Help on finding/building a new road bike on a low budget
Hi I'm about 5'3 or 160 cm. My leg length is 76 cm. My frame size is 52cm. My crank size is 170mm. I am either buying a new bike for casual riding or to think about life sponsored by parents. My budget is $300 tops. Im 13 so I don't need top end stuff. I can add more to budget if I love riding bike which will provide to brakes, wheels etc. I can also build a road bike but please list all items so I can research on. I am looking for a road bike. I'm ok if it is used just not from craigslist or anything. I was looking at a gmc denali road bike for it fits my size. I know it has bad wheels and brakes so if you can list some ok gear for me it will make my day.
If you are going to hate please get off my thread because I'm really interested in people's real ideas. Please also tell me a road computer to track my mph and how far I'm going. Will really love a thumb shifter. If it is necessarily I can also ride a single speed bike like a fixie but I don't want people at my public school to judge me and how I bought the bike just to look cool. I love riding bikes and want to have fun while going at top speeds. Thank you for all your thoughts and ideas.
Edit: There ain't that much hills in my area.