Shimano 105 Chainring - Alloy specification ?

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Jules59
Posts: 2
Joined: 16 Jan 2019, 2:34pm

Shimano 105 Chainring - Alloy specification ?

Postby Jules59 » 16 Jan 2019, 2:47pm

Hi
My first post on here.

Does anyone know which aluminium alloy Shimano uses for its 105 Chainring FC5750 50T? Ive searched on the internet but I cant find that information - the Shimano websites are not forthcoming.
Other manufacturers seem quite happy to disclose this information though.

Ive been looking for a replacement outer chainring and I fancy something made from 7075 T6 alloy (Zircal) as it harder wearing then 5083 alloy (Dural).

Meanwhile Ive found one at a great price https://www.spacycles.co.uk/m2b0s210p30 ... cral-Outer

Brucey
Posts: 32690
Joined: 4 Jan 2012, 6:25pm

Re: Shimano 105 Chainring - Alloy specification ?

Postby Brucey » 16 Jan 2019, 3:05pm

5083 is not 'dural'.

Dural is a generic name for aluminium alloys that have a primary (not trace) addition of copper, i.e. they are 2xxx alloys not 5xxx alloys. Most dural grades are quite a lot harder than 5083, so manufacturers calling their 5083 chainrings 'dural' are not just guilty of a 'terminological inexactude' (i.e. a lie) it is a misleading lie.

However for many years 105 specification chainrings have been softer and more corrosion resistant than (say) Dura-Ace chainrings so they probably are made from 5083.

7xxx alloy chainrings are harder wearing for sure than 5083 ones, but the thing that knackers chainrings faster than anything else is dirty, worn chains. You can get about 15000 mile from 5083 chainrings and about double that with 7xxx ones, if the chain is kept clean and is binned when it is worn. You can ruin the same chainrings in a quarter of the mileage if you let the chain get worn out.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Jules59
Posts: 2
Joined: 16 Jan 2019, 2:34pm

Re: Shimano 105 Chainring - Alloy specification ?

Postby Jules59 » 16 Jan 2019, 10:43pm

Thanks for that.
Wiki says "Dural" refers to 2000 series alloys, but gives no trade name for 5083 alloy.

Stronglight make "Dural 5083 chainrings" -and they are advertised widely as that, eg:

https://www.ribblecycles.co.uk/strongli ... chainring/

So you see my reason for my error.

Perhaps someone should tell Stronglight about their terminological inexactude :D

Why do you think Shimano seem reluctant to display the alloys they use ?

Brucey
Posts: 32690
Joined: 4 Jan 2012, 6:25pm

Re: Shimano 105 Chainring - Alloy specification ?

Postby Brucey » 16 Jan 2019, 10:56pm

yes the mystery of why stronglight use the wrong term for the material in their chainrings has been raised before.

As to why shimano don't quote material specifications.... they don't have to. If you buy a 105 chainring probably you will do so because it has exactly the same pins ramps and offsets on as the original one, so it will fit and work perfectly. Aftermarket chainrings.... not so much. Shifting is rarely quite as sweet with an aftermarket chainring.
If they fit and work well enough, zicral chainrings do wear well. Unfortunately in 10/11s chainsets especially, the offsets/dishing of the chainrings is often not exactly replicated in aftermarket chainrings, so folk sometimes find that there are weird happenstances such as the chain 'riding' on middle/inner chainrings from other manufacturers, or when the OEM chainrings are mixed with others.

With 9s I'd probably have a go but with 10s I'd be less sure that an aftermarket chainring is going to work, but if I changed a single chainring for an aftermarket one, it'd be the outer.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

bgnukem
Posts: 119
Joined: 20 Dec 2010, 5:21pm

Re: Shimano 105 Chainring - Alloy specification ?

Postby bgnukem » 17 Jan 2019, 11:51am

Having used the Spa 7075 'rings on my winter bike for a couple of winters I find them very good, with a good quick shift. Having used TA and also Stronglight Zicral rings previously I reckon the Spa shift at least as well.

Just bought a set of 3 for my commuter for about £51 which is little more than the cost of a single outer TA 'ring.

Can't compare lives as I can't remember total mileages but I guess given a similar alloy a similar hardness would be expected.

I tend to aim for about 12-13k from a transmission before replacement, using 3 chains in rotation, and IME usually the cassette wears first and the chain starts skipping, probably due to riding in the same three sprockets for most of the mileage.