If you were racing one competitevley i would say 10 stone would be the limit, i trackdayed one a few times last year, and being 13.5 stone wasn't realy a problem, it was more the physical size of me and the bike that made it damm hard work, iam about 5ft10 -5ft11 and it was hard work trying to squeeze on, having said that iam getting on a bit and a bit stiff, so if you are young and supple, might not be a problem. you can get longer footrests hangers to help a bit, it also helps if you get one with a low first gear fitted. You realy need to sit one first that will give you an idea. Cheers Les.
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Proud Father of , 05 ktm 400exc supermoto 2018 honda crf rx supermoto