Chain wear gauge - how to use and chain replacement

[TPMB12]

Bought a chain wear gauge and just double checking I'm using it right. You stick the end with two prongs on over the pin.area of the chain then dropping the single prong into the chain. If the single prong goes into a gap so the gauge rests on the chain then that wear figure applies. In the case of my gauge there's 0.075 and 0.1 I think. The first means the chain needs to be replaced soon. The second means replace now.

So my chain resulted in the higher number side of the gauge dropping straight into the gap in the chain without touching the chain. I guess this means my chain is definitely due for replacement like yesterday!

Is this right? Any other check I can.do? It looks in ok nick visually.

Other thing, how easy to change? What with the cassette change needed at the same time. How can you tell if the chainrings need to be changed or not? It's a year and a half bike and first chain. 10 speed Tiagra 2 Chainrings. I take it replace.like for like, but how many links needed? It's something like 52-32 chainrings and 12-28 cassettes.

[LittleWheelsandBig]

With that much chain wear, a new cassette is a certainty. The chainrings will be fine. Chains come 'too long' and are cut to length with a chain breaker. Match the same number of links as the existing chain (which will have worn longer than the new chain).

[T42]

Before you fit the new one, hang it up side by side with the old one. The difference in length will be quite striking.

[Ningishzidda]

A twelve inch ruler. 10.1” is ‘Worn out’.
Take the old chain off and lay it flat. Chop the new chain to match the number of links. This is where an old curtain rail comes in handy, to lay the filthy, greasy old chain flat.
Give the cassette and mech a wipe with a rag and then thread the new chain through. Fit the quick-link.

[TPMB12]

How easy is it to replace a cassette? Shimano Tiagra short cage I believe but not 100% sure.

I should have the tools to try, got the ALDI bike toolkit from earlier this.year. Supposed to be shimano specific I think.

If it's easy I'll try it, if not I'm probably 2 weeks or more without a bike while the bike shop near me does what I'm guessing is an hour's job at most. I know someone who got this sorted in 1.5 hours at Nevis Cycles having just turned up on the door. My local shop book you in with anything up to 4 weeks! The others nearby we've used had not the best work done before.

[PaulF]

Tiagra short cage will refer to your rear mech not the cassette.

Changing the cassette is a fairly easy job: wrap the chain whip round the cassette, insert the lockring tool into the lock ring and undo the lockring. The lockring may be a little tight but the hardest part is working out how to use a chain whip.

[Samuel D]

The hardest part is getting the lock-ring off, in my experience. They’re often ridiculously tight for reasons I haven’t figured out. If the Aldi toolbox has the right tools, there’s a decent chance they’ll bend doing this job. But you might as well try.

Very few chain-wear indicator tools measure the correct dimension, as explained here.

[PhilO]

There is  school of thought which says that once the chain has passed the point at which the cassette needs changing anyway, it's more cost effective to run what you've got to distruction before changing over.  As a rule, if the wear is between 0.75% and 1%, I fit a new chain. If it's over 1% then I get a bit more wear out of both before swapping. I do the same if a new chain skips  on the old cassette (old chain back on, run into the ground). 

YMMV, particularly given that my experience is mtb only, and hence I typically get only 5-700 miles wear out of a chain.

[DaveReading]

insert the lockring tool into the lock ring and undo the lockring. The lockring may be a little tight but the hardest part is working out how to use a chain whip.

It sometimes helps to put the skewer and nut back on after fitting the lockring tool, to make sure that the tool stays on the lockring as you try to loosen it.

[toestrap]

If you need more detail on cassette changing, the late great Sheldon Brown is your friend:

http://www.sheldonbrown.com/k7.html

Alternatively there are loads of good videos on you tube.

[Ningishzidda]

Some cassette lockring removal tools have a pin that fits down the hollow QR spindle.

To hold the cassette firm, I use a Stilson.

[Tim Hall]

A twelve inch ruler. 10.1” is ‘Worn out’.
Take the old chain off and lay it flat. Chop the new chain to match the number of links. This is where an old curtain rail comes in handy, to lay the filthy, greasy old chain flat.
Give the cassette and mech a wipe with a rag and then thread the new chain through. Fit the quick-link.

How many 12 inch rulers are marked in tenths though?  Half, quarter, eighth, sixteenth are more common. 

FWIW, there are 96 eighths in 12 inches, so when it's at 12 and 1/8th inches, that's 1 percent elongation, or something very close to it.
(Finding a 12 inch ruler with marks beyond 12 inches is left as an exercise for the reader.)

[Brucey]

(Finding a 12 inch ruler with marks beyond 12 inches is left as an exercise for the reader.)

surprisingly common, in fact.  A cheap stainless steel ruler (often available at the pound shop) will often do the trick.

BTW if you want to check that you are using a chain checker correctly, try it out on a new chain as well as a used chain.

cheers

[Ningishzidda]

Another check for chain wear is to lift a rivet off the very front of the chainring. This method has no tools or definitive rules. Its from experience.

[TPMB12]

I was already certain it's due for replacement. It's skipping, it feels looser on the chainrings than I remember it being. Feels like the summer tour in perpetual rain just finished it off(not due to rust ).

I'm curious, if I was to replace the cassette with a slightly different range what would I need to do differently with the chain? Currently running 50-34 chainrings and 11-25 cassette. Was wondering about increasing the teeth on the cassette slightly. I think i need more than the 25 to help with loaded rides on hills,  such as with trailers. Not sure I've got much room to do this with the short cage derailleur. Would I be able to increase the 25 without changing the derailleur? If so what are the likely options and what affect would it.have on the chain lengths/number of links needed?

[Bledlow]

Tiagra short cage will refer to your rear mech not the cassette.

