Ooh, the choice paralysis of DIYing

Hi All,
I'm slowly building a DIY Mongoose Fireball (hardtail) in various stages and I've become a bit parallelized in which way to go next. So far I've got a cheapy 250W rear hub kit on it to get used to the technology but clearly it doesn't have the power I'd like. 750W or 1000W is probably closer to the mark. I've been researching mid drives and fancied the TSDZ2 due to it's smoothness of torque assist but since I've been reading Grintech articles I see a lot of conflicting information. Like front/rear hubs, the size of a valid front hub. Torque assist options for hub drives seem doable etc. Anyway, here's the requirements I'm working to. I realise I'm going to have to compromise somewhere and nothing is perfect.

• When lockdown is over I have a 20k round trip commute.
• I like the occasional forestry hooliganism (even though I'm 49) so mid drive is attractive.
• The smoothness of the TSDZ2 is attractive but I'd like to throttle coast often (35-40kmh). I can't find any info on how good the TSDZ2 is on throttle only.
• My commute is mainly flat. So a decent hub drive would suffice. be cheaper, lower maintenance.
• I like to customise and play with wheel sizes, 20" plus size.
• The BBS's look better for throttle coasting but they are expensive and appear high maintenance.
• I don't like fscking about with chainlines.

I think the clincher is the TSDZ2's throttle only coasting ability. Mid-drives, while higher maintenance and involves more chainline nonsense, seem to tick more boxes but after reading Grintech there's something attractive about just chucking a big hub on it as well. Any advice?

Most 250w kits can handle way more than 250w. The Q100H for example is fairly universally regarded as safe to around 800w, and some, including me, running it at 1100w with just additional oil for cooling.

I'll have to admit that right now I am in a "let's not spend if we don't have to" mentality, which may be colouring my opinions (My job is safe, but my wife is looking down the barrel of a redundancy). But here goes:

1. The only criteria a typical 250w geared (assuming geared) hub will not be ideal for, is your forestry hooliganism. Geared hubs hate sudden changes in resistance, so if you gain air or spin the wheel and suddenly grip, you can break gears.

2. If you don't like maintaining chain lines, you can consider either going belt drive and/or internally geared hub. With an IGH, you can use a much thicker chain - Possibly even a non-bike chain which will be far more durable than one designed for a high gear count deraileur. Remember that with power assist, you need far fewer gears. While I don't have personal experience with a mid drive, since I've switched to a torque sensor, I've been happy with just 2 gears,and one that will get me to 45km/h, and one that will let me climb a 9% grade at high 20s without me feeling the motor will overheat. It may be possible to get away with a single speed if the forestry bit is as flat as your commute.

If you have someone near you that you can borrow a 1000w controller from, you might want to see if your existing setup can be upgraded very cheaply.

If that's not suitable, then as they say, you can have it cheap, reliable, and powerful. Choose any 2. Pre-coronavirus,I would have picked reliable and powerful. My dream ebike is something like a BBS02 or BBDHD with a 3 or 7 speed internally geared hub using a belt drive. The cost of that on a decent frame and a good battery however, would rival a mid-range motorcycle.

‘Forestry hooliganism’ does require large wheels and lots of power if it is a hub build, so big hub, powerful controller, and good FS frame ideally. A BB drive is fine if the build is light weight. A left side mid drive can be much more powerful than BB drives, and geared for higher speed.

40 mph on a hard tail bike can quickly turn into an uncontrollable rodeo. That speed is only safe on nice paved streets, unless you have adequate full suspension to take the hits.

45kmh, not 40mph. Forestry hooliganism is pretty occasional and is really secondary. Think more gravel tracks with odd whoops. There's a few hills and I just bash up them with my 250W currently before my legs give out.

Who makes the Q100H's? BMS Battery and PSWPower both seem to sell them, it's really quite difficult to tell who manufactures what in this scene. My current hub appears to have a round bafang connector on it. I guess this is some sort of standard? Everything else (controller, brake levers, display etc) is all hard wired together. No idea of the specs on the actual controller. I also see BMSbattery sell a mid-drive called QM02 which I hadn't heard of before. Again, no idea who actually makes it.

I was kind of expecting to replace the whole lot at some point but if I go hub then I suppose I can upgrade controller and battery to 48/52V first and see how I go. Then get another hub if needed.

Are the connectors between all these things reasonably standard?

Sorry. Mph is so commonly used on ES, that sometimes we misread. And, 40Mph being the speed I like to ride mountain trails, it felt just natural.

