drivetrain noise
Discussion
I've just purchased a new road bike (Specialized Allez with Tiagra groupset) and have been out a handful of times on it doing no more than 75 miles in total. It has two chainrings up front and ten sprockets at the rear. When I'm on the large front chainring, the drivetrain gets noisy if I go onto any of the 4 largest sprockets at the rear, and vice versa when I'm on the small front chainring. So it means that I only really have 6 rear sprockets that are usable at any time.
Is this normal or does it need some adjustment, or is it just a case of it running in?
On my old hybrid with 3 front chainrings and 7 sprockets at the rear, I could probably use 5 or 6 of the rear sprockets at any time.
Is this normal or does it need some adjustment, or is it just a case of it running in?
On my old hybrid with 3 front chainrings and 7 sprockets at the rear, I could probably use 5 or 6 of the rear sprockets at any time.
What do you mean by "noisy"? Check that the chain isn't fouling on the front mech, I'll bet that's the issue given your description. There is a good "how to" guide on the park tool website but its pretty simple on a double chainset. Just adjust the H and L screws till it runs free
Factory lube is alo notoriously sticky so that could also be a factor, it's good stuff though so don't think of cleaning it!
Factory lube is alo notoriously sticky so that could also be a factor, it's good stuff though so don't think of cleaning it!
rpm1969 said:
I've just purchased a new road bike (Specialized Allez with Tiagra groupset) and have been out a handful of times on it doing no more than 75 miles in total. It has two chainrings up front and ten sprockets at the rear. When I'm on the large front chainring, the drivetrain gets noisy if I go onto any of the 4 largest sprockets at the rear, and vice versa when I'm on the small front chainring. So it means that I only really have 6 rear sprockets that are usable at any time.
Is this normal or does it need some adjustment, or is it just a case of it running in?
On my old hybrid with 3 front chainrings and 7 sprockets at the rear, I could probably use 5 or 6 of the rear sprockets at any time.
You're worrying over nothing. What you've described (front: big, rear: big, and vice versa) is referred to by some as "cross chaining": running the chain at the most extreme angle front:rear. It's not...ideal...but they can still take it. Most of the noise will be coming from the front mech, with the chain rubbing against the shifting cage. You should be able to "trim" this out using the shifter for the front mech: you should feel two "clicks", I believe when shifting down (the first seemingly does nothing, the second then changes down to the smaller chainring). The first "click" moves the front mech onwards by a couple of mm, to move the inner plate away from the chain when at such extreme angles, and reduce/prevent rubbing and the noise.Is this normal or does it need some adjustment, or is it just a case of it running in?
On my old hybrid with 3 front chainrings and 7 sprockets at the rear, I could probably use 5 or 6 of the rear sprockets at any time.
rpm1969 said:
Thanks. I think it probably is the chain rubbing against the front mech. I'll try trimming it as you suggest and if that doesn't work then look at adjusting it.
Don't expect to eliminate it completely, its not expected for you to ride it with a big angle on the chain - aside from the fact you'll be in a likely duplicated gear, riding with the chain at an angle like / will shorten the life of the chain considerably. I would expect it to still foul on the biggest 2 at the rear at least.
This ^^
There's overlap between the gears (by design); therefore there is *no need* to be in the smallest at the back and front at the same time, or vice versa - change to the big ring before you get there, and move back in on the cassette. 2 smallest will be a 'longer' gear than the two biggest.
It does sound like some adjustment may be needed however.
There's overlap between the gears (by design); therefore there is *no need* to be in the smallest at the back and front at the same time, or vice versa - change to the big ring before you get there, and move back in on the cassette. 2 smallest will be a 'longer' gear than the two biggest.
It does sound like some adjustment may be needed however.
There is much published wisdom on the internet regarding this issue. Among the gurus who dispense their knowledge freely is Sheldon Brown. Here is a link to the full article on his site... http://sheldonbrown.com/gear-theory.html
Please use the link. There is much that can be learned from Sheldon Brown's site. Some of the text which is most relevant to your described problem, I have taken the liberty of reproducing below:
Chainline and Criss-Cross Gears
A chain drive is one of the most efficient mechanical linkages there is. This is true as long as the chain runs in a straight line, but derailer gears don't always run the chain in a straight line. As you select gears that run the chain at an angle, the efficiency drops somewhat as the angle increases. For this reason, you should favor combinations that allow the chain to run nearly straight.
Generally, the large outer chainring shouldn't be used with the largest rear sprocket, because of the sharp angle it creates.
Similarly, the small inner chainring shouldn't be used with any of the smaller rear sprockets.
The small-small combinations create extra problems besides the bad angle. The smaller the front chainring, the greater the pull on the chain; the smaller rear sprockets only engage a very few teeth with a very few chain rollers at any one time, so stresses are concentrated. If you make a habit of abusing the small chainring of a triple crank by using it with the smaller rear sprockets, you will drastically increase the wear rate of both chain and sprockets.
Duplicate Gears
Sometimes cyclists get hung up on the idea that it is important in selecting sprocket sizes to find a combination of cluster and chainwheels that avoids duplication, so that every combination of front/rear sprocket gives a distinct and unique ratio.
This may have made sense back in the days of 4 and 5 speed clusters , but with modern gear systems, it is of no practical consequence. Indeed, having a few gears duplicated can often help to simplify the shifting pattern!
When you do encounter duplicate gears, in almost all cases, one of the combinations will involve running the chain at an extreme angle, so you should generally use the other one. The fact that the bad-angle gear is a duplicate doesn't matter, because you shouldn't be using it anyway.
Please use the link. There is much that can be learned from Sheldon Brown's site. Some of the text which is most relevant to your described problem, I have taken the liberty of reproducing below:
Chainline and Criss-Cross Gears
A chain drive is one of the most efficient mechanical linkages there is. This is true as long as the chain runs in a straight line, but derailer gears don't always run the chain in a straight line. As you select gears that run the chain at an angle, the efficiency drops somewhat as the angle increases. For this reason, you should favor combinations that allow the chain to run nearly straight.
Generally, the large outer chainring shouldn't be used with the largest rear sprocket, because of the sharp angle it creates.
Similarly, the small inner chainring shouldn't be used with any of the smaller rear sprockets.
The small-small combinations create extra problems besides the bad angle. The smaller the front chainring, the greater the pull on the chain; the smaller rear sprockets only engage a very few teeth with a very few chain rollers at any one time, so stresses are concentrated. If you make a habit of abusing the small chainring of a triple crank by using it with the smaller rear sprockets, you will drastically increase the wear rate of both chain and sprockets.
Duplicate Gears
Sometimes cyclists get hung up on the idea that it is important in selecting sprocket sizes to find a combination of cluster and chainwheels that avoids duplication, so that every combination of front/rear sprocket gives a distinct and unique ratio.
This may have made sense back in the days of 4 and 5 speed clusters , but with modern gear systems, it is of no practical consequence. Indeed, having a few gears duplicated can often help to simplify the shifting pattern!
When you do encounter duplicate gears, in almost all cases, one of the combinations will involve running the chain at an extreme angle, so you should generally use the other one. The fact that the bad-angle gear is a duplicate doesn't matter, because you shouldn't be using it anyway.
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