@tbtb thanks for the link. I've ordered one.
My blackburn mars 4.0 has just packed up after about 18 months service. Blackburn claim to have a lifetime guarantee so I emailed them who asked me to email Madison. Who fobbed me off and asked me to take it to the store i bought it from.
I've lost my proof of purchase but fair play to Joe at
Evans Cycles in Clapham, he took it back and said he'll post it to Madison and lets see what happens.
TBH, if Blackburn offer a lifetime guarentee then I should get it back but I don't hold out a lot of hope tbh. I'll let you know.
IF if get the blackburn replaced then it'll work with the Smart, if not then my Cateye LD600 won't be quite going into retirement yet.