DA 9170 + cross-chain in big ring : grinding noise??

Discuss light weight issues concerning road bikes & parts.
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Delorre
Posts: 891
Joined: Sat May 24, 2014 12:09 pm

by Delorre

I already asked in the 'cross chain' topic related to the latest DA, but did not get much reaction, so, I created of new topic specificly related to my 'issue. Did my fist ride on the new bike, DA 9170 equiped. 52/36 and 12-25 cassette. Have to say, shifting is absolutely spot on, even better than my other two 9070 bikes. But, and that bothers me somewhat, I have some issues when cross chain in the big ring. In the small ring, regarless of sproket used, eveything is silent, even at short +600w efforts, in or out of the saddle. Just perfect! In the big ring however, from the 19T and up (direction 25T), once let's say 400w, and especially out of the saddle, the chain makes a grinding noise at the back (a bit like you get during a rainy ride and the chains dries out). Eveyhing is new, I kept the factory lube on the chain, cassette it torqued down to spec, only the true axles where not as thight as it should ,I discoverd after the ride.

Any idea what causes this noice at high intensity? With moderate efforts, I don't hear anything, the chain seems to run smooth. On the bike stand, same, chain runs silently, even in 52/19 or 52/21. I'm a little torn between riding the bike as is and see if the thing disaprears with mileage due to chain- cassette "wear in" or to clean the chain already and lube with the usual Finish line and see if that solves the problem.

by Weenie


beeatnik
Posts: 322
Joined: Fri Jan 25, 2013 7:26 pm

by beeatnik

The hollow, wider chainrings.

JayUK
Posts: 44
Joined: Sat Jun 03, 2017 2:56 pm

by JayUK

Hi there,

When in the big chain ring, the only things that I could think of to cause the extra noise are:

1) The distance is less between the chain ring and the rear sprocket, therefore the horizontal angle for the chain will be larger, causing more rub on each link (this was an issue for disc based bikes where the chain stays had to be longer to accommodate the greater offset)

2) The small chain ring is more centred with the cassette, such that when you go in the large chain ring it is forcing the chain to have a larger horizontal angle to the rear larger cogs on the cassette (basically similar to the first point), thus causing more rub on the links.

This rubbing/friction is probably exasperated by the extra power/force being exerted on them.

This might be one reason why Shimano do not recommend cross chaining, their chains have a tighter tolerance on the pins/links and do not accommodate such a large horizontal angle, where as other makes don't seem to have an issue.

J.

deltree
Posts: 198
Joined: Mon Apr 23, 2012 10:21 pm
Location: London, UK

by deltree

Delorre wrote:Eveyhing is new, I kept the factory lube on the chain, cassette it torqued down to spec, only the true axles where not as thight as it should ,I discoverd after the ride.


My mechanic is always telling me the coating that chains come with from the factory is not lube but designed to prevent corrosion during storage/transport. Clean it off and apply a proper lube.

TobinHatesYou
Posts: 957
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

deltree wrote:
Delorre wrote:Eveyhing is new, I kept the factory lube on the chain, cassette it torqued down to spec, only the true axles where not as thight as it should ,I discoverd after the ride.


My mechanic is always telling me the coating that chains come with from the factory is not lube but designed to prevent corrosion during storage/transport. Clean it off and apply a proper lube.


While I agree that factory lube is too gummy, attracts dirt and bad for drivetrain efficiency, it’s definitely not causing the chain rasp.

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wheelbuilder
Posts: 400
Joined: Wed Feb 08, 2017 2:10 am

by wheelbuilder

B screw? Chain too short? Derailleur hanger bent?

Delorre
Posts: 891
Joined: Sat May 24, 2014 12:09 pm

by Delorre

wheelbuilder wrote:B screw? Chain too short? Derailleur hanger bent?


B-screw seems fine : no chain slap in the small-small, and a small, but sufficient distance between cogs and derailleur. Chain is a little too long, as the bike came with a 11-30 cassette, and I swapped to a 12-25 without shortening the chain. Visually, the rear mech is perfectly straight. Will check that later on if nothing else is found.

I torqued the TA's down to 10 NM. I have a ride foreseen this evening, will report back how it goes. It's really the only thing that comes into mind, I re-checked the whole setup as per the Shimano manual yesterday evening, from front mech to rear mech. I will fit a quick link and while at it, maybe remove 1 link from the chain. In the big-big, the rear mech cage is almost vertical to the ground, way too long IMO.

alcatraz
Posts: 730
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Check the upper derailleur pulley. It should be parallell with the cogs. Horisontally and verically. Check low and high speeds.

Maybe the hanger is slightly angled in favor of the small chainring.

If your chain tension is too high maybe you get some noise. Back off the B-screw a bit.

You might want to try a different brand chain to see which one works better to your liking.

/a

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ms6073
Posts: 2372
Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

Delorre wrote:Any idea what causes this noice at high intensity?

Chain line? Shift the chain into the 52 x 25 and then back pedal and check to see if the chain comes off the front chainring.
Michael - The Anaerobic Threshold is neither...

Delorre
Posts: 891
Joined: Sat May 24, 2014 12:09 pm

by Delorre

ms6073 wrote:
Delorre wrote:Any idea what causes this noice at high intensity?

Chain line? Shift the chain into the 52 x 25 and then back pedal and check to see if the chain comes off the front chainring.


Will do this evening, but chainline looks better in 52/21 than 36/15. Hello disc's and 410mm rear stays :wink:

Delorre
Posts: 891
Joined: Sat May 24, 2014 12:09 pm

by Delorre

Just an update. Bike has around 1000km's and for the last 500km's or so, no noice anymore up to the 3th last cog 8) I don't cross the chain more than needed, so haven't tried the last 2 cogs when in the big ring. It was probably a combination of need for wearing in and factory chain 'lube' I kept as long as possible.

BdaGhisallo
Posts: 1837
Joined: Wed Mar 17, 2004 1:38 pm

by BdaGhisallo

I have the same issue except with my 9070 drivetrain. I have it with DA 12-25 and 12-28 cassettes in combination with my 9000 SRM powermeter and an HG901 chain. My chainstays are 413mm so not exactly short. I have tried everything and can't figure it out.

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toiyuet
Posts: 167
Joined: Wed Dec 14, 2011 2:47 pm
Location: Hong Kong

by toiyuet

Delorre wrote:
Sat Jan 06, 2018 4:47 pm
Just an update. Bike has around 1000km's and for the last 500km's or so, no noice anymore up to the 3th last cog 8) I don't cross the chain more than needed, so haven't tried the last 2 cogs when in the big ring. It was probably a combination of need for wearing in and factory chain 'lube' I kept as long as possible.
Yes, 901 chain need mileage to break-in, than towards the end of life :(

by Weenie


Delorre
Posts: 891
Joined: Sat May 24, 2014 12:09 pm

by Delorre

toiyuet wrote:
Sun Jan 07, 2018 3:09 pm
Yes, 901 chain need mileage to break-in, than towards the end of life :(
My chains rarely see more than 3000 or 3500 km, so I don't worry about that :wink:

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