Namida12

I am looking to reduce weight on a stealth eBike, would like to know if there are any carbon fiber square taper crank arms that would fit a carbon drive belt drive 130 bcd ring? KBO Stealth Urban Electric Bicycle assembled was 37.7 pounds, I have reduced the weight to 32 pounds, now would like to reduce the weight a little more to make it even easier to carry up and down stairs. An eBike in my neighborhood would last about an hour if I had a removable battery, and a Hiplok D1000 bike lock. I have 3 flight of narrow stairs to negotiate and 32 pounds gets heavy at the end of the day... Could not afford a Ribble 24 pound bicycle, nor a Greg Lemond 26 pound prolog eBike.

Or an adapter to modify a light weight isis or octolink crank arms/spider to fit square taper bottom bracket.

Torque Sensor for eBikes are not that common, but are needed to use small motor for single speed eBike on long inclines and seem to be available for square tapper bottom brackets. There is one isis torque sensor but it seems that unit is not very dependable unit, remainder i know about are for Square taper bottom brackets.

These Hope arms are for an isis bottom bracket will not work in my situation.




JR

Iride01 

It has to be square taper?

BB's don't cost much. Many 18 dollars or less. So if you were willing to change it you might find something.

It's hard for me to imagine a square taper BB today that isn't in a BSA threaded shell and there are all sorts of inexpensive ISIS or Octalink v2 and other BB types that fit in BSA threaded shells.

Namida12

Iride01,

No extras on eBikes if you do not use a square taper bottom bracket, Torque sensor that controls assist power is a square taper bottom bracket extra, that does not exist in ISIS or Octalink bottom brackets. There is one isis manufacturer of torque sensor but its dependability is not good. In the ebike arena small watt motors require Torque sensing, instead of cadence when you need power for short hills, or long gentle inclines where a riders cadence decreases. On cadence sensing when you slow down your pedal rotational speed it is sending info to motor - Oh rider wants less power assist, when in fact you need more power assist to climb the hill, or incline. That is the major reason for a Torque Sensor in eBikes, or having very heavy powerful motors, and large battery with a throttle control. Unfortunately larger motors and larger batteries increases bicycle weight making carrying up and down stairs a difficult endeavor when approaching 35 pounds if you live in a condo, apartment or high rise building without a freight elevator.

I agree, it seems the eBike industry use of Square Taper bottom bracket make carbon fiber cranks difficult to acquire and fit, or proprietary parts if your are one of the large manufactures. If I could afforded the 3x or 4x purchase price of my KBO Hurricane I would have acquired a Ribble 24 pound eBike, or LeMond Prolog eBike and never need to worry about weight reduction. But I am also not one of the potential purchasers to dream of spinning the pedals on the $9,000 - $17,000 specialized turbo creo sl that have entered the eBike market recently.

JR

70sSanO

The problem I see is that if you even find 130mm bcd crank, I imagine it would come as a double and not a single speed.

I read that FSA offered a double carbon crank in the early 2000’s that did not offer much weight savings. I don’t know the particulars, but I imagine square taper BB weight was a factor and that made the high cost design a loser.

I think your first step is to figure out how much your current crank weighs and then go find a lighter aluminum one.

John

squirtdad

It would seem like there would be very little noticeable weight savings..... what do the current cranks weigh and BB weigh? at this point return is going to be minimal. OP has aready reduced weight by 5.7 lbs (would be interesting to see how)

of course las vegas is pretty flat.....going to non ebike would save a lot of weight