If someone is a professional cyclist - earning money on their bikes, whether through sponsorship, prizes, courier fees, or other methods - they can already deduct their equipment purchases. The only limitation is that they can't deduct more than their taxable cycling earnings. (In theory, they shouldn't be able to claim a bike solely for commuting, but the claim could be made that commuting is part of their training regimine, thus making it tax deductible.)

Many other self-employed people - including all those contractors you find in almost every IT department - are eligible for deducting their commuting expenses, so long as their home is their official place of business, and wherever they work is just a job site.