Aero Saddle Case / Radar Mount (Garmin & Coospo)

Are you worried about how a saddle bag and a separate radar mount ruin your sleek Aero Bike???

Have you shaved your legs and are you looking for more marginal aero gains?

Look no further, this saddle case design combines the functionality of a saddle bag and a radar mount into a single, aerodynamic, hard case integrated into the seatpost and saddle rails. All mounting features are rigid and outside the airflow.

There are separate models (listed as print profiles) for:

• Canyon Aeroad 2025 SP0077 seatpost (bolt mounted)
  • the Garmin Varia RTL515 Radar 
  • the Coospo TR0070 Radar 
•  Generic Aero seatpost (tie-wrap mounted)
  • the Garmin Varia RTL515 Radar 

  • the Coospo TR0070 Radar

     

The case primarily mounts to the top light mounting hole in the Canyon seatpost SP0077 with 1x 30mm M4 bolt & washer or to any other seatpost with a tie-wrap. The case also rests on the saddle rails, to which you should fixate the “wings” with tie-wrap, this locks in all degrees of freedom (lateral & rotational). 

The volume of the case is about 300ml: it easily fits a multitool, CO2 cartridge / nozzle, Dynaplug set, minor spares for your bike, a spare “locking beam” and a small lock.  I expect you could also fit a a non-tubeless set: a multitool, CO2 cartridge / nozzle and a TPU tube. I recommend to add in a plastic bag wag as filler to avoid rattling.

Mounting instructions: 

• Insert the tie-wrap before mounting.
• Insert the case into the saddle from the back / top → it is easiest to insert the wings of the case where the saddle rails are widest apart.
• Insert the M4 + washer and ensure the front of the case touches / is aligned with the seatpost / or for the generic seatpost, fasten the tie-wrap
• Tighten down the tie-wraps, it is essential that the wings of the case are resting on top of the saddle rails
• Tighten it down the m4 screw and ensure the case is aligned with the seatpost (if applicable)
• Tighten down the rear tie-wraps, but avoid lifting the case against the back of the saddle (there should be a few mm between saddle and case)

Design & print considerations:

• I tried to keep the design as small and light as possible (<50grams), hence the simple locking mechanism and top mount with tie-wraps. Using a screw mount would come at the cost of internal volume of the top section of the design, bigger case, more drag & weight etc. This is an emergency tool pack; aero first, ease of access second, ease of installation third. 
• The tolerances have been developed for ASA printing (I recommend ASA for this application anyway because of the outdoors deployment)
• Special attention was given to the M4 connection point on the seatpost. When the case is not resting on the saddle rails properly (see mounting instructions), this area is exposed to a large torque. 
• Due to the shape of the backplate and the case the use of print supports is unavoidable. These supports for the case are easy to remove. Removing the print support out of the volume for the Garmin mount is a bit more tedious, it is facilitated by 2 holes on the side where you can insert a screw driver / pliers. 

• The “locking beam” principle intentionally has a quite some resistance (you do not want this jittering out under road vibration), this loosens up a bit after a few uses but should remain a tight fit. Use it a few times before going on a ride to avoid destroying your nails getting the beam out!

   

I have run through >25 prototypes developing this and have ridden >1000km with various iterations of the design. It has come at a point where I would love to hear and see what others think of it and how I (or you) could further improve upon it!