I have spoken with some BBS02 users who believed that the stock crank arms that come with a BBSxx kit have a soft metal and therefore prone to working themselves loose. They recommended crank arms designed for the Shimano STePS. Do others feel that these crank arms would benefit from replacement, or is it more a problem of improper installation? Are the stock crank arms on the BBSHD the same as the BBS02?
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BBSHD crank arms: How heavy duty are they?
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I weigh about 190# and my BBS02 crank arms were both destroyed within 120mi. on the odometer.
I have never previously destroyed a crank arm on any bike I ever owned. I cut the chainring mounting spider off of a Specialized right crank, sanded, buffed, Cerakoted it Graphite Black. Mounted up those FORGED cranks, and expect them to last forever.
They are slightly more offset, but I can barely notice.
I think the damage happen when the pedals impacted sidehill rocks on single track. But all my other cranks survived that abuse for years.
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Another avenue I'm considering, is using a thread repair kit with steel nutserts. Since my friend and I have built several "power bikes", both gas and electric, we have stripped out the pedal threads on a bunch of cheap import cranks. The thread insert kit is $111 on Amazon, and comes with 6 inserts for each side, and 2 special taper-reamer-taps.
I really think using red locktite to install those would make a long lasting pedal thread repair.
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I pre-emptively replaced mine with these Schlumpf 170mm crank arms in silver (because they were way cheaper for some reason). I haven't been able to find any specifics on what they are made from, but maybe stainless steel? (I'm only guessing that because there is a stamp on the inside edge that says SSTL)
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Unicycle cranks are steel and cost $15 a pair....... They also come in all sorts of lengths from the standard 170/175mm down to under 100mm! I have a couple of different sizes and haven't had any problems.
Last edited by Lance Tesla; 04-06-2016, 10:42 AM.
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I can't imagine ever using long cranks on an ebike again...... A pair of 147s will let you spin faster and allow you to more easily keep up with your mid-drive. The long arms are great for putting the highest torque into a pushbike, but a BBSxx has lots of torque for most needs, it just needs a bit of help over the very worst terrain. For this, short cranks let you spin a smaller circle at a faster cadence letting you keep your drive in the higher rpm ranges where it is the most efficient.
When I had my crash I was swapping between 147mm cranks and 120mm, the shortest ones felt strange at first, but soon seem "normal" and there is certainly no issue with pedal strikes! One caveat: I ride 99.99% of the time in PAS and very rarely ever actually pedal (put torque into the chain) simply slowly rotating my feet to keep the PAS activated. I don't ebike for exercise, but instead see it as way to get outside and into the wilderness with as little effort and noise/impact as possible.Last edited by Lance Tesla; 04-08-2016, 08:22 AM.
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Originally posted by paxtana View PostI have spoken with some BBS02 users who believed that the stock crank arms that come with a BBSxx kit have a soft metal and therefore prone to working themselves loose. They recommended crank arms designed for the Shimano STePS. Do others feel that these crank arms would benefit from replacement, or is it more a problem of improper installation? Are the stock crank arms on the BBSHD the same as the BBS02?
The BMX people have a huge range of square drive cranks. I fitted 145's on my wife's recumbent tadpole trike with a BBS01. I left the spider on, looks great. It's one way to get a higher cadence to keep up with the motor1 Photo
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