How to adjust gears?

[Deleted member 20519]

As stated above...freehub is the cause of the temporary slack chain. I had the exact same problem.
Lubing might help as a short-term fix. How old is the back wheel?

Less than a month old, came with my new bike. Reckon I should take it back to Decathlon? It's covered under warranty.

 

[ushills]

Take it back, may be a faulty freehub. The one on my pinnacle failed after about 6 months and I build new wheels as they were poor anyway.

 

[Deleted member 20519]

Take it back, may be a faulty freehub. The one on my pinnacle failed after about 6 months and I build new wheels as they were poor anyway.

I'll give Decathlon a call today and see what they say.

 

[Maz]

Less than a month old, came with my new bike. Reckon I should take it back to Decathlon? It's covered under warranty.

Woh, that doesn't sound right. Could be freehub is faulty.

 

[simon.r]

The issue with the gears is that when I'm pedalling and stop, the chain goes into ultra-slack mode and loses all of it's tightness and then it takes half of a pedal revolution before the chain tightens up again and I can continue pedalling. I'm fairly sure this can be fixed with a simple derailleur adjustment but there's one problem - I don't know how.

It does sound like a freehub problem, but it could be worth checking how close the rear mech is to the cogs. If it's rubbing this would explain the grinding noise and, I think, the slack chain. Look at the 'B-Screw Adjustment' section about half way down this page: http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur

 

[Deleted member 20519]

It does sound like a freehub problem, but it could be worth checking how close the rear mech is to the cogs. If it's rubbing this would explain the grinding noise and, I think, the slack chain. Look at the 'B-Screw Adjustment' section about half way down this page: http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur

It can't be a problem with the derailleur because it's only when I'm freewheeling = nothing's moving except the wheel (the casette, derailleur etc is all still).

 

[simon.r]

It can't be a problem with the derailleur because it's only when I'm freewheeling = nothing's moving except the wheel (the casette, derailleur etc is all still).

It could be that when you're pedalling you're applying enough force to pull the derailleur away from the cassette? Impossible to say without seeing the bike, but I'd be tempted to have a quick look at the rear mech position.

I find it's often worth taking 5 or 10 minutes to have a thorough look at the bike and see if there's anything obvious, before starting to take things to bits!

Although, as others have said, a freewheel problem is more likely.

 

[Deleted member 20519]

I've had my bike upside down and I've got some more info. When I'm pedalling, everything's fine but when I start free wheeling, sometimes the cassette 'catches' the wheel and spins, this obviously moves the pedals but when I'm on the bike, my feet won't be moving so the casette will be going forward and that's what's making the chain slack. Is it possible that the cassette is rubbing against the hub and catching?

 

[Broadside]

Is the cassette catching on something that you can see such as a spoke or on the pie plate?

If not then it is a problem internally, I have to say that freehub is either gunked up or knackered. Did you take the bike back to Decathlon yet? I think that it your next step.

 

[simon.r]

Agree with above. Not trying to teach you to suck eggs, but what you almost certainly have is an arrangement similar to what's shown here (on the right) -

The cassette slides onto the freehub (the bit marked 'splines'), which then fastens to the hub. This is the freehub on its own:

The freehub is the bit that allows you to freewheel when not pedalling, but engages 'drive' when you do pedal. It sounds as if it's trying to enage drive (or 'catching') when you're freewheeling.

Take it back to the shop, or, as others have said, try and clean the freehub out with WD40 or similar (you need a spray can with a straw to force the WD40 into the freehub).

Personally I'd take it back.

 

[Rob3rt]

Take it back to Decathlon, tell them the freehub is farked, they will most likely replace it!

 

[fossyant]

Go back to DECATHLON. They will most likely fit a new wheel for you ! No messing.

 

[Deleted member 20519]

Hey guys, Decathlon have told me that they'll look out a wheelset for me and replace them tonight if I come down. Heading down around 7.

Edit: Decathlon replaced and fitted the new wheelset, no questions asked. All gear issues now sorted!