I have a 58t spur the 24t pinion might reach ..lol ....Its 28 degrees and icy here this morn to I will have to wait for bit......I may go to 5s right now I am using (2) 8000mah 7.4 maxamp lipos in series.....maybe use two 5s 5000 18.5v packs....I already have two 3s 5000 11.1v packs I could run in series...6s too much you think for 1515/1y?