PABLO: yes youre right they are not as good for the regular or "ultra" slim bicycle chains, because they are considered WAY too heavy to carry around with you on rides and tours. the little bicycle ones wich are similar to the ones on the previous page, are lighter and do the job just fine (for bicycles), and are manufactured from things like aluminium too. these however work fine for the shop, and since we arent pedaling carrying one is not a problem.
These are actually much, much easier to use than the standard bicycle chain breaker. when you say they are too big, you might have come across the larger ones that open chains in some automotive applications for example. that would be too big and more like $25.99. there are different sizes of chain breaker. there are some so small you CAN'T use them on a bicycle chain.
BIKEGUY JOE: its best to look in person to see the right size and to save some money on shipping. it makes no sense to pay $7 shipping for an item that costs between $5 and $15 that you can get at any automotive shop, or even sears for that matter. just pull over on your way from work or a shopping trip.
I would advise to get something decent, instead of going too cheap because a good one these things will last decades (mines used to be my grandfather's). it's a one time purchase. the ones in the 98cent store near my home sells for $4.99 and it looks like its ready to come appart. while for $10 you can get a good one that will last longer. Alternatively you can just get AMERICAN MADE and it will last as long as you. for more money you can get nice rubber on the handles if you have sensitive hands, although its so easy to turn I dont see why. Or you can spend $30+ at motorcycle shops and get them with cool "radical" colors too.
this is the size we need for these applications, NOTE: size #41 chain. a very good US made chain breaker
Roller Chain Breaker #25, 35, 41, 42, 50 & 60, USA Made - eBay (item 260234578188 end time May-03-08 21:35:51 PDT)
this is one thats too large cheap chinese breaker, I found the smaller version for$5
eBay Motors: Daido Chain Breaker #60 - #100 New in Package (item 120254296991 end time May-04-08 16:03:30 PDT)