Loose chain?

[Cletus Van Damme]

Firstly the Deore's angle looks a little odd - are you sure your B screw is catching the tap on the hanger like pic below?

Secondly I see absolutely no reason why the top jockey of a Tiagra rear mech would touch a 28T rear sprocket. Something is definitely not right.

Thanks for the reply mate. Yes the B screw is catching the tap, it is more or less in the same position as the one in the picture.

I possibly had the chain a couple of links too long with the Tiagra mech but it just looked hopeless so I tried the Deore one. It's a 9 speed Tiagra mech with a maximum spec of 27t rear cassette, but I thought it could of been pushed a little further. I do not know if it is the smaller inner chainring of 28t that caused it to mess up with a longer chain allowing for big chainring/big sproket combination. Thanks for the help mate.

 

[RecordAceFromNew]

I have attached some pictures below at various chainring/sprocket combinations to see what you guys reckon of the chain length. Thanks for any adivce.

I am sure the Deore has enough capacity to handle the range. Chain-wise the small small photo looks fine to me. There is no large large photo but if there is a bit of an S curve at the jockey wheels then length should be fine.

 

[Cletus Van Damme]

I am sure the Deore has enough capacity to handle the range. Chain-wise the small small photo looks fine to me. There is no large large photo but if there is a bit of an S curve at the jockey wheels then length should be fine.

Thanks again fot the great advice mate. Here is a picture of the Deore mech on large large:



I also put the Tiagra rear mech back on to see if it was better with a slightly shorter chain, but it looks like a no go to a numpty like me.

Small Small:

Close up of upper jockey wheel (small small) just about touching chain:

Small chainring/large cassette sprocket. With b screw adjusted as much as possible the jockey wheel and cassette sprockets are touching, not that clear in picture:


I was wondering my other bike a Marin Mill Valley has exactly the same setup as my Secteur (triple, same chainrings and cassette), although the long cage Tiagra mech looks a slightly different design to the one on the Secteur as it is a much older bike. What I was wondering are there any other 9 speed rear mechs around that I might be able to put on the Secteur that are maybe not quite as big/bulky as the Deore that should be able to handle the current setup of 50/39/28 chainring, 11/28 cassette. Then I would put the Deore mech on the Marin.

I also wondered how do you measure the chainstay length as I do not know the specs of a 2004 Marin Mill Valley ALP 19" frame. Just to use the chain length calculator again.

Thanks for any help, very much appreciated

 

[GrasB]

That rear mech looks to have wrap capacity left. I've just had a look at my race bike & it's chain is about 10mm lower than straight on big to big.

 

[Cletus Van Damme]

That rear mech looks to have wrap capacity left. I've just had a look at my race bike & it's chain is about 10mm lower than straight on big to big.

Sorry I am numb mate . Does that mean I could shorten the chain a little further with the Deore mech?

 

[RecordAceFromNew]

Sorry I am numb mate . Does that mean I could shorten the chain a little further with the Deore mech?

No. I wouldn't. Chain length limit has nothing to do with rear mech capacity. (Minimum) chain length is limited by large large. From the new large large photo, I am not sure you can take another pair of links out (and of course you can not take just one out physically). Your current chain length is likely spot on.

It is dead easy to measure "chainstay length" for chain length calc. It is the distance of the straight line between the centre of the crank axle to the centre of the rear axle.

 

[RecordAceFromNew]

With you setup, I think you need (50-28) + (28-11) = 39T capacity. It is clear the Tiagra can just about make it (because the bottom part of the chain is not quite touching the bottom of the top pulley when on small small, and the chain is not unduly slack), however it is very very close. I am pretty sure its official capacity is nothing like 39T.

