Advice sought - Noisy Shimano Sora groupset

[JonnyRat]

Dear All, I've been riding a Bianchi Via Nirone with 18 speed Shimano Sora groupset for only 8 weeks now. The bike has had a 4 week 'service' to re-calibrate cables / gears etc. However I notice that it's quite noisy when I select the large front cog and any of he 3 larger cogs on the rear cassette. My LBS suggests that this is normal. I appreciate that Sora is on the 'lower end' of the Shimano groupset (budget & performance wise) and that chain angle can adversely the gearing on the extreme high / low gears, but surely an 8 week old bike should still be relatively 'noise free'. I tend to ride 100 miles per week (approx) so this noise gets quite irksome after a while (I think the noise comes from the chain rattling against the front derailleur - but am not 100% positive).

Any advice you can offer would be gratefully received. Other than the above, the bike is superb and I love it!

 

[Smokin Joe]

Chain rub on the front mech is the most likely cause. Campag front shifters have a trim function so you can nudge the mech in a bit to avoid contact, not sure if Shimano do especially on the lower end kit. Once you get used to the gears you will find you have plenty of ratios available on both chainrings to avoid running the chain across the cassette. Download a gear chart (loads available) and you will find combinations of small ring/sprockets that are so close to what the big ring and big sprockets give you that the difference won't matter.

Assuming your LBS is Mike's Bikes they are very good and know what they are talking about.

 

[rockyraccoon]

... However I notice that it's quite noisy when I select the large front cog and any of he 3 larger cogs on the rear cassette...

Yes that is normal and you should avoid those combinations. They'll increase chain and cassette wear.

What happens is when you use the largest chainring and the largest sprocket a lot of noise generated due to the chain rubbing the front mech. That is known as "cross-chaining" (using the smallest rear cog with the smallest front ring, or the largest rear cog and the largest front ring)

Bicycle chains are quite flexible, and will work fine with any combination. Even knowing they are there available to be used and can work ok, these combination should be avoided.

 

[rockyraccoon]

...
Download a gear chart (loads available) and you will find combinations of small ring/sprockets that are so close to what the big ring and big sprockets give you that the difference won't matter.
...

Gear Calculator

 

[JonnyRat]

Joe & Rocky,
Many thanks for the really helpful responses. Have consulted the Sora instructions on 'trimming' as you call it Joe and this can be undertaken on Sora. Just tried it out and made a a niticeable difference, so thanks very much. Rocky - thanks for taking the trouble to attach the gearing charts - have saved these for future reference. You're quite correct - time & more mileage will teach me to become more comfortable with the gear combinations.
Oh, the LBS wasn't Mike's Bike's - I totally agree, they are always helpful and really 'clued-up' whenever I've had occasion to consult them. Won't name the LBS on this forum - would not be fair as it was probably my incompetence (not theirs) which lead to my original query!!
Thanks again.

 

[alecstilleyedye]

This topic has been moved to Know How by the admin team.

 

[chugsy]

My left/front shifter is for a triple even though I only have two chainrings - the third position can be used as a trim for the highest of gears to avoid chain rub. Pushing the downshift takes a lot more effort than a normal press though... so much so I thought it was broken when I rode the bike home from the shop so had to double back to Evans Cycles up hill in high gears :'( ...... only to be told there was nothing wrong!

 

[JonnyRat]

My left/front shifter is for a triple even though I only have two chainrings - the third position can be used as a trim for the highest of gears to avoid chain rub. Pushing the downshift takes a lot more effort than a normal press though... so much so I thought it was broken when I rode the bike home from the shop so had to double back to Evans Cycles up hill in high gears :'( ...... only to be told there was nothing wrong!

Thanks Chugsy - know what you mean about effort required on the downshift. Getting the hang of it now though.

 

[HLaB]

Yes that is normal and you should avoid those combinations. They'll increase chain and cassette wear.

What happens is when you use the largest chainring and the largest sprocket a lot of noise generated due to the chain rubbing the front mech. That is known as "cross-chaining" (using the smallest rear cog with the smallest front ring, or the largest rear cog and the largest front ring)

Bicycle chains are quite flexible, and will work fine with any combination. Even knowing they are there available to be used and can work ok, these combination should be avoided.

I don't get much rub, when I've shifted by mistake to Big/Big but I do get it in the small/small and its an audible warning to get out of the gear

 

[JonnyRat]

Thanks HLAB - am learning all the time from this forum. Really appreciate your opinions.

I don't get much rub when I've shifted by mistake to Big/Big but I do get it in the small/small and its an audible warning to get out of the gear