Help! My gears are slipping

[Shaun]

Spesh Sirrus 07 - triple - slips when I set off from a standing start.

So much so, that I now have to nurse the bike out at junctions and take extra long before pulling out because I'm nervous of getting mowed down.

What's the probable cause?

Cheers,
Shaun

 

[MichaelM]

Does you chairing resemble a ninja death star?

More info needed - when setting off in all gears? Only on one chainring or two (all three) ?

 

[Shaun]

Does you chairing resemble a ninja death star?

Not sure actually ... I'll have to take a look tonight.

For some reason though, I got the impression the slippage was at the rear end. Could just be my perception of it though, so I'll take a look ...

Thanks for the quick response.

Cheers,
Shaun

 

[Shaun]

Middle chain ring - but then I pretty much stay on that one all the time when commuting; and usually largest rear cog as I tend to change-down each time I come to a stop.

Does feel like it's grinding a bit in some of the higher gears as well though.

 

[MichaelM]

try this - hold the bike stationary with brakes on. Press on the pedals - does your crank spin round making hell of a racket?

 

[Shaun]

try this - hold the bike stationary with brakes on. Press on the pedals - does your crank spin round making hell of a racket?

I'll let you know later ...

 

[4F]

try this - hold the bike stationary with brakes on. Press on the pedals - does your crank spin round making hell of a racket?

My money is on yes, sounds like new chain, ring (s) and cassette time.

 

[gbb]

Possibly your freehub...on the plus side, if it is, its relatively cheap...cheaper than cassette / chains etc

 

[Shaun]

Possibly your freehub...on the plus side, if it is, its relatively cheap...cheaper than cassette / chains etc

Is that something the LBS will be likely to have in stock and be able to swap-out quickly enough?

I'm off the Centre Parcs with the family shortly and want the bike behaving itself by then.

(It's a times like this I curse my lack of mechanical skill!)

 

[4F]

How many miles have you cycled using the current chain ? Have you replaced it previously from new ?

 

[Shaun]

How many miles have you cycled using the current chain ? Have you replaced it previously from new ?

Not that many, and TBH it was only serviced maybe 50 miles ago (which is a couple of months because I haven't been out on it much) and it was after it came back that it started doing this.

I haven't had chance to go back to my LBS to speak to him about it, and just wondered if it was something simple I could sort in the shed at home?

A trip to Rob's may be on the cards ...

 

[4F]

Assuming you do not have a chain checker have a look at the Sheldon Brown page here

http://www.sheldonbrown.com/chains.html

and in particular this:-
Measuring Chain Wear

The standard way to measure chain wear is with a ruler or steel tape measure. This can be done without removing the chain from the bicycle. The normal technique is to measure a one-foot length, placing an inch mark of the ruler exactly in the middle of one rivet, then looking at the corresponding rivet 12 complete links away. On a new, unworn chain, this rivet will also line up exactly with an inch mark. With a worn chain, the rivet will be past the inch mark.
This gives a direct measurement of the wear to the chain, and an indirect measurement of the wear to the sprockets:

• If the rivet is less than 1/16" past the mark, all is well.
• If the rivet is 1/16" past the mark, you should replace the chain, but the sprockets are probably undamaged.
• If the rivet is 1/8" past the mark, you have left it too long, and the sprockets (at least the favorite ones) will be too badly worn. If you replace a chain at the 1/8" point, without replacing the sprockets, it may run OK and not skip, but the worn sprockets will cause the new chain to wear much faster than it should, until it catches up with the wear state of the sprockets.
• If the rivet is past the 1/8" mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.

 

[gbb]

Is that something the LBS will be likely to have in stock and be able to swap-out quickly enough?

I'm off the Centre Parcs with the family shortly and want the bike behaving itself by then.

(It's a times like this I curse my lack of mechanical skill!)

Can't say for sure of course, but i'd imagine so. Never done a freehub, but they look easy enough. Of course, you need to remove the casette and have an allen key for the f/hub.

I'd imagine any good LBS will change them in no time at all....assuming that IS the problem.

 

[Shaun]

Middle crank ring ...

He put my old one against a new one to show me where it was worn.

All hunky dory now ...
Thanks for the advice everyone.

Cheers,
Shaun