Re: [CR]Worn cotter pins?

Going back to basics: first the terminology: The pedal is the rotating thin g that you put your foot on.  The pedals are screwed into the ends of arms called cranks which, in your case are secured to the bottom bracket ax le (more terminology) with cotters.

If things are waggling about, there are a number of possible causes:

The pedal bearings may be loose - in which case, the pedal will waggle with the crank held still. The pedal may be loose in the crank - symptom as above. One or both cotters may not be holding the crank securely - in which case o ne or both cranks will ROTATE slightly on the bottom bracket axle - this is likely in your case if you hold one crank and the other crank will rotate slightly backwards and forwards. The bottom bracket bearings are loose (or completely shot) - in which case the bottom bracket axle will waggle in every direction - you can check for this by waggling the cranks IN and OUT (as opposed to trying to rotate them ) and watch to see if the axle waggles and feel for any significane free pl ay. As a final check, I would remove the chain and see if the cranks rotate smo othly and quietly.  If not you need to check the bottom bracket adjust ment and, if that is not the problem, service the BB.  You can keep go ing quite a while if your bottom bracket has pitted bearing surfaces, provi ded it is clean and adjusted right, but it can be problematic if the balls are breaking up or there is contamination of the bearings, which is why I s uggest this check.  If you have this sort of BB trouble, the only sens ible thing is to overhaul it, which is not too difficult or time-consuming if you have the right tools, but is a total pain in the rear if you don't.  
>From your description, it sounds like the cotter pins are the problem, in w hich case Marten's suggestion will fix it.  However, I would suggest d oing the other checks to make sure it is not something else or in case more than one thing is wrong.   

Hugh Thornton
Cheshire, England