Smoother Rear Mech Changes Is There Anything I Can Do?

[Cletus Van Damme]

I have a Marin Mill Valley 2004 that I bought off a mate for a reasonable price, it has Tiagra derailleaur's, 9 speed. I have mainly been using my bike on a turbo trainer due to the crap weather as part of a muscle strenghtening workout following a major knee op. It's just that the changes are not that smooth on the rear mech, and when changing under load it's jerky-ness sometimes irritates my knee slightly. It has always been like this even after having a gear service at a LBS. There also appears to be more mechanical catching/clattering kind of noises when I am on the highest 3 gears on the rear mech (this is not coming from the chain catching the front mech). I have messed about trying to trim the gear change using the cable adjusters but still cannot get it to change fairly smoothly, and also checked the high and low limits. I have a chain checking tool and the chain appears to be fine, the cassette does not have any obvious signs of wear. The rear derailleur also appears to be moving pretty freely and fast with gear changes. I guess it could be all kinds, or maybe the Tiagra is not the smoothest of rear mechs anyway? Just wondered if anybody had any pointers please? I really prefer to learn how to do things myself and have done fairly major jobs on cars before when I was younger. Although as a last resort I would take it to a LBS.

 

[dellzeqq]

Just a thought - check the drop-out. If it's been bent then it needs straightening. 'Straightening' is easier said than done - it needs a giant lever thingy that threads in to the dropout. And they can snap....

 

[MacB]

Just a thought - check the drop-out. If it's been bent then it needs straightening. 'Straightening' is easier said than done - it needs a giant lever thingy that threads in to the dropout. And they can snap....

There is a danger of it breaking but you don't need a fancy alignment tool. My LBS gave me a bit of threaded rod and I just used a hollow tube over the top of that. It didn't need much force at all, the tube I used wasn't very long(bit of an old metal curtain pole) and I just aligned by sight.

 

[rockyraccoon]

How is it on the road? Do you have the same problems?
my RD is shimano 2300. My bike is brand new.. everything works fine when on the road... smoth as it should be.. however when using the turbo trainer I have the exactly same problems.. the pressure under load is so much it seems like the chain will snap any time when changing gears. The more load is applied the more difficult it is to change gears. I also get the same kind of noises when I am on the highest 3 gears on the rear mech... I tried everything from adjusting cable tension, limit screw, bent rd, wear, etc; but as I said, on the road everything is fine. As soon as I'm on turbo trainer under load especially on the lowest gears all the problem starts..

 

[Cletus Van Damme]

[QUOTE 1286545"]
If by the three highest gears do you mean those with the smallest amount of teeth e.g 7th, 8th and 9th on a standard 9sp cassette? Then it could be that the b-screw needs adjusting. This screw increases the gap between the jockey wheel and cassette.
[/quote]

Yes that's what I mean, I will take a look at this. Thanks for all the replies, hopefully the dropout is fine the alignment of the jockey wheels to the corresponding cassette cog seems pretty good. Cheers User3143 for the numbered instructions, I will start again using those instructions.

Rockyraccoon, the bike was similar on the road, but maybe not quite as bad. I do not use the trainer on it's highest tension as I do not have the muscle strength, but I do fairly go for it I guess.

 

[rockyraccoon]

Please Cheesney HawksToday let us know the results.. I've tried everything but the BB adjustment... I will try that on my.

 

[Cletus Van Damme]

Yeah no bother mate if I get chance to have another mess around tonight I will. The other thing I have noticed with my bike is that the cassette has slight lateral movement, moving from side to side when spinning. Not a great deal but it does have some, it is not as much as the front chainrings have. I just do not know how true these are supposed to be, with this being the first half decent bike that I have had for years.

 

[mickle]

Oil the H & L screws Lee? Why?

 

[mickle]

MacB, With respect I don't think it is possible to do more that a half arsed job of straightening a hanger with out the proper tool. As someone who's tried it. And is equipped with 'protractor-vision'.

 

[PpPete]

friction shifter would seem ideal on a turbo ? not that I've used a turbo

 

[rockyraccoon]

The other thing I have noticed with my bike is that the cassette has slight lateral movement, moving from side to side when spinning... I just do not know how true these are supposed to be, with this being the first half decent bike that I have had for years.

Do you mean wobbling like this in this video from youtube? Because my does that as well. I also do not know how true they are supposed to be.

[media]
]View: http://www.youtube.com/watch?v=7lPAlF_d6tE[/media]
​

 

[mickle]

Do you mean wobbling like this in this video from youtube? Because my does that as well. I also do not know how true they are supposed to be.

[media]
]View: http://www.youtube.com/watch?v=7lPAlF_d6tE[/media]
​

They *all* do that. Nowt to worry about.

 

[mickle]

[QUOTE 1286556"]
Because they are made of steel and they rust/seize thus comprising the movement of the mech.
[/quote]

They are supposed to 'compromise the movement of the mech' it's what they do, they are limit screws.

Unless you intend to move the mech to another bike at some point in the future once they are set they are set.

You wrote it as if it's part of a regularly occuring maintenance programme. I've never 'oiled' a limit screw. Doing so serves no useful purpose. You're likely to confuse people with this sort of half thunk advice.

IMHO

 

[Zoiders]

Stop trying to change under load.

Spin - Don't mash the gears as you try to change them, you would not belive how many people I have seen who become convinced that their derailuer gears are "broken" when in fact they are not shifting correctly.

Simples.

 

[Cletus Van Damme]

Stop trying to change under load.

Spin - Don't mash the gears as you try to change them, you would not belive how many people I have seen who become convinced that their derailuer gears are "broken" when in fact they are not shifting correctly.

Simples.

Cheers this makes sense, I am a bit of a cycling noob. Just out of curiosity, due to my knee problem I have thought about changing the rear cassette for something with a bigger lowest gear cog as I sometimes ride the bike with my 19 month old daughter in a child seat. Even small hills kill me as I am not able to get off the saddle. My bike has a rear cassette that has 12 - 26 teeth and the front chain ring is 30/42/52 teeth. Anybody have any idea what size of teeth I could go upto on the rear cassette without having to buy a MTB type derailleur. I obviously know that I would have to get a new chain too.