Originally Posted by
MarcusT
I appreciate the replies, but I don't believe we're talking about the same riding. When I say mountains, I mean 1,000 meter climbs of trails and fire roads. 20-25% grade. 42X36 even with a motor is not going to cut it. Maybe 28X36
KPREN, you say it's geared down. Can you express that in gear inches?
Cheers
Maximum chainring speed on the Bafangs is about 130 rpm. The motor itself is turning around 5,000 plus rpm.
Everyone here is right about the chainring size. You can go below 42 teelth. If you do, your chain line will suck and you will have short drivetrain life and may not be able to run high count cassettes. A Bafang will do it regardless of what you may think.
I am running a Big F
at Titanium bike with a BBSHD setup with an 11 speed drivetrain. I have a 42 tooth Lekkie chain ring and 11X46 cassette. I am running 4-52 volt batteries in parallel for a total of 2,538 watt hours. The only time I get into the cogs above 36 are when I am climbing at very low or no power applied. My bike weighs 82 lb and I weight 200 lb. I often pull a trailer up to 150 lb.
On this bikepacking trip I was pulling 25% grades