I honestly recommending just getting a MTS trolley pass and using it to get around San Diego during Comic-Con instead. MTS hasn't updated their Comic-Con trolley info page yet, but here it is for reference: You are not allowed to view links.
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LoginThey'll likely update it in a few months.
Although if you really would like to try biking to the convention center as an option... (San Diego is rather nice outside in July, even if it's a bit warm during the day at times.)
As for storing your bike, there are some bicycle lockers located at the Gaslamp Transit Center. You can take a look at the location on the map on the web page I provided in the other post (here's a link for convenience: You are not allowed to view links.
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Login). If you zoom in to E. Harbor Drive, where the convention center is located, you can see a diamond with a bike logo on it--that's a transit center.