Stumpjumper PRO 2018 fattie. Maybe build and general questions.

Trigen

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May 28, 2022
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Hey guys!

https://www.specialized.com/us/en/stumpjumper-pro-29-6fattie/p/129072?color=240009-129072&fbclid=IwAR2MFMudfJjGy7M0UF5iethz4EIF4Od57pfz-hybNjrjV7LkboMoOz7N8bU


I just got a Stumpjumper PRO 2018 fattie 29/6 that im thinking about going electric with. Its not a great bike to do electric, at least not with bafang but i got a really nice deal. I have to go backpack battery. I got a guy that specially orders BB02S 250w motors with 900w nominal and only slightly less powerful than a 750w and more efficient but since the frame is such that it needs to hang more or less straight down im a bit worried about the clearance. Maybe i should go with a inside frame motor like this instead https://www.lift-mtb.com/accueil-faq-english/motor-inside-or-outside/ Does anyone have any experience with either?

Also the bike has a PF30 BB so i assume i will need a https://lekkie.tech/product/lekkie-pf30-bafang-adapter/ ? Could i just 3d print this? Would PLA be strong enough over time? Its quite hard when you oversize a bit and press things in but with the added on off it could get loose over time

Any other items that are good? I might not always want the battery either so perhaps a 40 tooth Lekkie ring? i believe it has a 30T on there now.

Any help starting up and making it as easy as possible is great, Im tech and practically minded though
 
Trigen said:
I just got a Stumpjumper PRO 2018 fattie 29/6 that im thinking about going electric with. Its not a great bike to do electric, at least not with bafang but i got a really nice deal. I have to go backpack battery. I got a guy that specially orders BB02S 250w motors with 900w nominal and only slightly less powerful than a 750w and more efficient but since the frame is such that it needs to hang more or less straight down im a bit worried about the clearance.
What specifically do you want the bike to do for you, under what riding/terrain/weather conditions, at what speeds, for what range? You need to determine these first, before you buy anything, to be sure you get parts that will do what you want without being stressed (or even capable of doing it at all).


Also the bike has a PF30 BB so i assume i will need a https://lekkie.tech/product/lekkie-pf30-bafang-adapter/ ? Could i just 3d print this? Would PLA be strong enough over time? Its quite hard when you oversize a bit and press things in but with the added on off it could get loose over time
Will the plastic take repeated pushing down on it from pedalling forces, potentially thousands of cycles a ride? Along with the similar cycling forces on the right from chain tension pulling backwards? If not, it's probably not a good choice. ;)


I might not always want the battery either so perhaps a 40 tooth Lekkie ring? i believe it has a 30T on there now.
What gearing (front and rear) do you successfully use on your regular pedal-only bike to do the same job, vs it's wheel size? This will tell you what gearing to use on this bike to do this job.


Also, there is the http://ebikes.ca/tools/simulator.html that you can use to do basic simulations of various bike / motor / battery / controller setups for your specific riding style and conditions, to see what it will really take to do what you want.
 
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