I agree that weight loss will help in climbing. But a balance should be found between losing the extra fat and retaining as much muscle mass as possible. A quick reduction in weight will have your metabolism feeding on muscle (especially if you are very active on the bike). A proper diet that slowly reduces calories will be more beneficial. I would say set a goal on losing 1 to 2 pounds a week. This way your body isn’t shocked into thinking that it needs to drastically adjust your metabolic rate. To do this you need to burn - I think - 3500 more calories than you consume. Somethin like that. But this is all relative to weight, age, activity levels, calorie consumption, etc.

edit: Plus it's "lose" not "loose." I just had to throw that in.