Chainset pedal problem...

[Grouchfungus]

Disaster of a ride tonight.

I'm a newbie so please bear with me here....not sure of the correct tech names for all the bike bitz.

Got halfway round the ride. Chainset/pedal assembly fell off. The securing bolt had sheared off. Limped home for 4 miles having to tap the chainset/pedal assembly back onto the spindle every couple of revolutions.

Will it be possible to get the broken thread out?? And replace with a new hex bolt? The chainset was recently repaired by the LBS as the largest cog was bent.

The bike's a Specialized Hardrock BTW ....

 

[fossyant]

Have some strong words with the LBS.

You'll have to have a new BB if it's a square taper or isis (square BB axel or a serrated one) - that's not a problem as the drive side is off. The shop/or you can undo the non-drive crank arm, isnser removal rool, undo lock ring, go to drive side and remove whole BB.

Not worth trying to drill out the snapped bolt.....I'd suggest big spanner monkeys at work.......

 

[jayce]

It should be fine i take its a square taper if so the bolt should come out ,if not might have too replace the bb

 

[Grouchfungus]

Have some strong words with the LBS.

You'll have to have a new BB if it's a square taper or isis (square BB axel or a serrated one) - that's not a problem as the drive side is off. The shop/or you can undo the non-drive crank arm, isnser removal rool, undo lock ring, go to drive side and remove whole BB.

Not worth trying to drill out the snapped bolt.....I'd suggest big spanner monkeys at work.......

Possible LBS overtightened? Or jus' bad luck? Common problem?

 

[Grouchfungus]

BTW what's a BB?

 

[PatrickPending]

bottom bracket

http://sheldonbrown.com/gloss_bo-z.html#bottom

 

[Grouchfungus]

bottom bracket

Duh! Should have been able to work that one out.

Thanks

 

[Tynan]

stright to the LBS with a hard stare, insist on all new FOC

bravo for getting home

 

[gbb]

When you say the chainset was replaced by the LBS Grouch...do you mean the whole crankset (cranks and chainrings)..or did they replace just the chainrings (the sprockets on the front)

It could be important, because if they just replaced the chainrings...they may not have even touched the bolt that goes into the axle.

It is possible (i'm assuming here) that when you bent your chainrings (i'm still assuming)...that you may have sprained the bolt, and it was just waiting to break. You (and the LBS) wouldnt neccessarily have realised.

Just a theory

 

[Grouchfungus]

When you say the chainset was replaced by the LBS Grouch...do you mean the whole crankset (cranks and chainrings)..or did they replace just the chainrings (the sprockets on the front)

It could be important, because if they just replaced the chainrings...they may not have even touched the bolt that goes into the axle.

It is possible (i'm assuming here) that when you bent your chainrings (i'm still assuming)...that you may have sprained the bolt, and it was just waiting to break. You (and the LBS) wouldnt neccessarily have realised.

Just a theory

The largest chainring needed straightening as it kept brushing the gear changing thingy. So the LBS guy was going to rectify. Probably adding 2+2 and getting five Just bad luck then.

 

[Grouchfungus]

The largest chainring needed straightening as it kept brushing the gear changing thingy. So the LBS guy was going to rectify. Probably adding 2+2 and getting five Just bad luck then.

I think he gave it whack with a tool known as a knockometer.

 

[gbb]

How did you bend the chainring in the first place Grouch...if it took a bang, thats when the bolt may have been damaged.
Hitting the bent chainring with a hammer seems acceptable to me (i've done it myself successfully)...but may have aggravated the already (potentially)damaged bolt.

If that was the sequence of events, i dont think i'd blame the LBS.

 

[Grouchfungus]

How did you bend the chainring in the first place Grouch...if it took a bang, thats when the bolt may have been damaged.
Hitting the bent chainring with a hammer seems acceptable to me (i've done it myself successfully)...but may have aggravated the already (potentially)damaged bolt.

If that was the sequence of events, i dont think i'd blame the LBS.

I bought the bike 2nd hand from a member of this site. It was like it already. Didn't notice when I collected bike.

 

[Gerry Attrick]

Just a thought, but if the chainring was catching the outer part of the front mech, did the LBS just (over)tighten the crank bolt to draw it further onto the BB?

 

[Grouchfungus]

Just a thought, but if the chainring was catching the outer part of the front mech, did the LBS just (over)tighten the crank bolt to draw it further onto the BB?

Not sure.

If you spun the pedals backwds you could see the large chainring wavering in and out. now it's not so noticeable so I think the slapometer came into play.