Rear mech cable advice

1964johnr

I have a Ribble GranFondo compact double and am having an issue in the big ring moving on to the biggest cog on the rear mech which is a 28. When I shift in to it, it doesn't slip in neatly and noise free. It seems to move in eventually, but only after some noise from the chain hitting the cogs on the rear mech and maybe needing a forcefull finger on the shifter. I assumed it is the mech cable stretching after 5000 miles and needing tightening. I put the gearing in to the smallest gear on the small ring and undid the cable securing nut and tried to pull the cable through to tighten it, but I can't pull it any tighter and the problem persists. Any ideas on how to pull the cable tighter or do I need a new cable ?

redvision

Don't cross chain! You shouldn't be using big ring and big cassette sprocket together.

StillGoing

It's your mech protesting at your unsympathetic use of the gears. Stop cross chaining big to big.

pilot_pete

Does it shift correctly into the 28 when you are in the small front ring?

Cross chaining is not to be recommended, but I’ve never found it to prevent getting into the biggest cog, merely that the ‘protest’ is more of a noise due to the extreme angle and usually from the chain touching the inside of the front derailleur cage.

If your set up hesitates shifting into the 28 when on the small chainring then it could be either indexing or more likely limit screw adjustment.

PP

Alejandrosdog

like wot Pete said. Check the limits screws first if the rest of the gear changes are fine.

redvision

Alejandrosdog wrote:

like wot Pete said. Check the limits screws first if the rest of the gear changes are fine.

Or just don't cross chain and put unnecessary stress on the chain.

svetty

If pulling the cable taut, then adjusting the cable tension via the adjuster isn't resolving the problem it may be that you have knocked the mech and bent the hanger - hence the limit screws are not correct.

Start from scratch. Get the hanger aligned then reinstall the mech using the sticky on this forum. Or take it to a mate who knows what he is doing........

1964johnr

I'd never given cross chaining a thought. I have been riding on the same chain and block for 5000 miles and always used the big ring with the 28 at the back. I checked the cassette and it looks fine. Chain ware is almost at the point of needing a new chain. No crashes, so don't think it is a bent hanger.

pilot_pete

5000 miles on a chain is quite a lot, depending on your power and how hard you are on your running gear. When you say it is ‘almost at the point of needing a new chain’ what exactly do you mean? Have you used a chain checker, or measured it with a steel rule etc? Chain checkers are cheap and easy to use, but you want to be changing the chain well before it falls completely in unless you are planning to wear out your cassette and change both together at the next swap.

Cross chaining will put extra stress on the chain, especially if you are pushing hard on the pedals, which will cause premature wear on your components, which is why I think 5000 miles sounds like a lot on your chain, but I don’t know how hard you are riding so this is just supposition.

If your chain is well worn it could well be leading to less than optimal shifting. A new chain may solve it, but if your cassette is well worn then a new chain may behave even worse and require a new cassette to work correctly.

So like I said before, check if it shifts correctly when in the little ring up front in the questionable cogs at the back. Check the limit screw and the hanger for straightness (doesn’t matter that you have not crashed it - even a brand new hanger should be checked and possibly adjusted to ensure correct alignment - and you can’t tell purely by looking at it unless it is obviously bent/ damaged. These plus indexing and B Screw check/ adjustment are the cheapest checks. If that doesn’t solve it you are probably looking at a new chain and possibly new cassette.

I’ve had a Dura Ace chain which was hardly worn at all according to my chain checker doing little skips on a couple of the rear cogs and being quite noisy. Tried everything before eventually fitting a new chain which solved the problem.

PP

darkhairedlord

cross chaining, although not "recommended" should still go in on big-big. Big-big puts less stress in the chain than small-small. You need to adjust the B-screw, but the chain itself might also be too short.

N0bodyOfTheGoat

For a lot of riders, 5000 miles on the same chain means at least a new chain and cassette, if not new chainrings (which is often cheaper to buy as a complete chainset for the newer Shimano models) as well.

1964johnr

Thanks for the replies. Shifting on to the 28 at the back while in the small ring works fine. I have a chain ware tool which is showing that at 0.5 it slips in the gaps between the links, but doesn't quite drop in the gap at 1, hence my thoughts that it is nearly time for a new chain. I am a spinner and rarely churn a high gear which I guess is why the chain has lasted so long.I will check the H and L screws and the B screw and inspect the hanger. I have tried re indexing, but to no avail.

mankybianchi

darkhairedlord wrote:

Big-big puts less stress in the chain than small-small.

