Help needed with 'clonking' noise when pedalling

Stevo_666

As per the title, headed home on Friday night the bike developed an odd clonking noise when pushing down on the pedals with any sort of force - particlarly when standing up to go uphill. The noise sounded like it was coming from the crank area but could not be 100% sure about this while riding. It didn't seem to be gear dependent, more on the amount of force used to push the pedal and the (lack of) smoothness - seemed to be much less pronounced when deliberately trying to pedal smoothly in circles.

Also, oddly the noise was nearly only when pushing the right pedal :?: Had the bike upside down and nothing seems loose or visibly wrong. I couldn't replicate the problem by just pushing the pedals with my hands in the garage - which makes diagnoisis tricky.

The bike is the Boardman in my sig and is only 2 months old. I am using flat pedals & trainers so it's definitely not SPD related.

Any ideas folks?

Cheers,
Steve.

cjcp

Steve - any "play" in the BB or cranks which might suggest that they're loose? What if you change the pedals from the Giant onto the Boardman to see if that rules out the pedal problem?

Do you have the tools to take the BB apart?

If you're not sure if it's coming from the crank area, have you tried doing a few revs of the crank to see if the chain is jumping a little on the rear mech jockey wheels e.g. maybe a slightly bent link?

Might it be the chain catching on the front mech? (Although that's more a "scraping" sound.)

Stevo_666

Thanks CJ, I think I've already ruled out a few of these but it's still a bit of a mystery:

cjcp wrote:

Steve - any "play" in the BB or cranks which might suggest that they're loose? What if you change the pedals from the Giant onto the Boardman to see if that rules out the pedal problem?

No, they seem nice and tight. The pedals are pretty new and seem do be fitted properly with no obvious 'play' but may have a crack at swapping them tonight if time. Luckily the pedals are identical on both bikes.

cjcp wrote:

Do you have the tools to take the BB apart?

I have neither the tools nor the knowledge/skill, unfortunately

cjcp wrote:

If you're not sure if it's coming from the crank area, have you tried doing a few revs of the crank to see if the chain is jumping a little on the rear mech jockey wheels e.g. maybe a slightly bent link?

Yep, tried spinning the crank with the bike upended: the links all seem fine and seem to be moving OK through the jockey wheels.

cjcp wrote:

Might it be the chain catching on the front mech? (Although that's more a "scraping" sound.)

I've come across the chain scraping before on the Giant - it's definitely not that.

I'll have another try tonight and if I still get no joy, will take a chance on riding into town without anything breaking and drop it off at the LBS near my office.

Many thanks for the advice

Steve.

Stevo_666

All I can work out from more fiddling in the garage is that when pushing down on the right pedal, it feels like something in the BB 'gives' and the pedal moves down a couple of mm then stops, like it has slipped one tooth on cog. Only happens once per rotation. This has me stumped !

cjcp

The crank would move down first then. Cranks can work themselves loose if not tightened properly (I know from experience :oops: ), but you said they're tight.

Did the shop from which you bought the bike offer a free service after around six weeks? If the bike is only two months old, you could be entitled to this. But, if you haven't got the tools, take it in anyway.

Stevo_666

Well I should have said I thought they were tight :oops: but maybe not after that little test. Unfortunately no free service and in any event Boardmans are only available from Halfords: after my experience with buying it and the (rather basic) problems my LBS found with the way it was put together, I wouldn't trust Halfords with it TBH :evil: But that's another story...

Luckily I have a decent Cycle Surgery 5 minutes from the office so will drop it off there on Tuesday. With any luck they can fix it before I need to ride home again.

Cheers,
Steve.

cjcp

It shouldn't take too long to check/fix/tighten at all.

Mountainboy2465

Sounds like a bearing has gone on the BB.

N0bodyOfTheGoat

Reminds me of when the non-driveside square taper crank worked itself loose and then rounded the square.

Thankfully, my old boss runs a cycle project for local kids and supplied me with a new crank for a few quid!

Stevo_666

Just got the bike back from my LBS. It was a mixture of two things - the BB needed tightening and also the bolts that attach the cranks to the (axle? i.e thing that connects the cranks together) were loose. To be fair to Halfords they reckoned this was a factory problem.

Anyway, problem solved now.

Thanks for the advice lads 8)

Cheers,
Steve.

cjcp

Cool. Which chainset do you have, Steve?

Stevo_666

Hi CJ, its the Truvativ Touro compact 50x36T.

Got home without any gremlins in a record 54 minutes so feeling rather pleased with myself

cjcp

My RaceFace Cadence is a similar design and it was a sod for coming loose. (Although I suspect it was user error .) Do you need 8mm and 10mm allen keys to fit it?

Stevo_666

Not sure about that as I just chucked the bike into the local Cycle Surgery and asked them to fix the problem. They pointed out the bolts which seem to be very hard to access without removing the cranks. Will have a look tonight when I get home as I'm travelling by train today...

cjcp

I think you have to stick at least one allen key "into" the chainset and tighten it that way. There, on mine anyway, there's a cap you screw on/tighten separately.

Stevo_666

You're right - mine takes an 8mm Allen key. Out of interest, why did you want to know that?

cjcp

It looks a similar design to my RaceFace chainset and wondered if it was just as much a right PITA!

Stevo_666

Time will tell for me but I'm not off to a good start as the bike is less then 2 months old !