First road bike chain rub

olly64

Hi everyone. First post on your forum from a newbie to cycling. After riding a cheap mountain bike for the last five months and finally taking the plunge to buy my first road bike, after checking out the local Lbs's and nearly putting a deposit on a Giant Defy 1 but would have to wait until April for availability in my size, I went for a Giant TCR 0 2011 model with a better (Ultegra) groupset for a little over £1k from a reputable retailer with more than one shop that was 60 miles from home. Not a problem as I work in the area frequently. On my first ride I felt the chain rub whilst on the largest front cog and the three largest rear cogs and also the reverse, smallest front cog and the four smallest rear cogs.
I took it back to the, not so Lbs who checked it out and said there wasn't too much wrong with it, some bikes do this and are never really smooth in all gears, don't ride large to large and small to small and bring it back in 4-6 weeks for a check over when the cables have stretched a little. I am putting miles on after two weeks, weather permitting, absolutely loving the experience, apart from ending up in these gears that annoy me with the rattle.
Can anyone please advise me if this is actually correct that i may have to live with this situation and only use 2/3rds of the gears or should I be insisting the gears should run smooth in every combination.
Apologies if i have been rambling on or not posted this correctly.

Wirral_paul

Most will do this in the crossover large / large and small / small - but generally in the end 1 or maybe 2 gears only. 3rd largest sprocket on the big ring should be fine though. Probably just needs a tiny tweak on the front mech adjuster screws as they may be a little too wide on the gap at the small ring / big sprocket and big ring / small sprocket combo's.

Well worth learning to set the gears yourself anyway - plenty of guides on here and youtube

ba68

I have ultegra on my bike, 10 speed cassette and standard double chain set and can use the whole range with no rubbing so you (or you lbs) should be able to set it up to achieve the same Sorry if this is an obvious point but are you aware of the trim facility on the front mech?

rpd_steve

Just a thought... I noticed you said 'smalest' and 'laegest'. Can I assume you have a tripple crank from that? If so rub is unavoidable as the fromt mech cage is narrower. You will also not be 'loosing' any gears as there is considerable overlap between the chainrings, i.e. large chainring and 4th largest on back is about the same as small chain ring and 2nd smalest on back. Its made like that as the drive train is not made to work 'crossed' up - though depending on the setup (as above) it can - bikes on double and with long chainstays can get away with it.

In any case you should try to avoid it as you are trying to bend the chain twice and the result is faster wear all round. You will soon get the hang of clicking up a couple of cogs on the back when you move chain rings ect.

sandyballs

Firstly welcome to the club and secondly great choice of bike i have 2 Giants now and love them.

I would go with ba68 get used to the trim facility and look to adjust the set up yourself. Just take small steps and log each adjustment ie, half turn clockwise so that you can undo if going the wrong way and making things worse.

Happy riding.

itsnotarace

You will accelerate wear when cross chaining, it's best to avoid it where possible. Despite what the above posters have said, it's not the screws on the mech that need adjusting as that just limits the movement of the entire mech. What you need to adjust is cable tension and you would do this using a barrel adjuster

smidsy

itsnotarace wrote:

You will accelerate wear when cross chaining, it's best to avoid it where possible. Despite what the above posters have said, it's not the screws on the mech that need adjusting as that just limits the movement of the entire mech. What you need to adjust is cable tension and you would do this using a barrel adjuster

Actually a combination of both.

Front mech travel. With the bike in lowest gear (small cog on front and big cog on back) there should be about 1mm gap behind the chain to the rear plate of the front mech - adjust with the low speed screw.

With the bike in top gear (big cog on front and small cog on back) check that the chain does not touch the outer plate on the front mech - adjust with other screw so its just clear.

This stops rub and does not allow chain to fall behind cog or overshift onto crank arm.

Cable Tension. This is done by the barrell adjuster and ensures that the indexing corresponds between the lever and the mech so it moves the right amount for a given action by the lever.

pdw

As someone else has pointed out, when on the large front chainring, you can half press the downshift button, which should move the derailleur slightly inwards to avoid chain rub.

If you have a compact chainset, you may find that when on the small chainring, the chain rubs against the large chainring (not the derailleur) when using the smaller sprockets.

itsnotarace

smidsy wrote:

Actually a combination of both.

Well yes but if there is no rub when running a normal (straight) chain line then the likelihood is that the limit screws are adjusted correctly already

gmacz

Sounds like you are not using the gears properly. In both extremes it is noisy, you should not be in those gears. change the way you use the gears and then go in for the service.

olly64

ba68 wrote:

I have ultegra on my bike, 10 speed cassette and standard double chain set and can use the whole range with no rubbing so you (or you lbs) should be able to set it up to achieve the same Sorry if this is an obvious point but are you aware of the trim facility on the front mech?