How so?

pilot_pete

1964johnr wrote:

Thanks for the replies. Shifting on to the 28 at the back while in the small ring works fine. I have a chain ware tool which is showing that at 0.5 it slips in the gaps between the links, but doesn't quite drop in the gap at 1, hence my thoughts that it is nearly time for a new chain. I am a spinner and rarely churn a high gear which I guess is why the chain has lasted so long.I will check the H and L screws and the B screw and inspect the hanger. I have tried re indexing, but to no avail.

The other possibilities once you have checked all those things are as others have said, such as is the chain length correct? If you fit a new one (which I would recommend at 0.5 wear, especially if 11sp), I would follow the Dealer Manual guidance (assuming it is Shimano) to ensure your chain is long enough. On big/big a chain that is too short is going to really stress the chain and affect the shift into the biggest rear cog. Here is the Park Tool guide to chain checking https://www.parktool.com/blog/repair-help/when-to-replace-a-chain-on-a-bicycle

PP

darkhairedlord

MankyBianchi wrote:

darkhairedlord wrote:

Big-big puts less stress in the chain than small-small.

How so?

T=FxD innit.
Torque through the crank is the same whether big-rig or small-small; since the distance to the teeth from the axle is greater on big-big then the force at the teeth (and chain) will be less.

darkhairedlord

Pilot Pete wrote:

1964johnr wrote:

Thanks for the replies. Shifting on to the 28 at the back while in the small ring works fine. I have a chain ware tool which is showing that at 0.5 it slips in the gaps between the links, but doesn't quite drop in the gap at 1, hence my thoughts that it is nearly time for a new chain. I am a spinner and rarely churn a high gear which I guess is why the chain has lasted so long.I will check the H and L screws and the B screw and inspect the hanger. I have tried re indexing, but to no avail.

The other possibilities once you have checked all those things are as others have said, such as is the chain length correct? If you fit a new one (which I would recommend at 0.5 wear, especially if 11sp), I would follow the Dealer Manual guidance (assuming it is Shimano) to ensure your chain is long enough. On big/big a chain that is too short is going to really stress the chain and affect the shift into the biggest rear cog. Here is the Park Tool guide to chain checking https://www.parktool.com/blog/repair-help/when-to-replace-a-chain-on-a-bicycle

PP

Chain measures that drop in are no good. You really need to measure between pin centres.

redvision

darkhairedlord wrote:

Chain measures that drop in are no good. You really need to measure between pin centres.

Nonsense, they work absolutely fine.

However, you do need to use a 0.5/0.75 checker as the chain should be changed at 0.75 on 8/9/10 speed chains, and 0.5 on 11/12 speed)

https://youtu.be/EJfTulNH4sk

pilot_pete

Hmmmmn. According to Park Tool, in the article I linked to previously, “the easiest and most accurate way to determine chain wear is by using a tool such as the CC-3.2 Chain Checker or the CC-2 Chain Checker.” I’m inclined to believe the industry’s leading tool manufacturer as their reputation regarding tools and maintenance is highly regarded.

They also say “Another ballpark method for checking chain wear is by measuring it with a ruler”. ‘Another’ refers to the method of pulling the chain away from the chainring and looking for daylight.

A precisely made gauge which can show the wear across several links consistently has to be more accurate than holding a steel rule against a chain and using your eye to align it with the pin centres, no matter how good your eyesight. And when you say they are no good and you have to measure across centres, what do you think the drop in type is measuring and why are they not accurate?

PP

mugensi

You don't mention anywhere if using the barrel adjuster at the rear mech helps or not?

But like others have said, your chain must be well worn at this stage regardless of whether your a spinner or grinder.

1964johnr

Thanks for all of the info. I went through a few of the suggested checks and came up trumps with a half turn on the L screw. The chain shifts in tot the 28 with no problems. I checked the chainwear again and it is somewhere between 0.5 and 0.75, so will purchase a new chain. I can't believe I have been cross chaining for 5000 miles without even thinking about it.