SRM 9000 Chainring Bolt Torque

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ddj5300
Posts: 42
Joined: Sat Jan 08, 2011 1:51 am

by ddj5300

Hello,

I have recently changed the chainrings on my SRM 9000 & I was wondering what the torque setting should be for the SRM 9000. Shimano states that the chainring torque should be 12-16nm, and SRM has not updated their torque setting sheet to include the 9000 crank.
Currently I torqued the bolts to 13nm (within Shimano specs), but I am worried that that will change my slope value.

I also have an offset number of 2100 - I have heard it said before that the number should be lower than that - can anyone confirm or deny that?

Thanks

djm
Posts: 1403
Joined: Thu May 14, 2009 12:19 pm
Location: Norway

by djm

I'm running with 12nm out of old habit from my 7800 SRM. Seems to work very well. The bolts were covered in a bit of Loctite from SRM I believe. I was planning to swap rings on it during my Benidorm training camp (some really heavy rides) and broke the tool I had brought along, thanks to the Loctite making removal require a whole hell of a lot more than 12nm to unscrew them.. not reapplying any Loctite myself :-)

Once torqued sufficiently, I do not believe over-torquing the bolts will affect slope. Maybe someone more knowledgeable could chime in on that.

On the Garmin I have an offset around 690-715 depending on temperature (0-27 degrees Celsius so far). I believe this is a normal offset.

I have been having some difficulties lately with the Garmin. All of a sudden the automatic function in it sets the offset to some wild number (1000-2000). The connection with the SRM remains intact, but there is no cadence or power reported. I had this problem earlier with my old SRM and older firmware on the 800. Hopefully cleaning it of old fit-files and resetting it has helped, the problem has not occurred since.

by Weenie


ddj5300
Posts: 42
Joined: Sat Jan 08, 2011 1:51 am

by ddj5300

Thanks for the response djm - I have an email in to SRM and will post their response.

ddj5300
Posts: 42
Joined: Sat Jan 08, 2011 1:51 am

by ddj5300

Talked to SRM in Colorado. The chainring bolt torque they use is 11NM and they use blue loctite. I also asked about my high zero offset 2100 and they said as long as it is stable that it is ok - and it does give predictable power.

WeightySteve
Posts: 293
Joined: Wed Jun 09, 2010 10:44 am

by WeightySteve

I've owned 4 SRM's - 2 Wired, 2 Wireless (but admittedly 7800's and 7900's, never had a 9000). All of them have had zero offset around 550 (give or take 20Hz), so I would be concerned about one as high as yours.

From SRM's FAQ: http://www.srm.de/support/faq/powermeter/

My zero offset is too low (below 200Hz), too high (above 900Hz), or reading Zero. What is the cause?

Your PowerMeter may have sustained damaged that is beyond the scope of troubleshooting.
Your PowerMeter battery is low/nearly depleted.
Its advised you contact your local SRM Service location for a more detailed diagnosis of your technical problem.


Do you check the zero offset regularly during a ride? (and before setting off?). Has it always been so high since you've owned it?

But yes, if it's stable the head-unit will calculate the correct wattage.

Maybe 9000's are newer than that FAQ, and their updated electronics naturally generate higher Hz at zero torque.

goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

Nope. Rider here has the 9000, and his offset is a stable 495

BdaGhisallo
Posts: 1852
Joined: Wed Mar 17, 2004 1:38 pm

by BdaGhisallo

Me too. My 9000 PM zero offset hovers around 586-588 within a temp range of 55F to 75F.

ddj5300
Posts: 42
Joined: Sat Jan 08, 2011 1:51 am

by ddj5300

The zero offset has always been high on that power meter (purchased new one of the first 9000 models), but the data I get from is seems to be consistent with my other power meters - when compared to perceived exertion & heart rate. Seems weird that I received it with a high zero offset though.

ddj5300
Posts: 42
Joined: Sat Jan 08, 2011 1:51 am

by ddj5300

My zero offset is too low (below 200Hz), too high (above 900Hz), or reading Zero. What is the cause?
A
Your PowerMeter may have sustained damaged that is beyond the scope of troubleshooting.
Your PowerMeter battery is low/nearly depleted.
Its advised you contact your local SRM Service location for a more detailed diagnosis of your technical problem.

-I don't think i have damaged my power meter
-The battery still shows just over 2000 hours on it
- I did contact SRM and they told me it is fine if it is stable

Still makes me think there is something wrong since the zero offset has always been high since,

goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

Don't worry......its the gold standard.

by Weenie


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