Shifting problem

Plissken

Hello people.

First I want to say I'm new to cycling, and I will try to explain my problem as best as I can.

About 3 months ago, I bought a used bike, Cannondale CAADX Tiagra (2013), from a guy who wasn't the original owner judging by his knowledge of the bike and its history. Apart from few scratches bike looked awesome, but while I was riding it I had some shifting issues, it's like the rear derailleur had a mind of his own, choosing not to shift, or jump gears etc.
I brought it to local bike shop to check and service the whole bike, and after a 2-3 day they called me back, to pick up a bike. They said, they checked everything, and that the everything was fine, apart from shifting. The guy told me that the rear derailleur and cassette are not compatible, and that he can't index the gear and he think I need the new cassette.
Now after I came home I saw that I had SRAM cassette 11-23 on my Tiagra (4601) rear derailleur. After a couple of day of internet research I found out that my rear derailleur and cassette indeed are not compatible. Tiagra support 11-25, 12-28 and 12-30 cassettes.

So my question is, is there anyone with the similar problem and what is the best solution?
I want to be sure it's cassette before I spend 50-60 euros on a new one.

Thanks in advance.

drlodge

You have a 10 speed rear derailleur, which will work with a SRAM or Shimano 10 speed cassette. A 23 cassette should be no issue, although the 'b' adjustment screw may need adjusting.

I would do 2 things to check this out
a) make sure the rear derailleur and hanger are perfectly in line, you need a gear hanger alignment tool for this and is something you could use quite often as hangers easily go out of alignment.
b) Once aligned, take the chain off and see how the rear derailleur jockey wheels line up with the sprockets at both extremes and at the middle of the adjustment, tweak the cable barrel adjuster as needed. (Use KMC quick link to join chain)

This will check that everything is aligned and adjusted correctly

shirley_basso

Generally speaking the gearing range shouldn't be a major issue if the rear mech will support it (i.e 11-23 or 12-30 shouldn't matter too much), but the number of gears is critical for it to work. SRAM and Shimano cassettes are 100% interchangeable across all speeds i.e any 9 speed SRAM Cassette will work on a 9 speed Shimano groupset etc and the same holds true to 10 and 11 speed systems.

I assume it's a 10 speed Tiagra groupset as you say its 4600 series (9 clicks on the RH shifter) in which case the cassette also needs to be 10 speed and I *think* the derailleur needs to be 10 speed as well.

Re: Rear mech support - there are short cage (SS) and long cage (GS) rear mechs for most Shimano groupsets. The cage is the part with the 2 jockey wheels inside. A longer cage rear mech are designed for wider range cassettes, up to 32 teeth or more, whereas a short cage rear mech typically shouldn't go above 28T.

drlodge

Shirley Basso wrote:

.... the cassette also needs to be 10 speed and I *think* the derailleur needs to be 10 speed as well.

This prompted me to recall...rear derailleurs are not 9, 10 or 11 speed, the indexing is provided by the shifter. So in theory, any Shimano rear derailleur with the correct pull ratio should work. So I cannot think how the rear derailleur cannot be compatible.

slowbike

drlodge wrote:

Shirley Basso wrote:

.... the cassette also needs to be 10 speed and I *think* the derailleur needs to be 10 speed as well.

This prompted me to recall...rear derailleurs are not 9, 10 or 11 speed, the indexing is provided by the shifter. So in theory, any Shimano rear derailleur with the correct pull ratio should work. So I cannot think how the rear derailleur cannot be compatible.

Hmm - they are - although the variants may be tiny - the shifter does pull a set amount - but the amount the mech moves in/out by is set by the mech itself - not the shifter - it's just reacting to a set amount of cable pull/release.

In my experience - bad shifting is usually down to the cable, then the cable routing - I've got a bike with bad shifting and it's down to the bottom bracket cable guide that is partially worn - gripping the cable instead of releasing it - so shifting up is (mostly) fine, shifting down needs additional release.

shirley_basso

Basically the movement of the shifter cable isn't a simple 1:1 ratio with the movement of the mech.