The more important issue concerning the Tiagra in this setup is the sprocket is nearly (again) touching the top jockey wheel. That can likely be eased by screwing the B screw all the way in, and if still no good by reversing the B screw (see this) - I resort to this occasionally and it does work, but it is a messy job and I would only do it because e.g. I really need to keep a period correct premium mech working with a large sprocket it was never designed for. Here, the question is do you really want/need to in this case. Incidentally you can guesstimate how much difference e.g. a longer screw can possibly make by simply using your hand to wind the top arm of the rear mech back (which is exactly what a longer screw would do), you should see the clearance between the sprocket and top jockey grow.

 

[RecordAceFromNew]

I was wondering my other bike a Marin Mill Valley has exactly the same setup as my Secteur (triple, same chainrings and cassette), although the long cage Tiagra mech looks a slightly different design to the one on the Secteur as it is a much older bike. What I was wondering are there any other 9 speed rear mechs around that I might be able to put on the Secteur that are maybe not quite as big/bulky as the Deore that should be able to handle the current setup of 50/39/28 chainring, 11/28 cassette. Then I would put the Deore mech on the Marin.

What you are really asking in effect is whether there are lighter/slimmer mechs that have greater capacity and/or comparable capacity as the Deore. While neither up-to-date nor complete this is probably instructive. Comparing your Tiagra with the pic of the Tiagra in their site, it is possible that yours is a SS (short cage) not GS. A GS having official capacity of 37T should have no issue handling 39T. You should be able to check and confirm by reading the code on your mech.

 

[GrasB]

Sorry I am numb mate . Does that mean I could shorten the chain a little further with the Deore mech?

Why do a proper big to big & see how many links you can take out.

 

[GrasB]

No. I wouldn't. Chain length limit has nothing to do with rear mech capacity. (Minimum) chain length is limited by large large. From the new large large photo, I am not sure you can take another pair of links out (and of course you can not take just one out physically). Your current chain length is likely spot on.

I based my recommendation on this:

Thanks again fot the great advice mate. Here is a picture of the Deore mech on large large:

However I didn't twig he was using 2 different mechs.

We need to see big to big on the Tiagra

 

[Peteaud]

Its not the mech that governs it, its the hanger, or a fair degree of it anyway.


My 9 speed Tiagra is running a 30 tooth cassette, and i have had a 32 tooth on it just to see if it would work, the 32 was possible but too close to the limit for me (giant defy hanger)

Set the chain 1st big / big + 2 links.

 

[GrasB]

Its not the mech that governs it, its the hanger, or a fair degree of it anyway.

It's more the mech than hanger. Larger sprocket capacity mechs move the jockey wheel further from the axle. If you start offsetting the mech to gain sprocket capacity you tend to hit shifting problems at the small end of the cassette.

 

[Cletus Van Damme]

What you are really asking in effect is whether there are lighter/slimmer mechs that have greater capacity and/or comparable capacity as the Deore. While neither up-to-date nor complete this is probably instructive. Comparing your Tiagra with the pic of the Tiagra in their site, it is possible that yours is a SS (short cage) not GS. A GS having official capacity of 37T should have no issue handling 39T. You should be able to check and confirm by reading the code on your mech.

Thanks very much for taking the time with useful advice and info mate. I think I will just stick with the Deore rear mech as weight is not really an issue for me. Thanks again very much appreciated

 

[Peteaud]

Spesh roubaix has a sora running a 32 tooth cassette from the factory, shimano tech say max is 28 tooth. All spesh did was increase the hanger length.

2012 defy 2 runs a 30 tooth Tiagra as standard.


But that does not mean a sora will run a 32 on all bikes, or Tiagra will run 30.

It depends on the bike

I have also seen Di2 running a 32 tooth

 

[Cletus Van Damme]

Its not the mech that governs it, its the hanger, or a fair degree of it anyway.


My 9 speed Tiagra is running a 30 tooth cassette, and i have had a 32 tooth on it just to see if it would work, the 32 was possible but too close to the limit for me (giant defy hanger)

Set the chain 1st big / big + 2 links.

I did not know you could get 30t rear cassettes for 9 speed. If I did I would probably of went for one. Still at least if I keep the Deore mech I have more options in the future as I cannot handle hills with my bad knee.