Changing the cassette is a fairly easy job: wrap the chain whip round the cassette, insert the lockring tool into the lock ring and undo the lockring. The lockring may be a little tight but the hardest part is working out how to use a chain whip.

Decathlon sells a cassette tool which is much easier to use than a chain whip. £11.99. I have one, & I've changed a few cassettes with it.
http://www.decathlon.co.uk/chain-whip-cassette-remover-id_8309913.html?iv_=__iv_p_1_g_25792476056_c_93735700256_w_pla-158261012696_n_g_d_c_v__l__t__r_1o3x_pla_y_15177021_f_online_o_149219_z_GB_i_en_j_158261012696_s__e__h_9046111_ii__vi__&gclid=CjwKEAjwxeq9BRDDh4_MheOnvAESJABZ4VTqDGit1qmLzZnAT0_R1uTt8Gsb1nTh0FkRGzvcLQH06RoChufw_wcB

[Ningishzidda]

The usual way of getting the chain length correct is to run it on the big ring and small sprocket. When here, the wheel spindle and both jockey bushes should be in a straight line.

Using a larger basement sprocket, the tension jockey will be pulled more toward the chainrings. At the same time, the guide jockey may be pulled away from the sprocket teeth. Depends on where the cage pivot is in relation to the guide jockey.

[Ningishzidda]

Tiagra short cage will refer to your rear mech not the cassette.

Changing the cassette is a fairly easy job: wrap the chain whip round the cassette, insert the lockring tool into the lock ring and undo the lockring. The lockring may be a little tight but the hardest part is working out how to use a chain whip.

Decathlon sells a cassette tool which is much easier to use than a chain whip. £11.99. I have one, & I've changed a few cassettes with it.
http://www.decathlon.co.uk/chain-whip-cassette-remover-id_8309913.html?iv_=__iv_p_1_g_25792476056_c_93735700256_w_pla-158261012696_n_g_d_c_v__l__t__r_1o3x_pla_y_15177021_f_online_o_149219_z_GB_i_en_j_158261012696_s__e__h_9046111_ii__vi__&gclid=CjwKEAjwxeq9BRDDh4_MheOnvAESJABZ4VTqDGit1qmLzZnAT0_R1uTt8Gsb1nTh0FkRGzvcLQH06RoChufw_wcB

I still prefer a two foot Stilson. The weight of it helps. I permanently borrowed mine off my Father in law. 

[Bledlow]

It replaces the chain whip, not whatever you use to grip the lockring tool.

I use a big adjustable spanner to hold the lockring tool, & the other thing (calling a chain whip doesn't seem right, it being rigid) slots over the smallest sprocket. It fits 11, 12, 13 & 14 teeth, depending on which hole & which way round.

[Ningishzidda]

Yes, the two foot long stilson is used to grip the sprocket teeth. Easy-peasey.
A 12" adjustable spanner is used as the lever on the lock-ring tool.

[Bledlow]

Ah, I see.

[Ningishzidda]

I've just checked the price of a 24" Stilson.

£85 from Screwfix.

Maybe not everyone's best method.

Father in Law didn't ask for it back,,, 

[Kim]

The hardest part is getting the lock-ring off, in my experience. They’re often ridiculously tight for reasons I haven’t figured out. If the Aldi toolbox has the right tools, there’s a decent chance they’ll bend doing this job. But you might as well try.

I've been using an Aldi chainwhip and cassette lockring tool for years.  They're fine.

Some of the other tools in the kit are cheese and have since been replaced by Park.  The chain tool went straight in the bin, for example.  The crank remover lasted a lot longer than I expected, but finally mashed its threads earlier this year.

[Biggsy]

How can you tell if the chainrings need to be changed or not?

Just try them if you're not sure from appearance.  Chainrings tend to wear more slowly than cassette sprockets (though it also depends on material and size), so replace the chain and cassette, stay seated and ride the bike with gradually increasing pedal pressure and listen and feel for any skipping.  They'll be no urgency to replace them if there's no skipping.  Perhaps later a mechanic (or the YACF massiv via a photo) will advise if there's any need at all.

I'm curious, if I was to replace the cassette with a slightly different range what would I need to do differently with the chain? Currently running 50-34 chainrings and 11-25 cassette. Was wondering about increasing the teeth on the cassette slightly. I think i need more than the 25 to help with loaded rides on hills,  such as with trailers. Not sure I've got much room to do this with the short cage derailleur. Would I be able to increase the 25 without changing the derailleur? If so what are the likely options and what affect would it.have on the chain lengths/number of links needed?

Check the capacity and maximum sprocket specs for your particular model and year of derailleur (in manufacturer's instructions/website), add a pinch of salt if you dare*, and that's what you can have up to.  Each extra pair of chain links tends to enable a few extra sprocket teeth.  Start off with the chain longer than you think you need, join, test and shorten/repeat as necessary.

There are chain length calculators out there, but I prefer the trial and error or experience methods.  Ensure the chain is long enough for big-big (largest rear sprocket + largest chainring) IF you want it to cope with accidental shifting into this gear that you'd normally avoid.  It doesn't have to work nicely or look right in this combination, just work without breaking anything.

* Usually one to three teeth, sometimes more.  Have the chain as short as practicably possible if pushing the specs, otherwise the chain length is not so critical as there's some leeway when you're within the official specs.

[andrew_s]

How can you tell if the chainrings need to be changed or not?

If the chainring is likely to slip, it will look obviously worn, with the teeth at approx. 90° to the crank being pointed, rather than with flat tips.
If it does slip, slipping will damage the teeth so that it will slip much more easily next time. This can mean that you can't ride up any reasonable hill using that chainring.

A chainring that has slipped, ripping the tops off the teeth by the drop pin


A chainring & chain in imminent danger of slipping with the old chain. Observe the spaces between chain & chainring.