Chainring Replacement Instead of Crankset/Chainset Replacement

[Deleted member 35268]

I was looking to replace a Triple 9 speed crankset/chainset as the centre 39 tooth ring is very worn. Its a Shimano Sora unit.

A complete replacement is going to fetch at least £70.00 so I have decided just to swap out the middle ring - for just a tenner.

I've done this before and it is pretty easy so long as you can identify the right part with correct BCP, Model number, number of arms etc.

Hopefully my winter bike will be back in action by the weekend

 

[Paulus]

I was looking to replace a Triple 9 speed crankset/chainset as the centre 39 tooth ring is very worn. Its a Shimano Sora unit.

A complete replacement is going to fetch at least £70.00 so I have decided just to swap out the middle ring - for just a tenner.

I've done this before and it is pretty easy so long as you can identify the right part with correct BCP, Model number, number of arms etc.

Hopefully my winter bike will be back in action by the weekend

It's the cheapest option if the other rings are ok.
You may find that you need a new chain as that may of worn and might slip on the new ring.

 

[bbbbbbbbbbbbbbbbbbbb]

You may find that you need a new chain as that may of worn and might slip on the new ring.

.. plus cassette.

 

[Ian H]

I'd never consider replacing the entire chainset unless I'd broken it.

 

[Ajax Bay]

The middle ring tends to get the greatest wear.
https://sheldonbrown.com/cribsheet-bcd.html
Spa Cycles ftw (£6) for a 38t/110mm BCD: https://www.spacycles.co.uk/m8b0s210p4819/SPA-CYCLES-Alloy-Chainrings-38T-28T
I'm guessing 5-bolt and 130mm BCD (but could be 110mm (!£15)).
Edit (agreeing with @gbb): You don't need to replace the chain or the cassette when you change a ring. Cassette sprockets last maybe 3 chains so 7000km: chainrings last 25,000+km. A worn chain will cause faster wear on a chain ring tooth than a chain within the +0.75% elongation 'limit', but much less than the wear on each sprocket tooth: cod-maths analysis available.

 

[Deleted member 35268]

.. plus cassette.

Will do, and chain!

 

[roubaixtuesday]

The middle ring tends to get the greatest wear.
https://sheldonbrown.com/cribsheet-bcd.html
Spa Cycles ftw (£6) for a 38t/110mm BCD: https://www.spacycles.co.uk/m8b0s210p4819/SPA-CYCLES-Alloy-Chainrings-38T-28T
I'm guessing 5-bolt and 130mm BCD (but could be 110mm (!£15)).

If it's current Sora then I think that's also silly special Shimano bolt arrangement

https://www.sjscycles.co.uk/chainri...110mm-bcd-4-arm-middle-chainring-mr-type-39t/

 

[Deleted member 35268]

If it's current Sora then I think that's also silly special Shimano bolt arrangement

https://www.sjscycles.co.uk/chainri...110mm-bcd-4-arm-middle-chainring-mr-type-39t/

mines a 5 arm (he says, with the same amount of trepidation as I have to the carpet measurements I provided carpetright)

 

[gbb]

Will do, and chain!

From experience, I'd buy and fit a chain ring and use it and see, At worst, measure the chain wear make a decision on that. If its nearly worn out, replace, if its OK, I'd probably run it if it were mine. Cassette, I wouldn't generally replace until it gave problems.
6 and 2 threes, I used to work with a guy who replaced all three every year. He was a year round commuter and the extra cost gave him some certainty and problem free running for the next year, plus it was still cheaper that his bus fares.

 

[T4tomo]

mines a 5 arm (he says, with the same amount of trepidation as I have to the carpet measurements I provided carpetright)

https://www.sjscycles.co.uk/chainri...-bcd-5-arm-middle-chainring-d-type-black-39t/

just check its say FC-3503 on your current chain set somewhere before ordering!

 

[Deleted member 35268]

https://www.sjscycles.co.uk/chainri...-bcd-5-arm-middle-chainring-d-type-black-39t/

just check its say FC-3503 on your current chain set somewhere before ordering!

Thats the fella. Unfortunately I have broken a rule and replaced a black one with a silver one! Shock Horror

 

[T4tomo]

Thats the fella. Unfortunately I have broken a rule and replaced a black one with a silver one! Shock Horror

to be fair, the middle ring is the least visible, so we wont send the cycle fashion police round just yet...

 

[Ming the Merciless]

For replacement chain ring bolts, SPA have stainless steel ones at a good price. You want both the sleeve and head. Go for the longer options for the double / triple chain rings, the inner chain ring uses the shorter bolt.

 

[Pat "5mph"]

Thats the fella. Unfortunately I have broken a rule and replaced a black one with a silver one! Shock Horror

No worries: I just got my LBS to do the same as you, but they could not find a new chainring in stock to order, so they used (with my permission, of course) a black chainring from a donated bike.
The whole drivetrain is already black from the couple of weeks commute since it was fitted

 

[Fastpedaller]

For replacement chain ring bolts, SPA have stainless steel ones at a good price. You want both the sleeve and head. Go for the longer options for the double / triple chain rings, the inner chain ring uses the shorter bolt.

Not available at the moment