Thanks ba68 I am aware that it can be trimmed and have played with it but not sure really what to do. When I drop onto the small front cog at first it seems to rub in which ever rear cog it is on and in playing with the trim I can calm it down.
I really do feel like a schoolboy learning every day. Many thanks for your post.

ba68

I didn't mean to be condescending when I mentioned the trim facility, so I hope you didn't take it that way. There are lots of articles on the web showing how to adjust the front mech and the Shimano docs are actually quite good, I would try and explain myself but that's easier to do if I am in front of a bike and it's cold outside at the moment! Look on line and take your time and with a bit of patience you should be able to sort it yourself and it's quite satisfying once you are able to do these things yourself, check Sheldon Brown or get hold of a copy of Zinn and the Art of Road Bike Maintenance both are really good sources of info. I agree with all the comments about cross chaining but there are times when it's easier and more convenient to do so and unless you run like that for a while it won't significantly increase wear, as for noise I don't notice any appreciable increase, yes it is slightly noisier but it doesn't bother me, perhaps that's an advantage of running a relatively high quality chain and crankset? By the way are you running a standard double, a compact or triple?

woodywmb

itsnotarace wrote:

smidsy wrote:

Actually a combination of both.

Well yes but if there is no rub when running a normal (straight) chain line then the likelihood is that the limit screws are adjusted correctly already

Correct. It's not the limit screws. Why would anyone want to ride in the biggest chainring and the biggest sprocket at the same time? This creates an inefficient chainline and puts the gearing under pressure.

Pross

Woodywmb wrote:

itsnotarace wrote:

smidsy wrote:

Actually a combination of both.

Well yes but if there is no rub when running a normal (straight) chain line then the likelihood is that the limit screws are adjusted correctly already

Correct. It's not the limit screws. Why would anyone want to ride in the biggest chainring and the biggest sprocket at the same time? This creates an inefficient chainline and puts the gearing under pressure.

Read again. He says the large chainring and 3 largest sprockets - that isn't normal and wipes out nearly half your gearing options! It won't be the limit screws doing that though as if the limits are slightly too tight it would surely only rub on the largest and / or smallest sprocket. More likely to be the angle of the front mech or the mech itself being bent.

itsnotarace

Pross wrote:

Read again. He says the large chainring and 3 largest sprockets - that isn't normal and wipes out nearly half your gearing options! It won't be the limit screws doing that though as if the limits are slightly too tight it would surely only rub on the largest and / or smallest sprocket. More likely to be the angle of the front mech or the mech itself being bent.

I interpreted it as meaning OP was cross chaining in both directions. When he writes "largest rear cog" he means 28, not 11

olly64 wrote:

On my first ride I felt the chain rub whilst on the largest front cog and the three largest rear cogs and also the reverse, smallest front cog and the four smallest rear cogs..

olly64

ba68 wrote:

I didn't mean to be condescending when I mentioned the trim facility, so I hope you didn't take it that way. There are lots of articles on the web showing how to adjust the front mech and the Shimano docs are actually quite good, I would try and explain myself but that's easier to do if I am in front of a bike and it's cold outside at the moment! Look on line and take your time and with a bit of patience you should be able to sort it yourself and it's quite satisfying once you are able to do these things yourself, check Sheldon Brown or get hold of a copy of Zinn and the Art of Road Bike Maintenance both are really good sources of info. I agree with all the comments about cross chaining but there are times when it's easier and more convenient to do so and unless you run like that for a while it won't significantly increase wear, as for noise I don't notice any appreciable increase, yes it is slightly noisier but it doesn't bother me, perhaps that's an advantage of running a relatively high quality chain and crankset? By the way are you running a standard double, a compact or triple?

Thanks for that ba68. I have looked at your trim suggestions and am going out to play with it and practice tomorrow night. I am getting the feeling that there isn't too much wrong with it all and just need to get used to using the gears in the right combinations and adjusting the front mech by trimming. Many thanks to everyone for your comments and suggestions.

Pross

itsnotarace wrote:

Pross wrote:

Read again. He says the large chainring and 3 largest sprockets - that isn't normal and wipes out nearly half your gearing options! It won't be the limit screws doing that though as if the limits are slightly too tight it would surely only rub on the largest and / or smallest sprocket. More likely to be the angle of the front mech or the mech itself being bent.

I interpreted it as meaning OP was cross chaining in both directions. When he writes "largest rear cog" he means 28, not 11

olly64 wrote:

On my first ride I felt the chain rub whilst on the largest front cog and the three largest rear cogs and also the reverse, smallest front cog and the four smallest rear cogs..

That last quote to me reads largest chainring and 3 largest sprockets e.g. 25, 22 and 19 with the 53 and also the 39 with 11, 12 and 13. Iwould expect issues and biggest / biggest and smallest / smallest but not on 3 in each direction.

velocanman

If you are really getting true chain rub (assumed on the front derailleur) in that many gears, the front der definitely needs to be adjusted. The technique is actually easier than it seems when you read the manuals. I have seen a number of videos on line that are incorrect or misleading.

Here are the basic steps:

- Shift the rear into the largest cog and smallest chain ring (this is the inner-most position of the chain).
- Remove the cable from the front derailler. (A LOT of instructions skip this step)
- Adjust the low limit screw on the front der until there is 1/2-1 mm between the chain and the front der cage.
- Screw the barrel nut at the shifter all the way down, then back out 1 turn. (Gives you more lengthening adjustment.)
- Reattach the cable to the front der.
- Shift the chain to the smallest rear cog and largest front chain ring (this is the outer-most position of the chain).
- Adjust the front der high limit screw so there is about 1/2-1 mm clearance between the chain and the cage.

That's it! These settings should set up the front der so it doesn't rub, and so it doesn't push your chain off the chain ring.