Mystery knocking

Baxter22
Posts: 14
Joined: Wed Jan 09, 2013 1:55 pm

Mystery knocking

Postby Baxter22 » Wed May 20, 2015 9:12 am

G'day,

I recently put a new rear wheel on my singlespeed. Had the local bike shop near my office do the work after I blew apart half a dozen spokes on my morning commute. I rode it for about a week and I then started to notice a knocking coming from "somewhere" in the drive train when I put a decent amount of force through the pedals, specifically at the bottom of the pedal stroke. Normal pedalling (not under considerable force) I dont hear the knocking.

I have checked the chainline, all the nuts, hub on the new wheel and the bottom bracket for any cracks there but still no luck. Its a bit hard to identify where its coming from whilst riding. The next step is to pull the whole drivetrain off for an overhaul but its not that old.

Anyone have any ideas what it could be?

Cheers for any help

rustychisel
Posts: 3489
Joined: Thu Jan 10, 2008 1:39 pm

Re: Mystery knocking

Postby rustychisel » Wed May 20, 2015 2:03 pm

notch or bent tooth of rear cog, or possibly chainring? Also, check your chain carefully for unseated pin, slightly bent link, or any shiny bright spots indicating unusual wear pattern.

Before you do that, however, try to isolate the knock by riding the bike and working out whether the noise is once per wheel revolution, once per crank revolution, or once per chain revolution. That'll help you work out what you're dealing with.

User avatar
HLC
Posts: 720
Joined: Sun Mar 04, 2012 11:23 pm
Location: Sydney.

Re: Mystery knocking

Postby HLC » Fri May 22, 2015 7:41 pm

Chainring bolts.

Baxter22
Posts: 14
Joined: Wed Jan 09, 2013 1:55 pm

Re: Mystery knocking

Postby Baxter22 » Thu May 28, 2015 9:14 am

After a couple more rides, help from a mate riding along side to listen in and a very close bike inspection, turns out the creaking wasnt coming from components. Flipping the bike turned up a hairline crack in the frame just behind the bottom bracket on the right hand side. A quick ride after the inspection made it worse and the rear end got splashy. Cheap frame that lasted a year so cant complain. Positive is that a new bike is on order.

Cheers for the help.

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Gordonhooker
Posts: 417
Joined: Mon May 06, 2013 9:11 pm
Location: Brisbane South Side

Re: Mystery knocking

Postby Gordonhooker » Wed Jun 03, 2015 12:56 pm

Thank God it didn't break when you were out riding in traffic.... a new bike is in order.... I like that idea... :D
OI onya bike!!!

eraser215
Posts: 53
Joined: Tue Aug 13, 2013 11:41 am

Re: Mystery knocking

Postby eraser215 » Wed Jun 03, 2015 11:26 pm

Wow, very lucky! I am glad you were able to find the problem before a catastrophic failure and all that could entail...

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