Retrorockit
1 kW
bombusint said:Retrorockit said:I'm 66 years old and in the US. I ride urban South Florida which is one of the hairier places to ride a bike.bombusint said:Greetings All
My next project is to convert a Kona Minute ‘barn find’.
The Minute is a mid sized cargo bike, no longer made but of a type becoming increasingly popular.
As an older person in my 70’s (how did that happen!!?), and having had a heart bypass, I am quite particular in my wants.
Please free to throw cold water on these ideas, there is a lot of experience out there when it comes to reinventing the wheel.
My last ebike was a 1000W rear hub drive. All very exciting, especially when the wheel decided to go along the kerb instead of up on to the bike path. I can personally verify that concrete is hard and old men do not bounce! End result was a badly smashed shoulder joint.
Being a cadence type bike the pedals were in effect a rotary throttle, and although it was excellent transport (1,700kms in 4 months), I did not get any exercise to speak of.
So I want/need lower cadence with high torque, with a throttle for start-offs.
Here in NZ it is hilly, and usually quite a distance between towns, so a high power motor and high capacity battery is required.
As it happens a triangular high capacity 52 volt battery from Luna Mate will fit into the frame just nicely.
http://luna-mate.com/triangle-52v-samsung-18650-24ah-pack-high-power-long-range-au/
Murphy’s Law (https://en.wikipedia.org/wiki/Murphy%27s_law) means that any unplanned stop will result in the bike being in a high gear with the pedal in an awkward position, so the throttle, along with a suitable IGH is highly desirable.
Shimano are releasing IGH’s designed for ebikes, so that looks promising, though ratio range does not look exceptional. They have also released the M355 hydraulic cut-out brake levers and calipers for bikes, though they are not available in all markets yet.
Schwalbe Big Apple tyres and maybe a suspension front fork swap should take care of ride. Smashed shoulder joints don’t like bumps.
Which brings me to the motor. Ebike motor de jour seems to be Bosch ,but I don’t really like them. Too noisy and they keep changing them. Plus I want more power.
. Bafang seems to have only OEM torque sensing mid motors.
So I circled round to TSDZ2. The claimed power seems a bit vague. Is it really 750W, or 750W peak, or RMS, or yeah right!
However, I really like the look of the open source software. In particular the ability to set max. power drain so that it can be safer to run the motor over a wider voltage range.
I also like the possibility of a hand throttle for start-off.
However, the threads warning of overheating concern me a bit, but it seems you can’t have internal temp. measurement and a hand throttle.
And ,now I see some comments that the TSDZ2 is not rugged enough for a cargo bike, though opinions seems to be mixed.
My current plans are to buy a kit from https://www.electrifybike.com/#/ with the open source V20 installed, once a stable version is released that can talk to the 850c controller.
That way the conversion can be ‘plug and play’ and I will have all the necessary cable and software to experiment on a spare motor controller I have for my 36V bike, and to learn how to flash the software for my standard bike.
So when will the stable version of V20 be available?
Perhaps we need some more donations to casainho?
Richard
1- Adding a suspension fork will slow down the handling horribly. Not what's needed on a long cargo bike. Get the biggest tires you can fit and get the pressure to 30 psi or less if possible.
An upright riding position takes weight off of the hands/arms. Suspension seat post. Cane Creek Thudbuster LT is the classic, but the Suntour NCX get's the job done at 1/2 the price. If there are no disc brake tabs use the SA drum Brake.
2- I'm not a fan of hydraulic brakes on bicycles. Avid BB7 with big rotors, and sintered copper pads (on old DH racing setup) are simple reiable and DIY fixable. Working just fine on my 35mph road burner. Sintered pads can boil the fluid in some hydro brakes.
3- Shimano has a 5 speed Ebike hub. 1st gear is direct, all others are OD so gear accordingly. Only in Europe/Japan so far. The old Sturmey Archer 3 speed is tough as hell though. Drum or disc versions. Even some with 8/9 speed casette splines for more gear range if desired. Direct drive in 2nd gear.
IGH gets you a wide single speed chain. Wippermann 1E8 is beastly thick.
4- There is a fix for the derailer downshift issue. Shimano Rapid Rise 8-9 speed, aka "low normal".
the shifter lets out cable for downshifts. RD MD951, RD M960 derailers. Medium cage can be found for a 1x drivetrain in XTR group. There were others in XT,LX and Tourney groups. You will need a gripshift, SRAM Rocket or Attack work. SL RS40 is a Shimano Rapid Rise gripshift. Trigger shifters only allow 1 up 3 down shifting and RR is reverse pattern so forget that. The gripshift can dump all gears sitting still. The shift will happen when the bike drives forward ( the chain must be moving). Not as slick as an IGH, But real close. I'm running 50t Surly stainless steel ring x 11-40t Sunrace 8 speed casette. M951 mid cage, SL RS40 shifter.
5- TSDZ2? These are popular where 350W is the legal limit. Like the Bosch and Yamaha stuff. I'm in the US and 750W is the legal limit here. BBS02 and BBSHD are prefered, and TSDZ2 is almost unheard of. They have no cooling to speak of. The driveline was designed for 350w. Luck of the draw whether yours will break or not. Long walk home at 70 years old? In the hills? Pushing a cargo bike? Lots of broken parts in this thread. I have no idea what the inside of my 1500W BBSHD looks like. Riveted Wippermann 8SE chain hold up pretty well. Measure the stretch and lube often. Wheels up 3rd gear launches and 30+mph blasts in traffic are not unusual for me. Silent also. Think BBSHD is too expensive? The only thing that costs more than doing it right the first time, is doing it right the 2nd time. Luna can set you up with it all in one shot.
6- Exercise? I run PAS 1/5 unless there's a headwind or I'm climbing a bridge then 2/5. I find a speed that's easy, then shift up a gear and ride 3-4mph faster at the same assist. I get my exercise, and get where I'm going sooner.
I hope this gives you some ideas. If you use a Wippermann Connex link, carry a spare. I took me 6 months but I did manage to break one. Long walk etc.etc.
Thanks for your input.
Re front shock forks - the Kona Minute is a mid length cargo bike. More of an SUV than a truck. I know of one that was converted to a fat bike with front shocks very successfully.
Re Bafang vs TZDZ2 ... I have used cadence and torque sensing and for me torque sensing is a better experience.
The long wheelbase WILL make it less sensitive to an increase in fork height. Find out, or measure the axle to crown (lower headset bearing) dimension, and try to get a fork that's reasonably close to that. It may also be that cruising around in the country side it's less of an issue than dodging cars at close quarters. If you can get a bike shop to stick a fork in there to test ride it then you will know what to expect before you buy. I made a 1" increase in travel on one of my bikes and took it back off. 60mm to 85mm fork swap.