Gearing problem

Trekboy

New Member
I have just brought a racing bike and have found when the chain is on the the biggest cog if I select the lowest or highest gears I get a bad grating noise. The man in the shop said its because the chain is not straight when using these gears on the biggest cog and it should not be used. If I want to use the first and last gears then I should select the smaller cog. Is this correct please?
 

colinr

Well-Known Member
Location
Norwich
Your highest gear should be biggest cog on the front and smallest on the back. Lowest is smallest on the front, biggest on the back.

If you're going biggest to biggest / smallest to smallest then it makes your chainline really bad, the shop man speaks the truth.

You can half-change the gear (trimming) to move the chain guide as a stop-gap but you want to change gear really.
 

Paulus

Started young, and still going.
Location
Barnet,
colinr said:
Your highest gear should be biggest cog on the front and smallest on the back. Lowest is smallest on the front, biggest on the back.

If you're going biggest to biggest / smallest to smallest then it makes your chainline really bad, the shop man speaks the truth.

You can half-change the gear (trimming) to move the chain guide as a stop-gap but you want to change gear really.
+1 The grating noise you can hear is probably the chain rubbing on the front derailer as the chain is at an acute angle across the gearing. Try not to use the largest chainring (front) and the largest sprocket at the back. If you have a triple chainset the same goes for the smallest chainring and the smallest sprocket.
 
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