Crank arm has come off

Does anyone know how to re-fit a left crank arm on a wisper 905 se sport.

It came off whilst I was cycling home and although I tried to push it back on, there doesn't appear to be anything to fix it too.

Any help would be much appreciated.

moon

There is a nut that holds it in place that fits inside the crank, if you have lost that then you'll have to get another. If you have it then a bit of threadlock may stop it all falling off again but you'll probably need a new crank arm as the taper will be damaged.

It's easy to get the wrong part so unless you fancy replacing the whole crankset then you should speak to Norman at Wisper, that's how I got mine fixed.

You'll find my threads about it in here somewhere.

Thanks Mussels, I've contacted Norman and I'll do a search for your thread.

All sorted now, I got one of these socket spanners and tightened the nut, Norman sent some new ones but I realised the nut was still inside the crank arm

http://www.ajbikes.co.uk/images/products/thumbs/AJ60950604.JPG

All sorted now, I got one of these socket spanners and tightened the nut, Norman sent some new ones but I realised the nut was still inside the crank arm

 

http://www.ajbikes.co.uk/images/products/thumbs/AJ60950604.JPG

I tried that but it may well work loose again soon because the taper is damaged, I also found that tool didn't have enough leverage to do it up tight enough. Threadlock is a good thing to stop it falling off in the short term.

I tried that but it may well work loose again soon because the taper is damaged, I also found that tool didn't have enough leverage to do it up tight enough. Threadlock is a good thing to stop it falling off in the short term.

Make sure you grease the spindle (the square bit) before you put it on. Sounds backwards I know, but it helps the crank go on, and prevents it chemically welding itself onto the spindle. If you don't do this and need to remove the crank at a later date e.g. to service the bottom bracket, you might end up having to cut it off. (I know this from personal experience!) So grease up the spindle. ( The same applies to pedals too)

On the slightly OT, err, T of removing cranks, I have a fantastic tool - a Crank Extractor!

http://www.onyourbike.co.uk/images/medium/tlfc10.jpg

On the slightly OT, err, T of removing cranks, I have a fantastic tool - a Crank Extractor!

 

http://www.onyourbike.co.uk/images/medium/tlfc10.jpg

So do I! I also have a spanner, and 14stone of body weight.... that b***er wasn't shifting, it started to strip the threads on the crank! I even rode around for 2 weeks with the nut missing. It didn't budge a nanometer.

Heating the crank with a gas flame, didn't help either. Neither did soaking in ammonia.

Eventually (thanks to Mussels) I removed it by using a Dremel and a hack saw to cut a slot in the crank. A swift bang on a screwdriver inserted in the slot and the crank fell off.

On examining it closely the actual amount of "weld" was practically invisible, but it was able to hold the crank on despite all that force & other "encouragement".

Aluminium + Steel + Water = Electrolytic Chemical Weld.....it's a well known problem encountered anywhere where alloy & steel meet. In particular cranks + BBs, pedals+cranks and seat post + frame. Grease the parts before assembly if you ever want to separate them in the future.