Hill cycle - slight knock out of pedal

yop

Folks
Last 2 spins I noticed a knocking out of the pedal or the shaft which goes through the bike.

I tightened up both where the pedal arm connects to the bike and the pedal to the pedal arm but no dice.

About 2000 km on the bike.

Any ideas what I need to replace?

I have Gaelforce next weekend so concerned that there maybe an issue that could break down on the spin!

doozerie

Sounds like you are referring to the bottom bracket when you mention "shaft". The bottom bracket is the axle (plus bearings) that sits in the frame and to which the cranks attach. How to deal with it depends on the type of bottom bracket you have. Generally speaking, the older style ones are self-contained sealed units which are independent of the cranks - these ones tend only develop play if they come loose (which shouldn't really happen if fitted correctly from the outset) or if the bearings are very worn (in which case you'll need to replace it).

More commonly these days though the bottom bracket is no longer self-contained and the axle is actually attached to one or both cranks while the external bearings are separate. In this case it may just need adjusting to tighten things up or again the bearings might need replacing.

This Park Tool page is a good place to start to get some idea of what may be involved for your bike. You'll need a few tools to do any adjustments/replacements yourself, and the tools differ depending on the type of bottom bracket.

doozerie

Oh, and just in case you have an older square-taper type of bottom bracket: these can come loose, if not fitted/tightened correctly originally, and so you might have to tighten the cranks but because they are basically jammed onto the axle (the axle widens as it goes deeper into the crank) you have to be careful not to apply too much torque when tightening them up. The cranks are usually pretty robust but I've read of people applying so much pressure that the crank was pushed too far onto the axle with the effect that the opening in the crank was widened - this will lead to play between axle and crank and the crank had to be replaced. I think it would take an awful lot of torque to cause that kind of damage but it is something to be aware of.

yop

Ok, thanks for that. Its a Giant Defy 4, but I will look at what u suggested. Everything is definately tight so maybe its a bearing that is going.

Thanks

doozerie

Make sure you rule out some other things before focusing all of your energy on the bottom bracket though, as such issues can be very tricky to diagnose. A "knocking" noise apparently coming from the bottom bracket for example could be caused by a variety of things - from something as simple as the cranks hitting something like the front mech on each revolution, to a loose axle in one of the wheels, and a whole bunch of things in between.

If the bottom bracket really is loose then you should feel this by dropping off the chain, holding one crank in each hand, and trying to rock them to feel for play. While the chain is still off, spin the cranks slowly to feel for any roughness in the bearings (although the mass of the cranks themselves can often hide/smooth out shot bearings so the results of this test are by no means definitive).

yop

No rocking in the cranks at all, I tried that last night. Its an odd one for sure, I must check the axle as well now and see.

07Lapierre

yop wrote: »

No rocking in the cranks at all, I tried that last night. Its an odd one for sure, I must check the axle as well now and see.

Not odd at all, very common in fact. Check the headset. I had a similar problem a few weeks ago. i removed the front fork, greased up the bearings and refitted. Problem solved.

yop

Great job Lapierre I will try that tomorrow when I get back down to Mayo

rughdh

A slightly loose chanring is another thing to check for. You won't necessarily notice it until you are climbing.

SubLuminal

had a knocking coming through the pedals on my bike recently, thought it was the bottom bracket until I ripped the cassette off the freewheel going up a hill! Stripped the threads right out, was just a machining/factory error on the part I guess.

07Lapierre

So to sum up...knocking noise from BB. The LEAST likely cause is the BB itself. Noise can be caused by, Headset, Pedals, Chainrings, Cassette, and any other part of the bicycle you care to mention.

My money's still on the headset..:D

yop

07Lapierre wrote: »

So to sum up...knocking noise from BB. The LEAST likely cause is the BB itself. Noise can be caused by, Headset, Pedals, Chainrings, Cassette, and any other part of the bicycle you care to mention.

My money's still on the headset..:D

Yes you were spot on, I had a look at it this evening, and sure enough when I put pressure up and down its the headset, now I had no time on my hands so couldn't do a major job on it, and to be honest I don't know how either

So I just took the top nut out and sprayed some grease into it.


Now, could this cause me issues on the Gaelforce on Saturday? As in will it break or anything? Sorry for the stupid Q

Thanks

07Lapierre

yop wrote: »

Yes you were spot on, I had a look at it this evening, and sure enough when I put pressure up and down its the headset, now I had no time on my hands so couldn't do a major job on it, and to be honest I don't know how either

So I just took the top nut out and sprayed some grease into it.


Now, could this cause me issues on the Gaelforce on Saturday? As in will it break or anything? Sorry for the stupid Q

Thanks

Sprayed grease into it? is there such a thing as spray grease?(i've heard of spray oil, but grease?) Anyway. Really depends on the type of headset you have. Doubt if you've done any harm, but I also doubt if you've solved the problem either.

Also I doubt if its going to break as a craking headset in itself is simply annoying, but not really a problem unless left for a very, very long time.

If in doubt, bring it to you LBS and they'll check it for you. Cheers

yop

07Lapierre wrote: »

Sprayed grease into it? is there such a thing as spray grease?(i've heard of spray oil, but grease?) Anyway. Really depends on the type of headset you have. Doubt if you've done any harm, but I also doubt if you've solved the problem either.

Also I doubt if its going to break as a craking headset in itself is simply annoying, but not really a problem unless left for a very, very long time.

If in doubt, bring it to you LBS and they'll check it for you. Cheers

Aye, spray grease it is Dont know where I picked it up from, my Dad I think

Ya, I would say I did nothing to fix it really, I will do it when I get a chance now next week.

Canis Lupus

07Lapierre wrote: »

Sprayed grease into it? is there such a thing as spray grease?(i've heard of spray oil, but grease?) Anyway. Really depends on the type of headset you have. Doubt if you've done any harm, but I also doubt if you've solved the problem either.

Also I doubt if its going to break as a craking headset in itself is simply annoying, but not really a problem unless left for a very, very long time.

If in doubt, bring it to you LBS and they'll check it for you. Cheers

Lithium ion grease... In an aerosol can.