Originally Posted by
pibach
New fork is 3cm lower, i.e., ~1,5 cm lower BB. 451mm instead of 406 wheels compensate to rize BB by 45mm, thus it should be 3cm higher (!) not lower. Slim Durano tires again get it lower.
If you mount 406 rims and 451 rims on your bike, both without tires, you would lower the bike by 22.5mm, not 45mm. "Normal" 451 tires will have a lower profile than "normal" 406 tires. The difference in effective rolling diameter is smaller than you think.