Any way to convince your work to provide covered bike parking?
Make sure you do regular maintenance (e.g. cleaning and lubing) more often if it's going to sit out in the rain.
For a temporary fix, how about a big garbage bag and rubber bands or bungees to hold it on?
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Countries I've ridden in: US, Canada, Ireland, UK, Germany, Netherlands, France, China, Singapore, Malaysia
States I've ridden in: Illinois, Connecticut, Massachusetts, Pennsylvania, California, Nevada, Missouri, Colorado