following on from above...
451 is a larger narrow rim- skinnier tire combination in the nominal 20" wheel category ..
then you need a different brake because the rim is larger diameter..
406 to 451 is a radial difference of 22.5mm ....
In the past someone found an adapter for Direct pull brakes , V type.. frame pivots..
some one had made, for the purpose.. Online link.. picture, offered..
...
Last edited by fietsbob; 06-11-19 at 11:34 AM.