Translation:She needs to buy a new bicycle.
Yeah 铁马 would take some deciphering for Mandarin speakers... Another term for bicycle is 单车/單車. I thought it originated in Taiwan, but I don't know if it's still used there (EDIT: Looks like it is according to @FuCnSW 's comment below). It gains popularity in mainland China thanks to the bikeshare services/apps, which are called 共享单车 instead of 共享自行车, apparently because the former is more concise and perhaps more stylish.
For the record, "She's going to buy a new bicycle" is accepted.