If you're just starting out, you need to understand that Ebikes are addictive. If you get a taste for it, you will build several. There isn't really a "maybe" to it.
So plan your first bike like it was always going to be a "First" bike. Keep it simple.

Since you plan to commute, let me ask you how important is it that you arrive on time to work, every time? The less complicated you make the bike, the more reliable it will be.

A basic 1000w rear mounted direct drive hub motor with a 48-52v battery is as simple as it gets. there are no gears to burn up, no chainline to mess with, very few things to go wrong. Direct drive hub motors are as close to bullet proof as it gets. And after you get the bike dialed in and riding well, you can start to modify it, experiment with different ideas. Like switching to a sinewave controller for an even quieter ride. Adding a Cycle analyst for more programability. Adding more battery for more speed. You can add pedal assist if you want, and there are many different ways to do it.

Once you have rode bike 1 for a while, no matter how you choose to build it, you will find things you wish to change, things you could have done different. other ideas you want to explore. other uses for the bike you never really considered. When you've modified bike 1 as far as you can, and got it as dialed in to make it the best it can be, That's when you will start planning Bike 2.

I totally agree about the addictive nature of DIY Ebikes.

For my first build I went with the TSDZ2 mid drive and took my chance on chain lines and bottom bracket fitment by close inspection of photos of bikes online and referring to manufactures specs (this was a lockdown build).

I wouldn’t hold out too much with the throttle drive as this cuts out around 6-7 mph. I imagine it may be possible to increase this with open source firmware. I’m using the stock firmware which I’m more than happy with after removing the speed limit.

Chain line for me worked out perfect and I have no problem with a ten speed setup.

Link to my build video below.

https://youtu.be/MgUX0FacXfQ

Already planning to fit a CYC X1 pro Gen 2 mid mount drive to my 8 year old Whyte carbon hardtail

Building the first one simple does make a good start. You can ride it very long after you had built a 2nd, use it as a back up, use it as a guest bike, or winter bike when you want to keep your newer build clean. I have built many over the years but still, the first had kept busy very long before I got rid of it for lack of space in the garage. It was a 45 mph commuter and dirt bike, hub built on a Norco A-Line. So many friends had used it, who finally built their own. When I finally sold it, it had done 45000 miles wearing two DD hub motors.

Thanks folks. So my first build is built (as I described in OP). While musing over frames, hubs or mid's, battery mounting, shipping costs to Aus and generally drinking too much, I think my next step is to get a 48 or 52v battery and decent controller and display. Since my current setup is all hardwired together apart from the motor I almost need to start again. I think if I run 48v on my 250w hub it's only going to draw what it needs and the rest goes to waste right?

No, it will draw all it can, which is why the bike has a controller, to control that. Motors will pull till they fry, under a good stiff load.

Controller might work on 48v, or not. It may just refuse, due to a high voltage limiting shut off. Or it might go pop, as low voltage capaicitors inside blow with too much voltage. Or it may just run with enough wattage to melt your motor, under higher load conditions.

My advice would be to go with a typical 48v 1000w kit, if on a budget, and spend the real money on a very good 48 or 52v battery. You might find the 27-30 mph, and up to 1500w peak, plenty.

Mid drive, IMO, is for specialty situations. Higher than normal loads, whether from hills or excess weight.

Thanks for the replies everyone. I think in the interim I'll just cruise around on Build #1 while learning more and scoping out a frame for build #2.

What you COULD do is go right on cruising on build #1 as long as it takes to be building not just a better bike, but the one you'll love this time. https://www.ebay.com/itm/Electric-Bicycle-Bike-Frame-Kit-Stealth-Bomber-Electric-Bicycle-eBike-Frame/223609867251

The idea is you probably won't hate the one you have, so you might as well build something seriously new so you won't miss the old one.

By all means, don't get paralyzed, just buy stuff as you can afford it, and keep building DIY. Its so fun! While I was pretty broke for a decade or so, I just kept sinking my tiny fun budget into it. That budget started out at the cost of a tank of gas a week, plus car repairs on a wore out, nearly dead car, which I was saving by e bike commuting. It amounted to about two hundred a month, and half of that was in the fun budget, the rest paid down some debts.

mongrol said:

Who makes the Q100H's? BMS Battery and PSWPower both seem to sell them, it's really quite difficult to tell who manufactures what in this scene. My current hub appears to have a round bafang connector on it. I guess this is some sort of standard? Everything else (controller, brake levers, display etc) is all hard wired together. No idea of the specs on the actual controller. I also see BMSbattery sell a mid-drive called QM02 which I hadn't heard of before. Again, no idea who actually makes it.

Click to expand...

I think the QM02 is made by qsmotor.com