Looking for ideas to mount gears to wheels

Need some help,
I am in the progress of building a robot which will use 2 lawn mower wheels on a single shaft. I am using this method due to the final weight of the
robot (~100 lbs) and the fact that I was concerned with radial torque I would have if I tried to drive the wheels directly with a coupler or such.
Each wheel is to be driven separately by their own drive motors. I am thinking of using a large metal gear, maybe from a bicycle, and chain driven, but have not been able to figure a way to mount the gear to the wheel. Any help is greatly appreciated. Also looking for sources for large metal gears say 4-5" in diameter.
Daryl
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Use a key and keyway, which is what everybody does in industrial machinery. Find out what a Woodruff key is. You can machine a keyway into the shaft with an appropriately sized grinding wheel on a Dremel tool. Although it's far easier with a milling machine.
                John Nagle
daryl wilde wrote:

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Thanks for the info but this is not my issue. I need to faster the gear to the wheel - not the shaft. The gear and wheel when fastened together will turn freely on the shaft on till hooked to the drive belt.
Thanks Again Daryl

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Front drive gears on a bicycle typically have a 5-bolt pattern where they bolt on to the 'spider' of the crank.. You could easily find a pair of small ones that you could bolt directly to the wheels with maybe a couple of washers to make room for the chain. Cruise around your local bike-shops and look for a junk box. Lots of bits get tossed that aren't up to the demands of 200lb trunk-thighed cyclists that'll work just fine for your bot.

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