Fixing the Crank

When I updated the Raleigh Grand Prix with a  cotterless crank a few years ago, I didn't notice anything wrong,  but when I replaced the front derailleur recently I did notice that the sprockets are too far out from the frame. As this picture shows the inner sprocket is at least a centimetre out from the frame at the back, where it should be quite close, and the derailleur is at full stretch to get to the large sprocket. I know from looking recently that the spindle is a 5T with a 42mm length on the sprocket side.

Another thing that has bugged me is that when I had to replace the left hand crank I couldn't get a straight one like the old one was.

Then I looked up into the rafters and noticed that the Wasp ( yellow Peugeot with black mudguards) had a straight crank, so I thought that I would swap them.

When I took the crank off I noticed that the end cap seemed to be protruding more that I might have expected, leading me to believe that the spindle had too large a centre measurement to the shoulders. Note the picture (sorry that it is not a good focus)

So I removed the spindle and replaced it with one of the correct size. The one that I removed seems to be quite large in the central dimension. To understand this you need to consult www.sheldonbrown.com/bbsize . The markings on it are not common ones. I will expand on that when I have an explanation. It is possible that it will fit appropriately in the Grand Prix, though the ideal spindle is a 5N.  

11/9/14   Still cannot find an explanation of the markings, but it seems that the central dimension is 57mm, according to the LBS, therefore not appropriate to the bike. So I binned it.

Another test that I did today was to come on to the smaller sprocket and note that the shaft of the derailleur was still 9mm extended, so therefore in theory I could reduce the length of the spindle by 9mm from the current 42mm.


4 Feb 2015

This 5T spindle  was not symmetrical. I have been shopping around for the 'ideal' spindle as noted above, and yesterday after visiting the Forge Cycle Works in Ringwood and asking if they had a spindle to fit, I came home and swapped the spindle around so that the long end is on the left side. This has made the changer fit nicely and work well, and then I decided to measure the distance from the seat post out to the end of the crank. On both sides this was 6 cm which means that the crank is now, as far as I am concerned, symmetric. Also each crank  missed teh frame by about 1.5 cm at it's rearmost position.

Too me this is perfect and I am a happy guy.