John Surtees had one of these Seeley front brakes on the front of a Vincent. I have been wanting to find out how the brake shoes and adjustment were designed on this hub. A quick internet search reveals that Molnar offer them, a snip at £1850 + VAT..... I have seen replica Ceriani 230mm 4ls brakes offered for a very similar sum. Are the Seeley brakes really comparable?The most powerful drum brake of all time is the duo-servo brake.
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It was not a popular brake, but it is superior to double twin leading shoe brakes in performance. It is considered a single leading shoe brake by racing organizations. It is not very popular because it is wildly unstable, but if set up properly it will probably out-perform a big twin disc. This brake design was also used extensively in cars and hydraulically operated.
FWIW this arrangement of linked brake shoes can be found on bicycles for small children, usually Continental ones. They are very good for small hands without much strength.