Mr Arbuckle (he's the 90 y o repair man in Noblesville) recommends putting a big fly wheel on any that you are going to treadle. He says they will move better. I'm wondering if that isn't why your 319s and your 328s give you such a work out. The 401g is very hard to treadle. He says he can do something to it to get a bigger fly wheel on it. He won't say how it would be done. I've been wondering what he would charge - he is a bit pricy - yet I'm thinking it might be worth it.