Gadget on rear chain stay of TdF bikes

[zacklaws]

Anyone any idea what the "thing" is on the left hand rear chain stay is that pokes downwards about an inch or two, some bikes have them some don't, but when you spot them they stand out a mile? I initially thought it was for cadence, but after seeing some close ups of a rear chain stay yesterday with the item fitted, I also saw a bit further up the chain stay towards the BB is what looks more like a cadence sensor fitted on the top side of the chain stay as well.

Wireless cycle computer working off back wheel?

 

[maurice]

Anyone any idea what the "thing" is on the left hand rear chain stay is that pokes downwards about an inch or two, some bikes have them some don't, but when you spot them they stand out a mile? I initially thought it was for cadence, but after seeing some close ups of a rear chain stay yesterday with the item fitted, I also saw a bit further up the chain stay towards the BB is what looks more like a cadence sensor fitted on the top side of the chain stay as well.

Wireless cycle computer working off back wheel?

Shouldn't need a very big sensor for a normal bike computer, I was thinking the Polar CS600 power meter when I first read this, but that goes on the right hand chain stay, i.e.

.

 

[zacklaws]

I find it annoying that searching through all the photo's on line, I cannot find one with the item fitted, but I have suspicions it could have something regarding power meters. even more so seeing that polar one which measures vibrations from the chain, but as you say it is on the wrong side.

 

[Smokin Joe]

Timing transponders.

 

[Stephen-D]

I have seen it to and just thought it was there timing chip!

 

[buggi]

is it something to do with this new electronic gear change?

 

[Smokin Joe]

is it something to do with this new electronic gear change?

No.

 

[HLaB]

Or could it be a GPS tracker ?

 

[Crackle]

Timing transponders.

That's what I thought. They're on every bike and are exactly the same, same place as well.

 

[Deleted member 1258]

Some info here

http://www.purdy.org.uk/pfinish/transponders.htm

 

[scott s10]

its an cadence gadget (measures yur cadence)

 

[Smokin Joe]

its an cadence gadget (measures yur cadence)

No, it's a timing transponder.

 

[zacklaws]

Timing transponders.

That's what I thought. They're on every bike and are exactly the same, same place as well.

Unless things have changed, not all bikes do have them unless they have them mounted in a more discreet place, but those that do, have them at some point along the chain stay.

 

[Deleted member 1258]

See the link on my post at the bottom of page one.

 

[Chrisc]

definitely a timing transponder