Crank slipping

My cranks keep slipping under pressure and I am not really sure why. Both Crank and BB are new and seemed to be a snug fit when I installed them. Does anyone have any suggestions or am i just going to have to fork out for a new set?

http://www.sheldonbrown.com/brandt/installing-cranks.html

good luck

Are you sure it's the cranks? Slipping?

The only time I've had that sensation it was my sprocket not being on tight enough and my lock ring being just a little loose. The rear cog would slip a little, and that meant that the pedals felt like they were slipping. If this sounds similar to what you're experiencing, check the cog and lockring and not the cranks.

If the crank is slipping around a square taper BB or splined BB you are fscked. Replacement time.
If it's something else in the driveline you can fix it.. maybe loose sprocket, loose lockring - does it slip after you've applied backward pressure? Oh, is it fixed or ss? DETAILS PEOPLE! It could be your freehub pawls not engaging but we don't know because you forgot fixed, ss, geared.. etc.
(don't mind me.. late night, early morning)

I don't want to hijack this thread, but is it possible for a spider to become detached from the crank?

I have some '70's vintage SR cranks which seem to have developed a 'click-click-click' as I apply pressure to the pedals. It is the same sound in going forward or in braking, and always just three clicks as the pressure is increased. Once the initial pressure has been applied in that direction, no amount of stamping on the pedals causes any more clicking, even if the chain is tight or slack.

It's not the chain, sprocket, lockring, pedals or cleats. There is no crack in the frame.
BB is tight, square tapers are good condition and uber tight.

What's going on?

Chain ring bolts? Tight enough?

Chainring bolts are solid.
If I put weight on the pedals while the bike is stationary and feel the cranks/chainring/spider, it feels like the clicking is coming from the right crank. There is no slippage between the spider and chainring.

It is possible but not exactly common..

How do you know "It's not the chain, sprocket, lockring, pedals or cleats. There is no crack in the frame."

It's probably your saddle rails or seat post. Remove both, clean, insert, tighen.

Chainring bolts are solid.
If I put weight on the pedals while the bike is stationary and feel the cranks/chainring/spider, it feels like the clicking is coming from the right crank. There is no slippage between the spider and chainring.

If I put my weight on you, you'd probably make some odd noises too :)

Take it all apart, grease where appropriate, put it all back together. :)

Could be cleats - if you're using them obviously

"It's making a noise" but then you eliminate every part on your bike that could be causing it hahaha

"It's making a noise" but then you eliminate every part on your bike that could be causing it hahaha

Errm, that was my thought too.
I've checked (and reassembled) all I can but still no difference, which is why I asked the question. Can right crank arm come loose from spider?

Stumped :(

isnt the crank arm cast/moulded well 'part of' the spider

ie, they are one solid lump of metal ?
or is that just newer ones ?

Errm, that was my thought too.
I've checked (and reassembled) all I can but still no difference, which is why I asked the question. Can right crank arm come loose from spider?

Stumped :(

what style cranks are they? if they're one piece forged crank and spider if the 2 aren't one piece you're probably fscked already. check for cracks.

the only possibility of them not getting along are those cheapo cranks with forged crank and a tin foil chainring/spider attached.

I figured out that the chain-ring bolts are coming lose? No matter how much I tighten them they become lose by the time I finish my commute (about 8 miles). Should I replace or is this a common occurance?

clean both threads, and use threadlock.

what he said^

Its a glue stuff by the way, ask at your hardware shop. You need to let it dry overnight.

clean both threads, and use threadlock.

NO, used a chainring peg spanner and they don't come out ;)

what's a peg spanner Dale?

one of these