Noobie alert and critique my system!

[White2505]

Hi all,
been fascinating reading the forum over the last few days picking up info.
I'm in the UK and looking to dip my toe into the EV water for the first time.

Ultimately I want a system that will let me tow a bike trailer to the beach (about 6 miles each way) with my kayak on it for a bit of surfing.
I want to sort the bike out first though with proof of concept, before I get ahead of myself and attach the trailer to it.

I have a nice new aluminium TT frame which I'm almost finished building into a flat bar cruiser with 3x7 on-road suitable gearing which will be the intended victim for this set-up.
This is what the frame looks like.

obviously this uses 700c roadbike wheels. Specs wise the overall weight of me and bike comes out at around 80kgs plus another 25kgs for the trailer.
I'm not looking to be a speed freak and I'm happy doing some of the work on the pedals. I figure torque is more use to my application than overall top speed.
If I can cruise around 15mph there and back with trailer I'll be a happy camper. It's not overly hilly just a couple around 10% at each end of the ride.
I intend to have a rear rack with some sort of lockable pannier to carry the battery/ies and controller nice and low down. Ideally I want the bike looking as regular bike like as possible rather than some kind of frankenbike.

kit wise I'm spec'ing the following as my starting point.

Rear hub motor around 250w
4qd porter controller, upto 36v and 30a continuous. (will do up to 46v and 40a peak)
thumb throttle
6 cell 5500mah Lipo battery pack with BMS connector (approx 22v)
BMS lipo charger and supply

I figure this will get me into the game but I think with this battery I'm short on the range.
If the concept works well I can buy another pack and presumably parallel it for an increase in range.

Have I overlooked anything critical?
I'm looking at a seven speed rear gear cassette, do the rear hub motor use standard shimano cassette's or do I need a specific cassette?

cheers
Andrew

 

[White2505]

Looks like they all use a screw on cassette which is readily available so that's another piece of the puzzle sorted. Just looking at a critique on my system.

 

[Ricky_nz]

The controller you have specified looks like its for brushed motors whereas most modern hub motors are brushless requiring a different controller.

 

[White2505]

Cheers Ricky,
yep, spot on, I'd overlooked that.
Time to start hunting down a suitable controller.

 

[neptronix]

Ah, wimpy frame meant for road biking. I wouldn't advise putting much more than 500w peaks to it. This is why we generally all use mountain bike frames.

 

[White2505]

Yep roadbike frame, not ideal but lets me dip my toe in the water without butchering one of my nice bikes
If I dig the whole EV thing then I've got plans afoot 8)

 

[neptronix]

Ah, but used mountain bikes can be had for nothing, especially if they have a trashed rear wheel.
You could sell off that frame ( or hang on to it ) for the price of say, a used trek/giant/whatever.
It would be a better chassis to start on.

If rolling resistance is something you're concerned about, there are plenty of great 26" tires out there in the 1.0"-1.5" range.
As you go faster, you will want fatter tires and better brakes. That's another reason why a MTB frame is a good starter.

Almost guaranteed you'll get hooked on electric power and want more. I did

 

[dogman dan]

Only additional problem I see is wanting to run about 1000w into a motor intended for 250w.

You need about 1000w though, to pull that trailer later, if not more. I suggest a larger motor, such as a Mac 10T or 8T. 10T might be best for towing, since it's slower. With a suitable matching controller of course. 20-30 amps.

Nothing seriously wrong with going with the 700c idea, uless you have an old steel mtb in the garage. You don't need particularly low rolling resistance or larger wheels for a bike with 1000w of power avaliable. You'll pedal along with it, but you won't be pedaling it that hard.

Battery, at least two of the 6 cell packs, series connected into 44v works good. If the battery weighs more than 8-10 pounds, carry it on the trailer, or in the front triangle of the bike. Just two packs is light enough to carry anywhere, but a 15 pounder will throw off the balance of the bike too much when added to a rear motors weight. For 12 miles, you'll need at least 10 ah of battery. Maybe more hauling the boat if it's windy.

 

[Drunkskunk]

Welcome to the forum. We don't suger coat things here, and you did ask for a Critique....

First problem: That frame is a Ribble-TT. roadbikes are generaly too light weight to make good Ebikes, but a TT, Time Trial bike is even worse. they are built for speed, with every ounce devoted to surviving 1 human power, Double it's power with a little 250 watt motor and you're headed for failure. (And that motor is too small for the job, but more on that in a minute). There is a good reason that frame has no rear rack eyelets, it wouldn't handle the weight or the stress of one. Cross that frame off your list. Bare minimum is a touring style bike. Better yet, a hybrid, and Best of all, a steel framed Mountina bike.

