Hi Choy - and welcome to Bike Forums,

This topic has been VERY heavily discussed of late - and I'll (gently) advise you to check those threads. Crawdaddio's is still getting a lot of traffic - and there are several others.

Please look at those - and then let the Commuting Forum family know if there's something specific that we can share that isn't covered (ad nauseum) in those posts.

Once again, welcome