That is probably true, but all the others like Matchless etc etc seemed to manage ok with rollers and Ariel actually used crowded (and two row) short rollers in the two stroke twin Arrow!(dunno if that was a wise move)
I seem to remember that one of the British model aircraft engines used "floating" wedge like segments between the rollers in their crankshaft mains which were not connected to each other (can't remember which company - it'll come to me)... Taplin maybe.
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