New cassette and chain?

livpoksoc

Über Member
Location
Basingstoke
After a decent year of going from mot using my bike to clearing 900 mile since lockdown, I'm wondering if I need to replace the chain and/or cassette.

I've had the bike up on the workstand and indexed using th barrell adjusters but wasn't completely satisfied it was perfect, but on the road it's worse. It's rideable, but the odd change up or down seems to need a couple of clicks and then a correction click back to get it where I want, and once today under load it changed up on me in a hill.

Changing the chain and/or cassette looks simple enough and I have the tools but never actually done it. Just wondering if there's a sure fire way to work it out first if the job needs doing at all. The bike has probably done 2k miles since new, half of that this year and it spent 2 years sat idle. It was serviced earlyish in lockdown by a locl chap who said it all looked fine at the time.

It's a 105 groupset (sora?) cassette.
 

lucidone

Active Member
Location
Near Bicester
Do you have a chain stretch/wear gauge? Cheap as chips and worth their weight in gold.
I'd start there and see what it says.
If you just want to go straight to work with Amoy you could just buy a new chain and try it - you're going to need one someday!
 

si_c

Veteran
Location
Wirral
There are a couple of likely possible causes - most likely it needs a thorough clean - chain and cassette, and then lubricate the chain slightly and dry it off. Follow this up by checking the indexing - there are plenty of good guides on the internet, but essentially at each gear position the chain and the two guide pulleys on the derailleur should be in a straight line when looking from behind the bike.

Also add some lubricant to the gear cables for the rear anywhere it enters the outer cable then run through the gears a few times - quite often you can get dust or dirt in between the outer cables and the gear cable itself - this causes extra friction meaning that the shifting isn't precise, lubrication helps here.

If not then there could be a couple of causes - check that the rear wheel is seated in the drop outs properly, if not then the wheel will be at a slight angle - causing mis-shifts. If you've been messing with the cable tension then it's most likely that this needs properly adjusting as mentioned above.

Lastly it could be a bent derailleur hanger - if the derailleur cage is not parallel with the wheel both vertically and laterally then this will also cause problems.

If you can't get it working then likely the best solution is to get it to a LBS and get them to change all the cables, reindex the gearing and check the derailleur hanger alignment.
 

I like Skol

I don't think so, sonny!....
Location
Room 237
It'll be your cables mate. Worn chains often run perfectly well on the correspondingly worn cogs. It is when you start mixing new & old that problems start. Sticking cables cause all sorts of funky shifting problems so I recommend you clean and oil them first. It's often worth replacing the short peice of cable casing at the rear that feeds into the mech as this section is the most exposed and has the tightest turn.
 

Gunk

Veteran
Location
Oxford
I think my money would be on dodgy cables. As above try lubricating or replacing first.
This would be my starting point, setting up indexing is a long laborious process, sometimes it’s taken me over an hour to a bike shifting properly, also on a stand it will shift properly and then on the road it won’t, I tend to use a turbo trainer as it puts the drivetrain under load.
 
OP
livpoksoc

livpoksoc

Über Member
Location
Basingstoke
Thanks all, very useful. Will give it a deep clean today and lube the cables to begin with.

I have a chain gauge on order.
 
OP
livpoksoc

livpoksoc

Über Member
Location
Basingstoke
It'll be your cables mate. Worn chains often run perfectly well on the correspondingly worn cogs. It is when you start mixing new & old that problems start. Sticking cables cause all sorts of funky shifting problems so I recommend you clean and oil them first. It's often worth replacing the short peice of cable casing at the rear that feeds into the mech as this section is the most exposed and has the tightest turn.
When you say 'clean', do you mean remove and wipe it down or just a wipe with clean cloth, then lube it?
 

Gunk

Veteran
Location
Oxford
It's often worth replacing the short peice of cable casing at the rear that feeds into the mech as this section is the most exposed and has the tightest turn.
I would definitely do this and make sure the curve in the outer cable isn’t too tight.
 

I like Skol

I don't think so, sonny!....
Location
Room 237
When you say 'clean', do you mean remove and wipe it down or just a wipe with clean cloth, then lube it?
Two ways to do this. One is to pop all the outers out of the guides and clean the cable with a rag and a solvent lube like GT85 or WD40. You then need to re-lube with a proper oil, my oil of choice for a long time has been Weldtite TF2 all-weather oil.

The other way is to remove the cable and blast out the cable casings with a solvent/oil (wd40 or GT85) then refit the cable with a good coating of oil. If you are doing this it is probably a good time to replace the cable inner anyway.
 
Location
London
I prefer to assemble dry, oil or grease tends to go sticky after a while
Yes, there is a theory that it interferes with/softens the lining on the outers, making things worse.
Being of a nervous uncertain faffy disposition i tend to compromise and just squirt a bit of gt85 at the end of the inner where it enters the outer. Where inners are exposed they get wiped with gt85 on a rag.
 
OP
livpoksoc

livpoksoc

Über Member
Location
Basingstoke
Ok thanks. Just gave the bike a thorough clean, had the chain off, soaked in chain cleaner, hosed off, wiped a billion times. Flossed the cassette, scraped the gunk off the jockey wheels and reassembled. Lubed and indexed with the barrell adjuster.

Will give it a little run out tomorrow to check if it helped.

If I'm replacing cables, I assume it's a new handlebar wrap job? (Not intern frame caes thankfully)
 

si_c

Veteran
Location
Wirral
If I'm replacing cables, I assume it's a new handlebar wrap job? (Not intern frame caes thankfully)
Not necessarily, the outers under the bars tend to get less dirt in them and last longer, if you don't want to replace those outers you can just feed a new cable through from the shifter end. It can take a few minutes to get it done first time, but you won't need to do anything with the bar tape. I've done this a number of times successfully.
 
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