I can't recall all the details but I think it is the case that not even all 10 speed shimano systems are cross compatible (I think i read that 4700 shifters won't pull a 4600 mech the same distance as a 4700 mech due to the different pull ratios.

EXAMPLE:
The 4700 derailleurs are interchangeable with 5800/6800/9000 and now even 9100. Remember that pull 'ratio' is a two part equation. Just because the derailleurs use the same design lever arm, doesn't mean the shifter does... So the 10sp cassette in use on the 4700 group shares the same spacing as previous 10sp groups because the shifter itself has a pull that complements the derailleur to make it work.
So a 4700 shifter on said derailleurs will only work with a 10sp cassette, and the 5800/6800/9000/9100 shifters will work with 11sp cassettes even when paired with a 4700 derailleur.

keef66

2013 bike would have come with 10 speed Tiagra 4600. So if you have 10 speed shifters and a 4601 rear mech, it should work flawlessly with any 10 speed Shimano or SRAM cassette up to 28t. Have you actually counted the number of sprockets on the cassette? Is it firmly attached?

A worn cassette would cause the chain to jump forward under load in certain gears, but it wouldn't affect indexing.

Either there's something wrong with the cabling, or the mech hanger is bent. But any decent bike shop should have checked both.

Poppa Wheelie

Slowbike wrote:

In my experience - bad shifting is usually down to the cable, then the cable routing.

+1 a 'tight' cable can cause all sorts of shifting issues. Give it a good lube especially as it leaves the chainstay to go to the rear mech. If you notice ANY improvement, change the cable as the issue may well keep coming back.

keef66

Shirley Basso wrote:

Basically the movement of the shifter cable isn't a simple 1:1 ratio with the movement of the mech.

I can't recall all the details but I think it is the case that not even all 10 speed shimano systems are cross compatible (I think i read that 4700 shifters won't pull a 4600 mech the same distance as a 4700 mech due to the different pull ratios.

EXAMPLE:
The 4700 derailleurs are interchangeable with 5800/6800/9000 and now even 9100. Remember that pull 'ratio' is a two part equation. Just because the derailleurs use the same design lever arm, doesn't mean the shifter does... So the 10sp cassette in use on the 4700 group shares the same spacing as previous 10sp groups because the shifter itself has a pull that complements the derailleur to make it work.
So a 4700 shifter on said derailleurs will only work with a 10sp cassette, and the 5800/6800/9000/9100 shifters will work with 11sp cassettes even when paired with a 4700 derailleur.

Correct! 4700 is the one that catches most people out because it's still 10 speed, but the shifters and rear mech have the new pull ratio. The other groupsets adopted the new ratio as they went to 11 speed.

Another minor annoyance is that the 4600 10 speed cassette doesn't need the 1mm spacer that the other 10 speed Shimano cassettes do on most freehubs

Bumo_b

Having purchased a 4700 rear and fitting it to the bike with 4600 shifters, I can tell you it does not work, especially on the middle range of gears ie 4-7 due to the ratio. Changing the front shifter to 4700 sorted the issue, I was trying to upgrade on the cheap
Worth reading this
https://forum.cyclinguk.org/viewtopic.php?t=104359

Plissken

Thanks guys for the help, I'll try some of your suggestions when I come home from work
Also I forgot to mention, sometime there is a sound like something is breaking, really unpleasant, when I want to change a gear, and It would happen both when shifting up and down.

keef66

Is the noise at the same time as a crunchy feeling in the lever when you change? If so, it's likely the cable fraying inside the shifter, and you should replace it ASAP and certainly before it breaks.

If the noise is from the rear mech / cassette, maybe it's just the indexing needs adjusting. (but I still can't believe the bike shop couldn't sort it...)

drlodge

Good point, could well be the cable frayed inside the shifter...replace right now.

Plissken

I'm pretty sure that the noise coming from down, but I'm not sure from where because I tend to look straight when I change gears but yes it has that crunchy feeling. Also this reminds me (could be helpful), the problem with shifting occurs when I'm riding the bike, especially the crunchy noise, more than when the bike is stationary.

photonic69

Sounds like you need to find s new LBS if they took 2-3 days to service it and can't diagnose a problem with the shifting. I hope you didn't pay much (if anything).