Scroll down to the 7th message, where I describe the change to 80x80x15mm Panflo fans. I selected these because they are not cheap computer fans and spec-out at a maximum operating temperature of 70°C. In addition, they fit between the cooler and VR so that they can be removed more easily in case a fan fails. The 70mm fans fit under the VR and required it to be removed anytime a fan needed to be extracted.

Most computer fans either don't have a temperature spec or are rated at a much lower temperature. I found these Panflos on Ebay and bought them as an experiment to see if they would hold up to the harsh environment. After three months of summer use they are still running, even after repeated washings and rain, so I'm hopeful. I don't run them when wet as they are not rated as waterproof, but you don't need to run them in the rain anyway. Google "Panasonic Panflo" and you should find some sources. A smaller 70x70x15mm fan should work better for this application, but I couldn't find any and don't think Panasonic makes this size. The 80mm works but stick up above the cooler and will require you to make a small shroud to keep air from moving over the cooler, which would make the fans less effective. I searched exhaustively last May for waterproof computer fans but although some appear to be available I couldn't find any that could be purchased in small numbers.

After using these fans through the summer I find that they do work, but won't keep the bike cool forever. They just slow down the rate of temperature rise, which helps.

 

Thanks