Despite what you my read or hear there is only one size chain
that
fits the original Bantam sprockets
namely Renold 110044 0.5mm x 5.2mm x 8.51mm
it seems many online retailers are selling 420 chain as an
equivalent even those supposedly Bantam specialists.
As you can see from the chart below 420 chain has
a roller size of 7.75 which is almost a millimeter smaller then
the Renold and will destroy your sprockets in no time at all.
1/2"x 3/16 (415) is even worse as it is narrower
with the same size rollers as the 420
one Large retailer says this on their website
"BSA/Triumph Bantam/Cub
and similar earlier lightweight British motorcycles need a Original
chain. This is because metric equivalents, although having the same
pitch has different size rollers which will not correctly seat into the
sprockets and will very quickly knock the tops off the sprocket teeth.!
and then goes on to list four 420 and 1/2"x 3/16 (415)
chains for a Bantam, unbelievable,
so be careful what you buy.
A Regina 125EBSR chain is also the correct size and
a direct replacement for the Renold and is sold by
http://www.the-chain-man.co.uk/ and http://www.tradeclassicbikes.co.uk/
you can also buy 420 sprockets
to fit the Bantam and this is probably the way to go if you intend to
keep the bike and use it as the Renold chain is
becoming increasingly scarce and is now 4 times the price of a cheap
420 chain
T&G motorcycles stock the 420 sprockets £9.50 front £21.75 rear
(09/2012 price,
Original Bantam Sprocket sizes
D1/D3 Rigid = 15 & 47 - 116 Pitches,
Competition 58 - 122 Pitches(125 cc - 19" Wheel)
D1/D3 Plunger = 15 & 47 - 117 Pitches,
Competition 58 - 123 Pitches (150cc - 19" Wheel)
D3 Swinging Arm = 15 & 47 - 121 Pitches (150cc - 19" Wheel)
D5 = 16 & 46 - 121 Pitches (175cc - 18" Wheel)
D7 = 16 & 47 - 120 Pitches (175cc - 18" Wheel)
D10 = 16 & 47 - 120 Pitches (175cc - 18" Wheels)
D10 Bushman 47 or 58 - 122 or 128 Pitches (19" Wheel)
D14 = 16 & 47 - 120 Pitches (175cc - 18" Wheels)
D14Bushman 47 or 58 - 120/2? or 126/8? Pitches (19" Wheel)
B175 = 16 & 47 - 120 Pitches (175cc - 18" Wheels)
B175 Bushman 58 - 128 Pitches (18" Rear Wheel)
420 Chain on top you can actuality SEE the difference in size
