Decathlon 520 Cobra

[Jezd123]

Hi all,

Does anyone know anything about the Decathlon Cobra 520 please? I recently bought this one and would be interested to know how old it may be.

I’ve also posted in the mechanics forum as I’m looking for some new shifters for it. If you can help, it’d be very much appreciated.

Cheers!

 

[Cycleops]

I would assume that bike might have been part of Decathlons first range of bicycles and seeing as that didn't launch until 1986 and they started labeling the B'twin in 1999 it must be somewhere between the two dates. Looking at the style I'd say it was late eighties/early nineties but I may be wrong.
Is it a steel frame? What make/model is the rear mech? You might be able to date it a bit closer with those details and other components. If the saddle has a moulded base it will likely have a manufacturing date stamped in.

Nice bike.

 

[Jezd123]

I would assume that bike might have been part of Decathlons first range of bicycles and seeing as that didn't launch until 1986 and they started labeling the B'twin in 1999 it must be somewhere between the two dates. Looking at the style I'd say it was late eighties/early nineties but I may be wrong.
Is it a steel frame? What make/model is the rear mech? You might be able to date it a bit closer with those details and other components. If the saddle has a moulded base it will likely have a manufacturing date stamped in.

Nice bike.

Hi, thanks for your reply.

How might I tell if the frame is steel?

It says Shimano Acera X and on another part Shimano RSX. The shifters are Shimano RSX as well (currently broken and hunting new ones if anyone knows of anything suitable!).

The saddle does have a moulded base, but no date as far as I can see!

Interesting to hear about the dates of branding, thanks for that.

 

[biggs682]

@Jezd123 stick a magnet to it , steel will hold the magnet where as alloy will allow the magnet to move easily
rsx sti units are prone to the mechanicals to "gunk" up some times some new cable's and a good soaking in a wd40 / gt85 lubricant can help them come back to life
any similar speed sti units should swap over ie https://www.ebay.co.uk/itm/Shimano-...435695?hash=item25f3c30aaf:g:qyIAAOSwsaZa1ZPC or simply fit some down tube shifters

 

[SkipdiverJohn]

The unicrown forks are a bit of a clue as they appeared first on MTB's in the mid/ late 1980's then increasingly appeared on flat bar hybrids and then drop bar bikes from around 1990 or so onwards. My rough rule of thumb is a non-MTB frame will not be any older than 1990 if it has unicrown forks. I'd be very surprised if the OP's bike is made of anything other than plain hi-tensile steel.

 

[mikeymustard]

Shimano rsx 7 speed was early/mid 90's, they changed to 8 speed in about '99? Any shimano item should have a date code stamped on it [somewhere ].

rsx sti units are prone to the mechanicals to "gunk" up some times some new cable's and a good soaking in a wd40 / gt85 lubricant can help them come back to life
any similar speed sti units should swap over ie https://www.ebay.co.uk/itm/Shimano-...435695?hash=item25f3c30aaf:g:qyIAAOSwsaZa1ZPC or simply fit some down tube shifters

There's a video showing how to fix rsx shifters, you'll need the little tube thing that holds the spring in place to put them back together though! I have to say I've broken more than I've fixed thanks to being ham-fisted, so boat-loads of penetrating oil is maybe your best hope.
....And, thanks to them being a bit delicate, age-correct working examples tend to fetch silly prices on the bay, especially if it's your front shifter cos that looks like a triple and they are rarer than rocking horse sh1t!
I've used the microshift ones and they seem as good as the tourneys at least, and a little bit cheaper.
I've just found these too; no idea what they're like though, bit of a leap of faith

 

[Hardy]

Hi I have a 520 and it is cro moly frame not sure on year it's fitted with rsx all over also a cro moly saddle I wish to make this in to a touring bike, it comes with 700c 23c wheels I want to fit 30mm tyres

 

[SkipdiverJohn]

There's a lot more to it than fitting fatter tyres. Have a proper look at the geometry and the length of the rear chainstays before getting carried away. A tourer needs enough heel clearance so you don't strike any panniers whilst pedalling, and the geometry needs to be fairly relaxed and the wheelbase fairly long.

 

[Drago]

Im going with about 1998.

 

[Cycleops]

The deciding factor for the 30c tyres will be frame clearance @Hardy

Looks like the OP may have jumped ship.