Dura Ace 7900 rear mech - jockey wheel

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Farrina
Posts: 118
Joined: 26 Nov 2012, 8:15pm

Dura Ace 7900 rear mech - jockey wheel

Post by Farrina »

Learned Bretheren,

Much to my surprise (is it just me or do modern components seems to wear out faster these days ?) the jockey wheels on my 7900 rear mech appear to be shrinking at an alarming rate.

Poking around on the Shimano website suggests I need a "tension and guide pulley set" (ref Y5X098140) but I am struggling to locate a retailer of the same.

Does anyone know where I might purchase them (or recommend a comparable product - I am not particularly bothered what I fit as long as it's fully functional.

Many thanks

Alan
Brucey
Posts: 44516
Joined: 4 Jan 2012, 6:25pm

Re: Dura Ace 7900 rear mech - jockey wheel

Post by Brucey »

this

http://bike.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/RD/EV-RD-7900-2871A_v1_m56577569830676546.pdf

says that you need these

https://www.sjscycles.co.uk/gear-spares/shimano-duraace-rd7900-tension-guide-pulley-unit-y5x098090/

-which have recently become 1/3 more expensive for no readily apparent reason..... :roll:

BTW if the pulleys are wearing rapidly on the outside, this is accelerated by bad alignment, mucho dirt, draggy pulley bearings, and/or a worn chain.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Farrina
Posts: 118
Joined: 26 Nov 2012, 8:15pm

Re: Dura Ace 7900 rear mech - jockey wheel

Post by Farrina »

Brucey,

Thanks for the super swift response.

Not sure where I got that Shimano part number from, as I was looking at the same tech document as you.

I have managed to locate a set via Amazon for £29.99 (which I presume was their normal price before inflation/devaluation struck).

Cheers

Alan
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Gattonero
Posts: 3730
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Location: London

Re: Dura Ace 7900 rear mech - jockey wheel

Post by Gattonero »

Tacx jockey wheels do work very well too. They are multi-fit so an easy choice.
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...
Farrina
Posts: 118
Joined: 26 Nov 2012, 8:15pm

farrina

Post by Farrina »

Thought I would add an update to advise that my order for the Dura Ace jockey wheels (at an expensive £30 pair) fell through :-(

The only other alternative sources have increaed in price to a truly eye watering £40 (you would think they were gold plated at this price!)

I took Gattonero's advise and sourced a pair of Tacx jockey wheels for £10 that seem to work very well.

Given that I am over 13 stone I feel I can accomodate the extra 2 grams of the Tacx (and the £30 sitting in my pocket, rather than Shimano's)

Cheers

Alan
fastpedaller
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Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Dura Ace 7900 rear mech - jockey wheel

Post by fastpedaller »

Having used Tacx I'm of the opinion that the ball bearings aren't particularly well sealed, and plain bearings last longer - what is the experience of others?
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Gattonero
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Joined: 31 Jan 2016, 1:35pm
Location: London

Re: Dura Ace 7900 rear mech - jockey wheel

Post by Gattonero »

Most of the big brands would use plain bushings, with the exception of Sram and Campagnolo/Shimano on their top-tier do use a good quality of cartridge bearings.
The Tacx jockey wheels do use a bearing with decent size balls, and isn't too complicated to lift the rubber seal and flush+repack, as the bearings have a cage that does leave some space in between.
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...
Brucey
Posts: 44516
Joined: 4 Jan 2012, 6:25pm

Re: Dura Ace 7900 rear mech - jockey wheel

Post by Brucey »

fastpedaller wrote:Having used Tacx I'm of the opinion that the ball bearings aren't particularly well sealed, and plain bearings last longer - what is the experience of others?


yup, the seals are pretty basic, and once the water gets in, it tends to stay in. The XT/ultegra lower pulleys which have cartridge bearings in have better seals plus shields over the top. They are also expensive for what they are but they do last pretty well.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
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Gattonero
Posts: 3730
Joined: 31 Jan 2016, 1:35pm
Location: London

Re: Dura Ace 7900 rear mech - jockey wheel

Post by Gattonero »

The shield on the Shimano jockey wheels is just a cover that does not help keeping the moisture out. May keep the coarse stuff, but the road spray will seep in, and will also stay in. Some models will have a lip seal around, that does a better job though is not perfect.
As far as the cartridge bearing type, they both use a rubber seal, and to be fair you may even replace the Tacx bearings as they are a known size (#607):
https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1
I doubt that the bearings in Shimano jockey wheels would last twice as long, since they are a lot more expensive.
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...
Brucey
Posts: 44516
Joined: 4 Jan 2012, 6:25pm

Re: Dura Ace 7900 rear mech - jockey wheel

Post by Brucey »

Fastpedaller has a point in that some folk do get the cheapest pulleys to last well. However I think that it does take some effort to do this, unless you never ride in mucky conditions. The two usual problems are lack of lube and dirt in the bushings. If you strip, clean and relube the pulleys once every few hundred miles they can last well, but this is not something that everyone is prepared to do.

If you want cheap jockey pulleys (i.e with basic shields and plain bushings) that can last well with least net effort, consider doing what was done to the jockey pulleys in the 'supercommuter' thread; these (and the mounting bolts) were modified to include a grease port. Once this is fitted, the pulley bushings can be purged/relubed in a few seconds. Any crud in the bushing is carried out by the excess lube. If this is done at intervals (e.g. whenever the chain is lubed), the pulley bushings can last almost indefinitely.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
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