John, I am 68 also and have a 29" mt bike with 1000w DD rear I have a Cali 48 volt / 20 AH battery and Lyne Controller and a Cycle Annalist. 3 years old and have now road 5,000 miles. A few normal parts chains and sprockets are the only replacements. At 25 mph I can get 20-25 miles (new) after...