General best recomendation for a first Ebike is a Trek 800 series or something similar. They can be had dirt cheap used and will meet your needs.




Second problem: That motor. 250 watts is fine for a slow beach cruiser on flat ground, but not up a 10% grade, not pulling a trailer, and esspecialy not both. Depending on which brand 250 watt you picked, I'd expect the motor to have melted it's self to a puddle of nylon and pile burned windings within the first 2 rides, especialy if you tried to use it with a 36v 40A controller.

To pull a trailer loaded with a Kayak you need a minimum of a 500 watt motor. You mentioned a 10% grade like it wasn't much, though a real 10% grade hill blows car engines, and large trucks won't even attempt them unless its short and they get a running start. How sure are you that it's a 10% grade hill?

A motor like a MAC 10T or 12T may be what you need, unless that hill is long. And you're going to want 48 volts with that.




Third problem: The battery. I don't recomend Lipo to first time Ebikers for the same reason I don't recomend Nitro Methane to first time drivers. Its not safe. It can't be made safe. Its only safe to use if you're safe with it. It's labor intensive to be safe with it. Lipo Is the Pyromaniac of batteries, and there are well disiplined and responsable members here who did everything right with theeir lipo and still had a fire.
Lipo is what you use when performance matters, and you can accept the extra time and work it's going to take to make your bike slightly better than it would be if you used something like LiFePO4.

I highly recomend LiFePO4. Its much easier to live with.

 

[White2505]

thanks for the info. No offence taken.
Like tackling any new thing in life I don't know what it is I don't know yet and certainly don't expect to get it right first try!
I have a mountain bike but it's nice and gets thrown around in the mud and down tracks a lot. Not really looking to butcher it at this stage.
I live in a very hilly part of the UK and cycle quite a lot (about 3000 miles a year on average)
The hill out of the beach carpark is pretty damn step, certainly granny ring material although fairly short at about 75 metres long.
The other couple are significantly less gradient than this probably around 5-6% but a few hundred metres long. The rest of the journey is flat.
I don't mean to sound blase about the hills, NOBODY likes hills. Sadly they are a necessary evil of cycling where I live.

 

[etriker]

Hi all,
been fascinating reading the forum over the last few days picking up info.
I'm in the UK and looking to dip my toe into the EV water for the first time.

Ultimately I want a system that will let me tow a bike trailer to the beach (about 6 miles each way) with my kayak on it for a bit of surfing.
I want to sort the bike out first though with proof of concept, before I get ahead of myself and attach the trailer to it.

I have a nice new aluminium TT frame which I'm almost finished building into a flat bar cruiser with 3x7 on-road suitable gearing which will be the intended victim for this set-up.
This is what the frame looks like.

obviously this uses 700c roadbike wheels. Specs wise the overall weight of me and bike comes out at around 80kgs plus another 25kgs for the trailer.
I'm not looking to be a speed freak and I'm happy doing some of the work on the pedals. I figure torque is more use to my application than overall top speed.
If I can cruise around 15mph there and back with trailer I'll be a happy camper. It's not overly hilly just a couple around 10% at each end of the ride.
I intend to have a rear rack with some sort of lockable pannier to carry the battery/ies and controller nice and low down. Ideally I want the bike looking as regular bike like as possible rather than some kind of frankenbike.

kit wise I'm spec'ing the following as my starting point.

Rear hub motor around 250w
4qd porter controller, upto 36v and 30a continuous. (will do up to 46v and 40a peak)
thumb throttle
6 cell 5500mah Lipo battery pack with BMS connector (approx 22v)
BMS lipo charger and supply

I figure this will get me into the game but I think with this battery I'm short on the range.
If the concept works well I can buy another pack and presumably parallel it for an increase in range.

Have I overlooked anything critical?
I'm looking at a seven speed rear gear cassette, do the rear hub motor use standard shimano cassette's or do I need a specific cassette?

cheers
Andrew

Why did you decide to use lipo batteries ?

They are the crappiest worst batteries of all.

Lipo on ebikes is for newbees with money to burn ! Junk !

 

[Ykick]

In case you haven't figured it out yet, the ignore feature is your friend. etriker is a very good candidate to ignore IMO. That (bleep) will only pollute your thread while crusading against RC Lipo.

And yes about the TT frame. Do yourself a favor and find something suggested.

 

[etriker]

In case you haven't figured it out yet, the ignore feature is your friend. etriker is a very good candidate to ignore IMO. That assclown will only pollute your thread while crusading against RC Lipo.

