In principle, if you buy a bike for business (eg if you're a cycle courier) rather than to travel to work then this is a business cost.
There are various ways to claim this cost. You can choose which to use:
- If it's exclusively for business, then you can put the bike as a business expense ... including it as an expense in the Self-Employment tab in untied lite, or just by tagging it in untied Pro.
- If it's a mix, then you can apportion the business element of your bike costs (including equipment and maintenance costs) ... again this would be in the Self-Employment tab in untied lite, or using the splitting functionality in untied Pro (see the linked article)
- You can claim a fixed rate per mile. In the Self-Employed Mileage tab in untied lite, just enter the number of miles and untied will calculate the right rate. Or use untied Pro's automatic journey logging function, or add a total at the end of the year