SAN FRANCISCO (CBS SF) – The late Robin Williams was not only a comedic genius, he apparently was also a collector of unique bicycles.

Williams owned nearly 100 bikes and 87 of them are now gone up for auction with the proceeds going to two of his favorite charities — Challenged Athletes Foundation and Christopher & Dana Reeve Foundation.

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On the auction site the Williams family has posted a note saying: “We hope these bikes will bring their new owners much joy as riding them, as helping these causes always brought to him.”

The bikes range from a $5,600 cycle made by famed Italian framemaker and Williams friend Dario Pegoretti — there are currently 18 bids for the rare bike — to a $950 Schwinn unicycle.

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Among the most popular items so far is a Schwinn Chopper Hog Roadster priced at $2,000 that has 31 bids, a motorized Derringer priced at $3,841 that has 21 bids and a Velotron Training Bike with a pricetag of $1,6000 that has 22 bids.

Williams love affair with professional bicycling racing is also present in the collection which is housed at a San Francisco warehouse.

There’s a Pinarello similar to the bikes used by pro racing juggernaut Team Sky and a Trek Madone from the days Lance Armstrong rode with the Discovery Team.

The Williams auction runs through October 25.

Auction site Paddle8 co-founder Alexander Gilkes told the Wall Street Journal the collection was “near and dear” to his heart.

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“You’re buying into an extraordinary comedy and Hollywood legacy, and supporting two great causes,” he told the paper.