You can download a sheet with various torque specifikations on SRM's homepage here: http://www.srm.de/gb/support/phoca-down-test/category/28-mounting?download=96%3Asrm-torque-specifications

good news no wires attached to torque disc and the gossamer has 2 LTC-7PN -S4 bateries

the torque disc was very easy to take off and just as easy to put back.

Batteries are arriving tomorrow will take photos and post here.

any tips on soldering have been practising but the batteries are tiny

wow that was easy took less than five minutes including taking crank of the bike, cleaning, removing cover, touch solder iron to wire falls off, add little solder to iron, touch wires to new battery and solder repeat


my SRM is working. anyone can do this I plan on getting some spare batteries as my ones only lasted a year. But basically there is no need to send it of to Germany and have no data for at least a month plus it only cost $35. The wireless SRM is much easier as there is no wires attached to the cover so you don't need to remove the axle.

thanks for all the help

just replaced the battery my canondale hollowgram si srm - no problems! I got the battery from the local distributor of the Gemini Tinytag - what a great tip that was by 2wheels.


just curious - does anyone know what the copper wire that is wound around inside the white cover is for?

I'm a big chicken when it comes to messing around with electrical anything, but I may try this on one of my older SRMs when the next battery goes. Thanks for the encouraging posts!

to add to the list, the sram s975 srm can be done the same way

make a note of cover orientation so you can refit with the dot at the same place

remove small chainring, this reveals a small indent on each arm of the spider, you can get a pick in here to pop off the cover, there are no wires to the cover

takes two of the rectangular LTC-7PN -S4 cells

the cover needs to be firmly pressed back in place around both inner and outer edges

Here's the inside of my custom wireless Campy BB style SRM. Nearly identical to the pic of the SRM that Coloclimber showed earlier in this thread, except that mine had 16 strain gauges, 4 on each of the 4 "arms". There are 2 on the top and one on each side.

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Have you ever wondered if there was more to life, other than being really, really, ridiculously good looking?

Can somebody please put my mind to rest. I have a 7900 DA SRM and removed the black plastic cover. I have it back on but there is some play on the inside near where the torx bolts attach it to the crank. IS this normal? I've taken this thing on and off now well over a dozen times and no matter what I do it is always there. It is about a millimeters worth of movement and feels like it is the seal compressing. Can anyone check theres and tell me if this is normal or not??

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Do you dare to dream?????

No. That is not normal. I don't know exactly what Uli has done to the new 7900 SRM, but my friend (who was the long-time Canadian distrubutor for SRM and spent several years working with Uli in Germany) will not touch the DA PowerMeter now. If he won't open it, it really makes me concerned about doing it.

Insert naughty word *HERE*

After my panic - I restripped cleaned the seals and just used a new one on the inside as the old one had stretched to all buggery and now viola no play!

Edited to add though my crank still sounds like a WW1 tank when climbing and a old girl knitting when sitting. Not sure how much longer I can tollerate it! I've stripped and regreased everything that can be taken apart here folks - any suggestions??

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Do you dare to dream?????

Hi all, first time poster with particular interest in this topic.

I bought a wireless DA SRM from the states (live in Oz) in May 2008. It has the black and white decal scheme on the front. Apparently the wireless DA units (with ANT) were meant to be good for approx 1400 hours of use. I used mine for about one year before being hit by a car and not having that bike for over a year. Note the SRM worked fine after that incident. Anyway I would not have used the unit for more than about 300 hrs up until that point. Using it recently it would not give any readouts to the Garmin head unit. Figured battery was flat and after seeing how much it would cost to ship to either NZ or Germany (insured etc) I found this thread about doing it myself. Apparently I should have the round 3.6v electrochem type battery.

Upon opening it up I have found that it has a single, rectangular 3.5v keeper 750mAH battery (LTC-7PN-S4). Similar to the Specialized units. Conspiracy theories are now entering my head...

This single battery might help explain why I got such reduced life in the unit (they quote 750 hrs - still more than I got)

Did I get ripped off in terms of paying for a unit that needs battery replacement more often than that quoted? Or could it be possible that the circuitry inside is not to the same quality as what it should be (less strain gauges etc)?

Also, I did notice a small amount of fluid adjacent to the battery. Not sure if this is some form of lubricant or signs of a leaking battery or moisture ingress. ANy thoughts on this would be appreciated.

Thanks in advance.
Mike

I think you got your hands on one of the first wireless models: I think they had only one battery to start with. The battery inside the Powermeter will loose current with time - also when it is left unused for a long time.

Regarding mosture - I had a wired SRM some years ago that worked fine - but when opening it for a batterychange it actually had some water inside. The guy that helped med with the batterychange had it open for a day and made sure it was thoroughly dried before making a batterychange, and sealing the unit again. It worked fine afterwards... He told me it was a good idea to give the seal some silicone-grease to make sure the powermeter stays watertight... Of course water is not good for the unit: But SRM's are quite wear resistant in my opinion.

On the other hand - SRM Germany once "forgot" to install the seal when they serviced an SRM for me years ago... One ride in the rain and and I could actually HEAR the water splashing around inside the cranks. THAT killed the powermeter Fortunately SRM gave me a new powermeter so everything went well after all

Dura ace SRM's have ONLY been made with 8 strain gauges: so no need to worry (or calling the FBI ).

Thanks for the reply Lars. Guess I'll just accept that I'll need to replace the battery a little earlier than expected. So long as I can do it myself though I don't mind.

Now I shall look for an Oz retailer for the Keeper battery!

Long shot...

Is there anyone in the SF Bay Area who has a good track record of doing this? The battery in my DA wired system (PowerControl V era) died, and I can't afford the $ and the time off the bike (no spare crank) to get it serviced by SRM. So... it's kind of an expensive ride timer at the moment. Though it also shows ambient temp, too... .

If you want to drive to Benicia after work during the week I will help you change it.

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Have you ever wondered if there was more to life, other than being really, really, ridiculously good looking?