And yes about the TT frame. Do yourself a favor and find something suggested.

I am just saying what I wish someone had told me before I wasted my money on HK lipo.

 

[Beachcruzer]

I'm gonna vote against the TT frame too, but not for the same reason as everybody else. It would just be a shame to muddle a nice light frame like that with a motor, rack and panniers. Keep it as a flat-bar cruiser for errands around town and generally hauling ass sans motor. I'd go single-speed (not fixie) geared pretty light--something you can cruise at 80 rpm/20 mph, and still get up those hills.

Back to your project. I'm a kayaker too, so I've got a good idea of the parameters you're dealing with. I also regularly haul my 9'9" longboard to the beach to surf, using this "mule" trailer. http://muletransportsystems.com/news_page.html Round-trip to my regular beach is 14 miles, with rolling terrain and a short steep drop down to the beach.

I use a direct-drive hubmotor (Aotema) running 18s lipo (75 volts) through a Lyen 12-fet controller on my beach bike. The motor is nominally 600 watts; but with that setup it usually draws around 1300. What's that work out to in real life? I usually ride at about 25 mph pulling the surfboard, but I've hit 35 with throttle to spare. That battery pack (6 of the 6s/5 ah bricks wired together) does the 14 miles with just a little bit to spare. I could make that roundtrip on 4 packs (12s/2p) but that would be cutting it pretty fine, and I'd have to moderate the speed for sure. So I would strongly suggest you get 6 x 6s/5ah or equivalent capacity if you choose to go RC lipo. You'd probably want to wire it 12s/3p, for 50 volts hot and 15 amp-hours.

The motor is a matter of preference. Dogman's advice is always good, so take a hard look at the MAC. The 9C or similar direct-drive hubs would also do you fine. Considering that you've got some hills and will be towing a trailer you'll probably want a slow wind motor optimized for more torque. Don't get too hung up about that though. If you paddle a 'glass surf kayak, the thing only weighs about 25 pounds so it doesn't need that much more power to pull. You say 15 mph, but you're probably going to ride at about 25 mph when you get your motor installed. That's just the sweet spot, nice relaxed cruising speed on these bikes.

You're going to have to leave your bike out on the beach when you surf, so I'd look for a frame that nobody is going to go out of his way to jack. Something inexpensive but still cool and fun to ride. I'm into old school beach cruisers for that purpose, and they are easy to electrify. As others have said, an 80s or 90s steel mountain bike with v-brakes can be had for a song, rides like a dream on pavement and packed sand, and is also easy to electrify. Don't put your batteries on a rear rack. Just don't. You'll hate it.

 

[White2505]

cheers for the comments.

I'd considered electrifying the trailer instead of the bike and will certainly look at that again as an alternative option.
Nice to hear from someone with experience of doing what I'm looking to do.
I'd seen your cruiser in your avatar when going through threads a few days ago. Very clean. I like that alot!

I'd looked at lipo as it appears to give very a large amount of energy in a very light package, fairly cost effectively.
the pack I was looking at had the following stats 5500mAh Voltage 6S1P (22.2v) 6cell Discharge 25C all in a small footprint and under a kg in weight.
All for under $120
fully get the safety concerns around them and have facilities for an outdoor charging station if I do go that route. I certainly don't have money to burn!
The nice thing is nothing is set in stone at this point hence why I've come on here for advice. Everything can change if necessary but I need to understand why I'm changing something or I learn nothing and may just as well go and buy an ugly off the shelf model.

The kayak is a plastic playboat which is just over 6ft long and about 12kg. Hence with the weight of the trailer and additional paddling gear I'm estimating an overall trailer weight of 25kg. I hope it will be significantly less than that in reality.
This current bike build as a non ev just need wheels and cables and it's done, looking forward to getting it out on the road. If this one doesn't get ev'd for the experience it's no biggie.

 

[dogman dan]

Yeah, I vote against the frame now too. Bear in mind, once you have that motor, weight will matter less than wind resistance. Go and find a dirt cheap used steel frame MTB, or even a beach cruiser bike with a 7 speed rear gear.

A 500w or so gearmotor will do well enough on that short of a 10% grade. Get one with a slower RPM. Pedal like hell of course to help it up it. After that, 5-6% grades will be no sweat. The biggest problem with that trailer will be if you have to ride home in nasty wind. It sounds light enough, but into bad headwinds tiny gearmotors just bog down.

I do tend to discourage use of lico (RC lipo) chemistry batteries for noobs. Read a lot, and treat them like they can burn your house down if you don't do things right. Once you break the rules, damage or overcharge/overdischarge them, they become VERY hazardous.

