Bottom bracket bolt missing?

[geopat]

Whilst cleaning and drying of my bike after a particularly damp ride today I noticed a hole on the left side of the bottom bracket? - sorry not sure of the terminology. Looks like I've lost a bolt as there are just lots of bare threads. Can't believe with the amount of threads on it it has came off the bike within 1 year. The missing bolt didn't seem to affect the performance of the bike on the road. Drivetrain is Tiagra 2011.

Can someone point out what I've lost so I can replace it. Thanks.

 

[accountantpete]

You have lost the Fixing Bolt.

It's a little plastic bolt that preloads the bearings. You should be ok without it as the two bolts in the crank hold the arm firmly (the bolt is just used in installation).

https://www.google.co.uk/search?q=F...44,d.d2k&fp=4c83898c44ba3aa7&biw=1280&bih=866

 

[mickle]

Pictures.

 

[geopat]

You have lost the Fixing Bolt.

It's a little plastic bolt that preloads the bearings. You should be ok without it as the two bolts in the crank hold the arm firmly (the bolt is just used in installation).

View attachment 19604

https://www.google.co.uk/search?q=Fixing Bolt&aq=f&oq=Fixing Bolt&aqs=chrome.0.57&sourceid=chrome&ie=UTF-8#q=hollowtech fixing bolt&hl=en&source=univ&tbm=shop&tbo=u&sa=X&ei=DY8qUYC9DqiZ0QXqoYCYCg&ved=0CFUQrQQ&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.42768644,d.d2k&fp=4c83898c44ba3aa7&biw=1280&bih=866

Thanks, do I need a special tool to replace the bolt?

 

[djb1971]

You can get a special tool but it isn't needed. You can either use something that wedges into the slots and turn it or use your finger!

The bolt should only be torqued to something like 1-3nm so I wedge my index finger into it and turn as much as it'll go, this preloads the bearings without over tightening. Make sure you undo the 2 crank arm bolts before fitting this, fit this bolt then fasten the two bolts on the arm again.

 

[geopat]

You can get a special tool but it isn't needed. You can either use something that wedges into the slots and turn it or use your finger!

The bolt should only be torqued to something like 1-3nm so I wedge my index finger into it and turn as much as it'll go, this preloads the bearings without over tightening. Make sure you undo the 2 crank arm bolts before fitting this, fit this bolt then fasten the two bolts on the arm again.

Do the crank arm bolts only require a standard Allen key to loosen?

Thanks again.

 

[accountantpete]

Do the crank arm bolts only require a standard Allen key to loosen?

Thanks again.

Yes - they might be a bit hard to undo as the shop may have put some threadlock on to stop them undoing.

 

[geopat]

Well that didn't go well. My fault for being too lazy to check the size before ordering.

The above recommended replacement is way too big. Looks like I need a much narrower and longer bolt like this
http://www.treefortbikes.com/product/333222347360/263/Shimano-Hollowtech-II-Crank.html

I'll go to a bikeshop to get the correct part this time.