After about a month and a half of obsessive research, I took the plunge on one of the Grin "Ready-to-Roll" kits for my folding bike. Before this decision, my choices had been floating around 3 categories of kits:
1. Genteel grampa kits: Leeds. These 8Fun hub kits were my first choice for ease of installation, cost, and name brand cells in their batteries. Cons:the 250 watt motors that drew in me are likely to start feeling underpowered in my hilly part of Manhattan. Leeds' conversion philosophy centers around staying in their ecosystem and not asking too many questions about componentry. Upgrading or branching out would be hard. The Australian company Dillinger had interesting kits but their options for 20 inch wheels were lacking.
2. All of the Bafang BBHD or BBS02 mid-drive kits floating around the internet. Cons: I may try my hand at mid-drive in the future but, outside of Luna, the sourcing for these kits are kinda murky. Ultimately, the Q factor of the cranks--that they "stick out" further horizontally--would be tricky for my low sitting folder on fast turns. I still want to ride my bike like a bike!
3. Grin hub motor kits. That they have an actual 75mm front hub motor, Crystalyte SAW20, first drew me in. I currently really like how my bike handles and don't want to radically change much, so the Crstyalye is basically the only hub option. The rear, alloy dropouts of my bike is 130mm, so I didn't want to chance trying to spread out for the standard 135mmm motor hubs. I've used low panniers on my front 20" wheel and when it's weighted down, it really beautiful cancels out the "twitchiness" of Dahon forks. I expect that the front hub will have the same effect.
Bikes, parts, and components:
- Dahon Vigor all aluminum folding bike.
- Crystalye SAW20 direct drive front hub motor laced to narrowish 19mm inner diameter wheels
- 1.5 inch Scwhalbe Marathon tire in front to puncture protection, 1.75 inch more subtle Schwalbe Road Cruiser in the back. I had these on hand. I typically use narrower, slick tires and any type of traction feels like molasses to me but addressing flats with a wheel that is attached at 3 places and bolted to torque will not be like my current quick release set up.
- Two Grin torque arms for both sides of my aluminum fork. My conclusion has been that with proper use of torque arms, my riding style (never really much over 15mph), and the relatively low power of this motor, the alloy fork won't be much of an issue. I plan on keeping a close eye on it in any case.
- Touring-grade 20 inch rear rack (made by Tern) and 300mmx35mm DiN rails for mounting the battery cradle onto the rack. I've seen others mount dolphin/Hailong downtube batteries to Dahon frames but I feel anxious about mounting an 11lb battery this close to the hinge of the fold.
- 36V 26.5 Ah batter and Z9 Baserunner both chosen because that was the biggest battery the kit can come with! These are already expensive, so I just picked the one that would last longest in terms of single trips and charging cycles. https://ebikes.ca/shop/electric-bicycle ... ttery.html[/url]
Actual Weight (kg) 5.18
Dimensions (L x W x H, mm) 370x89x137
Nominal Voltage 36 Volt (10s)
Full Charge Voltage 42.0
Capacity (Amp-Hours) 26.5
Cell Type Panasonic NCR18650GA 10S x 8P
Internal Resistance (Ohms) 0.06
Aside from anxiously waiting for the rest of my kit to arrive (the battery itself was basically teleported to my apartment in a few days but the rest is currently moving across the continent) and pouring over the CA manual, any tips for preparing for this build?
Looking forwarding to posting my progress and pictures. Many thanks for all the contributors to this forum. I've really learned a lot from the generosity of this community. I hope to post what I learn about converting low weight folding bikes, particularly for those who lack space and require something lighter than commercial folding ebikes offer. (There are 4 flights of stairs to my tiny apartment and I have the physique of a university administrator, not a bodybuilder, lol...).