Hello and welcome to my cosy little project thread. Since the 2nd gen Tangents are here, I'm finally ready to start my second e-bike build. Right now, i'm trying to decide what parts to buy and how it all fits together. I will do my best to document my efforts here in as much detail as possible for two reasons:
1. To help others as endless sphere and the community helped me and
2. to hopefully be made aware of mistakes/dumb things i do before they become dangerous or expensive.
I'm happy for any advice, ideas, anything that might help me get my build done. Please beware that i'm in Germany, so sourcing special parts from america/Canada isn't exactly easy. Allright where do i start? Well i think the first step is describing my current build, the problems i had with it and my strategies on mitigating them with the new build.
My current bike is a 29er MTB with a BBS01 that has rougly 3.5k km on it commuting through streets, mud, rain, basically everywhere i wanted to go. While I do love riding it, here is a list of failures/problems/annoyances i've encountered with it that i want to fix in version two (i may add more to this in the future):
* No rear suspension. Nothing like getting kicked in the butt by a small curb when riding at 35 kp/h...
* Power, or lack thereof. 250W is, at no point, enough and my choice of battery can barely support 350W continous.
* Gearing, with only 250W and with a lekkie 42t chainring in the front and a 36t chainring in the back i still find hills i can't climb. Recently i blew my clutch due to this.
* Reliability of the drivetrain is meh. After many fixes i found something that holds up but i want something that does a lot less unfixable breakdowns. So far i've killed a controller, a clutch, had water damage (multiple times), had derailleurs break, etc. I definetly want to build something that's as bulletproof as possible in that regard
* 29er wheels are just to big. Especially when carrying the bike down stairs or in sharp corners. I'm eying a 27.5er
* normal tubed wheels are too succeptable to flats. Going tubeless for sure
* The battery is annoying to remove from the frame. Since im always riding with a backpack anyway, i might aswell get a backpack battery thats easy to remove
* weight: The bike is just too heavy. While driving it's not a problem but it's again a huge pain in the butt to carry down stairs etc.
* no integration of the lights into the main battery. it sucks so bad, when the lights go of while the main battery is still full.
* too wide bars. While it's nice driving with them, i just can't get them through doors/narrow gaps.
* Motor hangs down to low, giving bad clearance. Definetly want the tangent as high up as possible, likely in the frame if possible.
* hard to fix things, especially in the motor due to bafang design and general lack of tools.
* Lack of good maintenance. mostly due a lack of the right tools and lack of experience.
With that in mind, I've been planning a second bike for over a year now, calculating, weighing options, saving money etc. It has been rather clear for a while now that i want a tangent from dave. It's just too much awesomeness packed into a beautiful piece of machinery and the rest of the components will be chosen to fit the tangent. I want to build this entire bike from scratch over a period of about 4-5 month, aquiring parts and tools as necessary. This way, I hope to not only have a tangent e-bike at the end, but also every tool necessary to fix, maintain and modify it as needed. I'll probably not be able to be in the first batch of the tangent gen2s but i think my goal of getting serial -#0042 should be realistic from a timing perspective
Allright so here are the main parameters for the new build
* Torque-y AF. I want the limit of climbing be the grip of the tires, not torque or motorpower.
* Speed: Actually not too much. 50kp/h on the flat with the battery (likely lipo) at ~3.5 volt/cell (so almost empty) as a top speed should suffice but i want as much acceleration as i can handle.
* Range. 30km should be fine. Looking at 1kwh in Lipo in the backpack so that should be attainable even when going uphill at a decent speed.
* Driving profile: Commuting through the urban jungle, though I've learned to stay away from big streets and take the hidden routes. I want to build a "go anywhere bike" wether it's through streets, mud, forests, grass, gravel, basically everywhere where there's remotely a path to take. I'm not looking for jumping more then a curb or a few steps at most but i will take on some serious elevations and lots of gravel path.
* Stealth: Reasonable. If you blast down without pedalling at 60 kp/H down the road there's nothing stealthy about that. But at lower speeds and powers, i think a tangent will be silent enough and when off road, away from streets, people or police i can be a hooligan without issues. Wearing a helmet, a high visibility vest and beeing considerate has helped me stay under the radar so far...
* Weight: I want to be able to carry the bike without a battery up a flight of staris with one hand.
Allright, so here's what i've been thinking:
Motor: 6KW Tangent. Why? POWEEEEEEEEEEEEEEEEEEEEEER! Wether it's going to be a 20:1 or a 40:1 reduction is not clear for me right now. Intuitively, I'm more looking into a 40:1 variant but it will depend on the overall gearing.
Frame: The nice people over at http://chinertown.com/
have got plenty of info on getting good carbon frames from china. There are several options to chose from. I'm mostly looking into carbon because it's available at almost the same price from china as a comparable aluminium frame would be here in germany and there are a few vendors that have been deemed trustworthy by the community. It's a bit of a risk of course but with a carbon frame/carbon wheels i can get down the weight a shitload. I'm looking for something in the all-mountain to enduro range (140-160mm travel) which should be a huge upgrade from my current 110mm front shock only in my BBS build. I've yet to bottom that one out so the additional travel should be plenty, even with 140mm.
To be specific, these frames are in closer consideration, though nothing is set in stone just yet:
Ican p9 Enduro ~200 mm travel
CS-336 All Mountain ~150mm travel
Battery: I haven't found an 18650 based Battery for this project that really hits all the marks in terms of power/C rate. It seems that the BMS is the main limiting factor and without a BMS i might as well go for multistar lipos. I've done plenty of research into safely handling them and with a diy hardcase and padding in a backpack. I have some ideas for the wiring but those can wait until the basic components have been chosen.
When the frame is chosen, most parts become obvious by necessity, the only thing i'm really struggling with is gearing for the tangent. I would love to hear your ideas given my parameters first. I think even a single speed could work with a 40:1 tangent gearbox and the comperatively low topspeed. This is the main issue in all of this i think and I definelty am open to suggestions and ideas here. I don't feel like an open gearing with a deraileur system will work for me since even my bbs01 chews gears like a fat kid in a candy store. Can't imagine a tangent beeing anything but a lot worse with that. Another option would be a rohloff IGH though the price, lack of beeing able to fix it on my own, and the weird mounting with thru-axle wheels makes it not my first choice.
Allright this has been a wall of text already. I think i'm gonna get the first round of feedback at this point, answer your questions and refine the component selection, especially the gearing question and the frame (duh!). I intend to start ordering the first parts in february, depending on dave's status and wether i can decide on the right frame for the build. Given the delivery times that are to be expected, building should start in march-april and i hope to have something driveable ready in may. I'm looking forward to the project and working with everyone here on endless-sphere. Please feel free to comment on any of my choices and suggest alternatives (except the tangent
) I'm happy for all the input i can get!