A narrow-offset e-bike crank built for Bosch SX, Brose S Mag and TQ HPR50 motor systems — forged and CNC-finished alloy at carbon-adjacent weight, in e*thirteen's Bronze or Black finish.

Highlights

  • 21.5mm offset, built for Bosch SX, Brose S Mag, TQ HPR50 (e*thirteen also lists it for Avinox and Specialized 2.2/3.1)
  • 24mm ISIS spindle with built-in self-extracting crank bolt
  • 155mm and 160mm lengths in this listing; Bronze is offered only on the Bosch/Brose/TQ fitment
  • Tested to e*thirteen's E-Enduro standard, EN17406 Class 5
  • No bottom bracket or chainring included

Built for e-bike torque

The 21.5mm offset keeps a traditional MTB Q-factor feel while clearing the motor and chainstay on Bosch SX, Brose S Mag and TQ HPR50-equipped bikes.

Compatibility & fit

24mm ISIS spindle (mounts into the motor's drive-unit interface, not a separate frame bottom bracket), 21.5mm offset. No bottom bracket or chainring included — pair with a Helix Race e*spec direct-mount chainring (sold separately) and service with the ISIS self-extractor bolt kit (CSS40-107).

Options

LengthColour
155mmBlack
160mmBlack
160mmBronze
155mmBronze
e*thirteen covers this product for 10 years against manufacturing and material defects from the date of purchase; crash, impact or misuse damage qualifies for a discounted replacement under e*thirteen's Infinite Ride crash-replacement programme. This is in addition to your rights under the Australian Consumer Law, so keep your proof of purchase. For warranty support, return the product to Tune Cycles and we'll manage the claim with e*thirteen's Australian distributor.
  • 21.5mm offset for Bosch SX / Brose S Mag / TQ HPR50
  • 24mm ISIS spindle, self-extracting bolt
  • 155mm or 160mm, Black or Bronze
  • No BB or chainring included
Offset21.5mm
Spindle24mm ISIS
Motor fitBosch SX, Brose S Mag, TQ HPR50 (also Avinox, Specialized 2.2/3.1)
RatingEN17406 Class 5
Chainring / BBNot included — sold separately
Length / Coloursee Options — 155mm or 160mm, Black or Bronze
SKU DTW-ETG-CS4HAA-1-PAR
Brand e*Thirteen