Cycling UK Forum

Thanks for all your answers - next stop will be to ask the shop!

I have bought a new Trek 7.2fx whose pedals turn when I push the bike. When I'm riding the bike and keep the pedals still the freewheel makes a loud 'ticking' sound. Is this a fault or is it simply because the bike is new? The rear hub is a shimano fh rm30 8-speed.

thanks rootes - loctite 641 seems to be the product - does anyone know where to buy it? i've found it online at bearingshop uk, but does anyone kow where I can buy it over the counter in Brighton or London?

Mick F wrote:

fixer wrote:A crank greased and tighten once to 35 - 40 Nm, should stay put.

I reckon you're right, but I feel the grease/dry argument will never go away! We've argued about it on here on more than one occasion.
I put mine on dry-ish - hedging my bets!

I quote from Mr Campagnolo's instruction sheet:
Note:
Before you assemble the cranks on the bottom bracket axle, degrease the axle and crankset square heads thoroughly.
NEVER lubricate the bolts before tightening them.

What does Mr Shimano say?

I suppose what applies to Mr Campognolo's beautifully engineered brand new components might not apply to the ancient, corroded and worn components of lesser manufacturers

Hi Mick F - I suppose "when something starts to stretch or fail, it won't get better, only worse" is a corollary of the Second Law of Thermodynamics - and Sod's Law too

Fixer - you say "The bolt doesn't actually unscrew; the crank gets tighter up the axle taper from the pedalling action" - but in my case the crank doesn't getting tighter; it starts to wobble.

I suppose loctiting is the opposite of what you do (ie greasing) - is there a risk that I'll stop my crank loosening but then will then find I can't get it off if I ever need to?

Thanks Mick F - the guy who was talking about case hardening is a motor mechanic - so he probably made a wrong assumption.

I'm back in France where my bike is later in the week, so the Loctite will be flowing. Watch the shares go up!

I'm intrigued by what you say: " ... maybe the crank has gone on so far in the past that subsequent tightening is moving it further and further up the taper" - are you saying that once it starts moving up the taper it will tend to continue? why would this be?

Thanks Mick F and pete75. Someone I asked yesterday said that what might be happening is that the case-hardened surface of the metal (surrounding the hole in the crank) has worn away, exposing the softer metal below - so rather than the bolt undoing what is happening is that the hole keeps getting bigger. Is this really likely?

I'd like to thank all contributors for answers so far. Some solutions just won't be open to me. This is an ancient and obsolete Viscount Aerospace bike, with idiosyncratic components, so buying a new crank is probably out of the question. Some people seem dubious about Loctite Threadlock. But is it worth trying? Can it do any harm? Also, might a lock washer help at all - and could that do any harm?

Thanks everyone (yes Mick - I posted it in the wrong place at first so thanks for deleting that)

Interesting question, Mick - I'll try to work out what's going on here. I suspect getting a new crank might be easier said than done - this is an old Viscount Aerospace Sport (late 70s vintage) with some rather idiosyncratic equipment.

I can tighten the left-hand crank nut (clockwise) to stop the crank wobbling but it soon works loose again. Could a lock washer be used to stop this?

Hi. I have a Viscount Aerospace Sport which I think I bought in the 1970s. The left hand crank keeps coming loose. A French bike repairer says there is some 'product' he can use to stop this happening. Is this plausible? Or will it be possible to find a new crank that will fit?

Also, I'd like to replace the drop handlebars with straight handlebars and replace the saddle - will there be a compatibility problem with current fittings?

Thanks for your help