Cost-Benefit Comparison: Commuter Bikes and E-Bike Conversion Kits

Mike leroy

Active Member
Do you own a Commuter bike that you want to convert to an electric bike? My hope is to avoid upgrading to a motor by using an 11-speed, 400% gear ratio IGH. My fallback plan is use the bus bike rack, if pedaling proves too arduous on my steep hills. If the bus becomes too inconvenient, then an electric motor will be necessary. To verify that this commuter bike can be converted, the complicated details are investigated. Nice introduction to commuter bikes.

15-fairfax-sc6-eq_1152_648_80_s.jpg

The Oregon Manifesto contest winner is Denny designed by Teague x Sizemore. The bike will be sold by Fuji. The Denny design is inspirational and the basis of comparison for a well-designed commuter eBike.


The basis of comparison from the Oregon Manifesto Mandatory Features. "Without exception, all entry bikes must possess the following useful features:
  • Anti-Theft System: System should prove to be secure and easy to use.
  • Lighting System: System should aid rider vision and provide high visibility on the road.
  • Load-Carrying System: Entries should be able to carry a variety of loads through a variety of conditions. System should accommodate a typical user load, such as a bag of groceries, commuter or gym bag, etc.
  • Free-standing Under Load System: Bike must free-stand under a variety of loads on a variety of surfaces.
  • Fender System: Fender system must keep bike and rider clean.
  • Road-tested: Bike should be road-ready and tested. The team-produced video should include brief footage of the bike in motion on the road (including hills), carrying a load and in use during typical real-world scenarios."


The closest, unpowered bike that I found is the Marin Fairfax SC6 DLX, equipped with a Gates Carbon Belt Drive, rather than a conventional chain. I found the Shimano Alfine 11-speed combined with a belt to be a very complicated EBike conversion. So complicated, in fact, that I felt compelled to document the details. I am not entirely certain the conversion is wise or possible due to the 68mm eccentric bottom bracket used to tension the belt drive. A further complication is the Shimano 41mm chainline length. How to correctly shim the chainline to 50mm needed by the 8Fun BBS02 center-mounted motor is unclear, or perhaps not possible.
"The Fairfax SC6 offers riders a unique option for commuting with a simple, higly durable, super low-maintenance, and versatile Shimano Alfine 11-speed internal hub drivetrain and Gates CenterTrack Carbon belt drive. Additional amenities like lightweight extruded aluminum fenders and a Super Nova E3 lighting system powered by a front dynamo hub provide powerful battery-free illumination for night riding. To conquer the road ahead, quality components like Shimano T445 hydraulic brakes and aero-profile rims with puncture-resistant tires provide sure-footed tracking and control. Combined with the lightweight highly formed and butted Series 3 aluminum frame and carbon fork which offers full rack mounts, the Fairfax is guaranteed to deliver you to your destination fast, and in style."


Series 3 Frame with 3D forged dropouts with integrated post mount disc brake mounts, rear mounted kickstand attachment, and dual eyelets for quick and easy fender and rack mounting


Some questions that will be resolved:
  • Is the carbon fork strong enough for a 750W electric mid-mounted motor? Carbon design provides flexibility to dampen vibrations.
  • Will a dry and dusty metaled fire road cause excessive wear on a carbon belt?
  • Can the Alfine-11 withstand 120Nm of torque generated by the BBS02 motor?
  • Is the Fairfax 6061 aluminum frame strong enough for the BBS02 motor? "the lightweight highly formed and butted Series 3 aluminum frame"
  • What is the best frame splitting technique for Gates Carbon Drive and electric motors?
  • Is an eccentric bottom bracket, or Vertical sliding dropout the best belt adjustment mechanism for a center-mounted bike?
Gates only recommends vertical sliding dropouts or EBBs for Carbon Drive compatibility. Unfortunately, the BBS02 BB replaces the Fairfax eccentric BB, which is required to adjust belt tension.

The Spot ACME may be compatible with "newly designed Wagyū 2 Slider Dropouts allow belt-driven or chain-driven configurations, and painless wheel removal with no need to re-tension the belt.". Spot is owned by Gates. Spot uses both EBB and a horizontal slider. I am not sure if the EBB is required.

The Surly Troll or Ogre has a horizontal sliding dropout, which is not Gates recommended.

Palo Alto Bicycles sells Spot, Surly and other related bikes, so I will probably buy from them. I love Pinion gearbox.

The Raleigh Misceo 4.0 I8 fire trail orientation fits me perfectly. Unclear whether the Alfine-8 can be upgraded to an Alfine-14.

The BBS02 chainline is 49mm. The Alfine-11 chainline is 41mm. A Rohloff-14 is needed to replace the Alfine-11, so the chain lines align. Comparing costs is the next step. The short-term, low cost solution is the Alfine-11. The long-term, low-cost solution is custom building with a Surly Ogre frame and a Rohloff-14 IGH. If you are confident you will not need a motor in the near future, then the Spot ACME or Marin Fairfax may be the most cost-effective solution.

There may be more details to consider. For example, The Marin Fairfax will not work because the Eccentric Bottom Bracket conflicts with the BBSo2. The walls of the BSA bracket must be 68-73mm in width and 35mm inner shell only. The Spot ACME is not Rohloff strength approved, so I do not want to risk putting a powerful motor on it.

My choice is to put the $1700 MSRP Surly Ogre on the bus rack, if the hill is too difficult with 35 pounds of groceries. This Price point reaches the point of diminishing returns for me. The Ogre bottom bracket supports a BBS02 mid-mounted motor. A Rohloff IGH can also be added. Only the Gates Carbon Drive is excluded because the frame is not pre-split.

If you are looking for a CA M2 Scooter equivalent, I believe the following are compatible. The key is rear brakes, which are limited to 160mm rotors.
  1. 1500W BBS02 center-mounted
  2. Surly Ogre
  3. Rohloff-14 IGH
  4. Magura MT-5 or MT-6 brakes

(Link Removed - No Longer Exists) (Link Removed - No Longer Exists)



 
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Mike leroy

Active Member
I research and write articles in fits-and-starts, as my spare time permits. Writing an article usually takes one full week. So, check back regularly.