Cratus Short SRM Origin Crankarms


SHORT VERSION 145-160mm.

Bringing maximum aerodynamics to your SRM Origin powermeter through a narrower Q factor, CFD optimised crankarm profile and adjustable length crankarms.

Available in both short and long versions, allowing adjustment in 2.5mm increments between 145-160mm and 160-175mm respectively.

If required additional pedal insert sizes are available separately.


Product Description

The hugely popular SRM Origin is a commonly used crank across both road and track disciplines. With a Q factor of 145.5mm; our Cratus SRM crank arms reduce this by 8.5mm. Reducing the Q factor to 133mm on track axles and 137mm on road axles.

Manufactured from 7075-T6 aluminium, anodised black and subtly laser etched with WattShop branding.

These crank arms are only compatible with the 30mm, 29mm (DUB) or 24mm spindles. The latter when using the 24mm to 30mm spindle adapter. They are not compatible with the SRM Track Science (Octalink).

Additional pedal insert lengths can be purchased separately.

PLEASE NOTE if you are proposing to use with a 2x crankset we recommend double checking your front mech clearance.

Technical Specifications


The 8.5mm reduction in Q factor equates to a rider dependent saving of 0.0009 to 0.0017m^2. Assuming a standard air density of 1.225kg/m^3 this results in a saving of:
- At 50kph = 1.5-3w
- At 60kph = 2.5-5w


- 160-175mm Arms = 581g
- Pedal Inserts (inc plates) = 75g/pair


- DS & NDS crank arms
- 2x upper barrel nuts
- 2x lower barrel nuts
- 2x M5x25mm cap head bolts
- 1x M6 split bolt
- 1x pair of pedal inserts and plates

Customisation Options

Fixed length options can be made to order. Please email with your custom requirements.