Bottom Crank Issue
 

OK, so for the past few days my bottom Crank had started to squeak and has now developed a wobble where both arms move together. I currently have a SM-BB51 installed and as I use this bike for commutes to work... kinda concerned. Im great full for any and all help so thanks in advanced!

Look a PDF! si.shimano.com/php/download.php?file=pdf/um/SI-1L60A-003-ENG.pdf

you planning to buy more tools? replace the BB or the crankarms ... No? ... take it to a Bike shop.

Blind Guessing I cannot do..

... onward to 20 questions as others try to pry out details from you one at a time..



...

Being a commuter minimizing the down time is usually a high priority. This is when a pro with the right tools and the right replacement parts being at hand as well as their skill at doing the job quickly is a very good consideration. Every commuter who has to ask the kind of question the OP does really should establish a relationship with LBS if at all possible. Yesterday I did two different service jobs for the same woman. One of her way to work and the other as she left work. Both done on the spot (the first was a brake repair and rack replacement, the second was a tire replacement and middle chainring replacement that required drilling out all 5 ring bolts). She was so happy to not have to leave the bike for the night. Andy.

I'm with Andy - get it to a shop if possible. Waiting a "few days" is already too long.

Bearing cracked, and or spindle cracked. Failure is imminent.

If you're comfortable taking the crank out, you could probably inspect the spindle - if that's good you can probably wait for a convenient time to replace the bearing. If the spindle is cracked you don't have many revolutions left in it.

Cheers, this at least this give's me an idea in what could possibly wrong. Ill forward this information on when take it to the shop. They will obviously probably already know but still cheers again!

Once steel reaches the yield point and bends the next thing that happens is it will snap & break. You need to get the bike on a rack & take a good look at what's going on down there. Otherwise, next time you stand up on pedals to climb a hill or accelerate - the axle could snap in two & instantly dash you to the ground.

The bb is worn out. If you know how replace it or take it to a shop.