A short distance away from Bukkittinggi in West Sumatra there’s a lovely volcano lake called Lake Maninjai in which you could bicycles and ride around this lake (70kms). Here is the number of a place with accommodation – no doubt they may be able to help you organize bicycle hire. (or you could just do it via a car if you are not the sporting type.)
Pasir Panjang Permai
tel (0752) 611111
fax (0752) 61255
There are a few accommodation places around the lake also or you can just sit in a lakeside view restaurant for lunch or a drink.