteries. using the batteries individually meant i could get 70k+ in total at full throttle.

you'd probably also be better getting a single 48v battery pack. designed for 48v. it also keeps the weight down.

Don't even consider lead - its junk,and 36v on a 408 will bog down on hills with enough weight - you HAVE to keep peddling no matter what. i'd probably suggest a 408 motor, 35a controller (get one of the new ones - they have really good bits inside) and a 48v lithium pack. On a 36v lead setup, i had issues with hills, in that i'd slow right down to about 20kph going up them, and i'd ride around with the throttle jammed on full. at 48v it was a bit better, since 48v provided enough speed that i'd modulate the throttle a little - back off on the flat, but full throttle up hills.

72v is another story all together. the power it can put down is crazy, i've flown up some very steep hills at 45kph without an issue.

However since you're looking to carry a trailer / dog i'd highly reccomend either keeping the voltage to 48v max, possibly getting a 409 motor or 410 to provide more torque to pull the trailer but lower top speed, or getting something like a cycle anaylist to artifically limit ur max speed - so if u are pulling doggy, then you don't have to worry about going to fast.

Also i echo what everyone here has said about slicks. invest in some good ones that have puncture protection (i use specalized armadilo nimbus EX tyres) - never had a puncture flat with one. (the rim did tear into one tube due to ill fitted rim tape - but thats not the fault of the tyre).

good slicks will go you about $40-50 AUD a tyre.

2manybikes

Good points, very important.

I just want to reinforce the idea about using a harness to keep the dog in. It's very important. Bailey can not possibly get out of his basket. It may look like he can. But he is wearing a car seatbelt harness and shackled into a swivel at the bottom of his chest. He can sit, almost stand and turn around. But not get out. One running squirrel nearby and most dogs would be jumping out.


I am repeating myself........Don't go fast with a dog in a trailer. A panic stop could jacknife your rig. No brakes on the trailer!! The bike will corner fine as you corner too fast and the trailer tips over.

chicbicyclist

I use 36 v on a tough hill, muahahahaha. Though I can only climb it one time on my lowest gears because I won't have enough power to get back home.