And since Etriker is harping on it, don't expect high QC from them. If you need up to 10 packs, buy one extra. You have to sort out the dogs. Then you will spend up to $200 just to charge them quickly and safely. So while the cells might be cheap, the monitoring and charging may not be. You'll need about 1 ah per mile of 36v battery, so it will cost more than you are thinking.

If you feel like it, you could proceed with the plan to electrify that frame with a very small very light 250w gearmotor, and a 10 amp controller, and a very small battery. You'll love it, just forget it as the trailer hauler. Build a more powerful ebike later for that.

 

[Beachcruzer]

If you're paddling a plastic playboat in ocean waves, I'd forget about the electric bike and spend the money on a surf kayak with a planing hull and fins, or a waveski. The playboat is a blast on river waves but to really surf and ride the line you need edges and fins. So if you have the price-of-entry that it would take to put a pretty good hubmotor/controller/battery pack on your bike (about $800 Stateside, and probably a bit more in the U.K.) and if your primary mission is to tow it down to the beach and have a good surf, then put your money into the boat. If however the bike-to-surf mission is merely a good excuse to go electric, then by all means proceed.

The cheapest lipo these days are the 4s 5ah Turnigy hard packs which sell for about $25 apiece from Hobby King. You'd want eight or nine of those, wired 16s/2p or 12s/3p. That would give you plenty of juice. Add $100 charger and power supply, and $50-$100 for harness depending on whether you make your own or purchase from Icecube157. That's about $450 for your pack. Add a motor/controller kit and Bob's your uncle.

 

[White2505]

Cheers Beachcruzer,

had 3 different surf kayaks and loved them all. 8)
We went to one car only in our house about 2 years ago.
I cycle to work and usually only pinch the wife's car if I'm going fishing or kayaking.
Both can be done fairly locally (within about 12-14 mile round trip) but I need a trailer to haul the stuff around on if I'm going totally car free this year.
I'm really tempted to EV the trailer as I don't need the help with my general cycling but figure that it'll become my friend with hauling duties.

 

[Beachcruzer]

Power trailer could be pretty cool. A few people on here have built them I think. Anyway, you've got your priorities figured out--paddle, fish, ride, and leave the car in the garage.

 

[White2505]

LOL, my priorities are set. afterall a bad day at the beach is still better than a good day at work!
However my claims to some sort of eco-warrior status are blown away every time I dig my Motorbike out of the garage.

 

[Beachcruzer]

Yes, but your funhog cred is further enhanced.

 

[dogman dan]

Definitely have your head screwed on correctly. Hoka Hey, you might be dead tomorrow.

You might definitely want to consider a small light battery on the bike, then carry more battery on the trailer for the higher watthour/mile cargo rides. I still vote for the motor on the bike though. And a second bike for non powered rides.

 

[White2505]

I've got a nice roadbike already for tarmac mile munching. This one is just a toy for the fun of building it.
after all the ideal number of pushbikes is N+1 (where N= the number you already have!)

 

[White2505]

okay, my bike build is coming along nicely. The controls are here. I just need the rear cassette to turn up and it'll be ready for cable fettling and it'll be complete.
I've gone for a three x seven speed gear set up using a screw on cassette as this give me the option of an easy hub motor slot in if I go that route.

I'm now thinking through the trailer thing and trying to work out my maths and gearing stuff. Can someone confirm I'm on the right track.
The trailer is supplied with 16inch wheels. Therefore an approx circumference with tyre of 42.4 inches.
A demo motor I'm looking at runs optimally at 3000 rpm. It's fitted with an 11 tooth gear on it.
If I run with something like a 70 tooth rear sprocket on the wheel this gives a gear ratio of around 6.4/1. Therefore for every minute at 3000rpm on the motor the rear wheel is turning 471 times covering 471 x 42.4 inches. i.e. just shy of 20000 inches per minute ( just under 19mph)

Does this sound correct?

 

[White2505]

Okay, bike is built up. currently running on some spare skinnies (23mm) I had kicking around. If I make spacers for the rear wheel drop outs I can just about shoe horn in 35mm touring tyres but it's real tight and definitely no room for mudguards. I shall run the skinnies until they're worn through and then up size to either 25 or 28's I think.
just waiting on the cable ends and some minor finishing parts to turn up and that's the test bed bike sorted.
I'm looking for a cheap cargo cargo trailer for kayak and fishing gear hauling duties. Once I've got that sorted I'll need to make a decision on which bit I'm EV'ing bike or trailer........... or both!