Embarrassing newbie question...

Clum84

Having just got my first road bike i'm trying to get my head round the gearing! Bike's a giant scr3 which has a triple chainring. think ive got the hang of shifting now but the probem i seem to have is that no matter what chain ring i'm in, i cant shift all the way up or down the cassette without the chain rubbing and grinding on the front mech at some point. for example if im in the bottom chainring and want to use the largest sprocket without the chain rubbing then this means if i shift to the smallest sprocket it starts to grind unless i then shift to the middle chainring. Hope that makes sense. Is this normal or do the gears need to be set up properly? i've tried adjusting the screws on the front mech a bit but i cant get it fully sorted and as ive never even touched a road shifter before this week im reluctant to have a bash fiddling myself.

advice as always is appreciated!

galaxyboy

This is a common problem on bikes with 9-10 rear gears and a front tripple. You should not try to use the extreme oposite gears ie front small - rear small, front large - rear large cogs as you will always get grinding on the front mech and it overstretches the chain. If the front mech is clear or just touching when in the middle cog on the front and large and small cogs on the rear then that is as good as you will get the setup.

Donut

I get exactly the same on my new Specialized Allez 27. I assumed that it was just one of those things I was going to have to get used to and just adjust the from mech slightly. I get it on the middle cog as well as the large/small ones
Donut

Clum84

i made a few adjustments of the screws and the hight of the front mech and I'd say that ive got it so that about 20 of the 24 gears are rattle free so i'm quite chuffed with my tuning skills thus far!

Just had the bike out for it's first proper ride today and i reckon i only used about 4 or 5 gears so i guess it isnt going to be much of a problem. Will see how many i need when i hit the alps next week though!

cheers for the replies.

merlin321

Identical problem with my new SCR2. After some excellent responses from this forum I found the best/quietest way to use the gears was:
Smallest front ring - only use rear gears 1 through 5 (or 6 at a push)
Middle front ring - use all 9
Largest front ring - only use rear gears 5 through 9.

This worked best for me and meant there was no adjustment needed on anything. Just practise.

Hope this helps.

Nick6891

i always get all the gears set up for the middle cog and only use lower one for up hills and upper one for downhills or fast straights

david 142

Generally speaking you shouldnt expect to be able to use all the sprockets with any one chainring. If its going to work out it will be with the middle ring, simply because its more centrally aligned, but even though the chain might not be rubbing on the front cage its not good practice because the chain is being bent sideways unneccessarily, increasing wear and tear.
The basic idea is to use the little ring with the bigger sprockets...and so on, as I'm sure you know
What you might not have realised is just how many gear ratios are duplicated, or nearly duplicated, using the commonly available selections of chain rings and sprockets.
If you bung the details of your bike into this: http://sheldonbrown.com/gears/index.html it will generate a handy little chart that will show you, among other things, where duplication exists. You can then decide which sprockets to use with which ring, remembering that a straight chainline is to be preferred.

PS If in the UK select "Gear inches" to make sure that you get numbers that others will be able to understand! If you want to read more about gearing just use some of the links at the bottom of the page. HTH

Felix-da-house-mouse

i get it on my DOUBLE!!!! small ring on the and 1,2,3, on the back and then the same with 10 the on big front i get it on 9,10. how do i fix it? i'm worried about adjusting the cable at the back with the black nut like bit on the cable incase i totally balls it up.

Bugly

YOU SHOULD Not RIDE on the extreme gears - it wears out the chain and the cogs. For your triple you should restrict yourself to

inside chainwheel (small) the 6 or 7 inner most cogs, middle chain ring the middle six to 8 avoinding the extremes a nd in the outside large chainwheel you should be using the outer 6 or seven cogs. DO NOT TRY TO STOP RUBBING on the front derailuer by 'adjusting' the set screws unless you are getting rubbing in the inner chainring and inner gear on the cluster or the outer chainring and the outer gear.

If you are getting rubbing in other comibinations its a matter of feathering the front derailuer on your shift lever. ie small movement on the lever one click will move the deraileur engouh to stop chain rub,

If you have a click on the rear gear its most likely you need to adjust the cable tension at a barrell adjuster until the clicking stops.

Badly set set screws result in dropped chains or worse chains jammed in between cluster and wheel causing spoke damage.

If you dont know what you are doing read Park tools how to guides to get you started. Blindly fiddling leads to damaged components or rider,

Bugly

Felix-da-house-mouse

if you dont use these gears then your losing a massive percentage of the gears the easiest for hill climbing and the hardest for full blown crazyness. lol

Bugly

:shock:

Felix if you are refering to my post either I suggest you misread what was said.

david 142

Felix-da-house-mouse wrote:

i get it on my DOUBLE!!!! small ring on the and 1,2,3, on the back and then the same with 10 the on big front i get it on 9,10. how do i fix it? i'm worried about adjusting the cable at the back with the black nut like bit on the cable incase i totally balls it up.

Its not clear, to me at least, what your problem is.
When you say "the cable at the back" do you mean the cable to the rear mech or the back end of the front cable?
Is your chain rubbing on the front mech in these gears, or is the chain not engaging properly on the rear sprockets?

salsarider79

Some front mechs have a 'trim' option. When in the big ring you do sometimes get a small amount of rubbing, however some front mechs have a small downshift, just before it drops on the small cog at the front. You shouldn't really need it, because as some people have said, it wears out componants. It's true that some ratios are repeated, but sometimes its easier to accept a bit of rubbing, than to try to find a similar ratio elsewhere in the gear range. Remember: you are riding your bike, so do as you feel comfortable.
p.s. could always go singlespeed....

unclemalc

http://sheldonbrown.com/derailer-adjustment.html#