I've posted about this before with photos. Buy the MyTouch hard case that T-Mobile sells, a Timex handlebar mount, a velcro strap, and some industrial strength stick-on velcro pieces. Cut two slots in the back of the case, run the strap through, apply a piece of velcro to the back of the phone, then assemble phone in case. Apply velcro to the back of the case, then staple a piece to the rubber handlebar mount. Make sure the strap is long enough to wrap around stem and then fasten to the upper part of the case with a small piece of velcro.