That’s up to you, there’s no reason you can’t but they will almost certainly increase noise and reduce your fuel economy. We spent some time testing to see if we noticed a big difference in the noise with a rack mounted and while we didn't, every situation is different. If you do plan to leave the system installed all the time, the fork mount systems tend to be a bit smaller and more aerodynamic with fewer pieces that could possibly move around while driving. On the other hand, if you plan to regularly remove your rack Yakima, has the fastest and easiest system for attaching the rack to the base bars. While there are no major reasons not to leave a rack attached to the car, you will want to think about your plan as part of the buying decision.