Chainring question?

[Saracenlad]

Can anyone help please. I have a Shimano Sora chainset and want to replace the 50 ring outer with a 42. Found several rings with the correct BCD of 110. Some are specific "inner" or "Mid" Why? Thanks, Ken.

 

[si_c]

Can anyone help please. I have a Shimano Sora chainset and want to replace the 50 ring outer with a 42. Found several rings with the correct BCD of 110. Some are specific "inner" or "Mid" Why? Thanks, Ken.

It's mostly to do with the position of the ramps and pins which help the chain move when changing gear, but for mid/inners it can also be the position of the bolts on a triple chainset.

For the Shimano Sora, you'll may find that the outer chainring also has captive chainring bolts, so you only need some on the inside in which case if you change the chainring for a non-Sora one then you will need additional chainring bolts.

 

[Saracenlad]

It's mostly to do with the position of the ramps and pins which help the chain move when changing gear, but for mid/inners it can also be the position of the bolts on a triple chainset.

For the Shimano Sora, you'll may find that the outer chainring also has captive chainring bolts, so you only need some on the inside in which case if you change the chainring for a non-Sora one then you will need additional chainring bolts.

Thanks for that. Should have said it is a double chainset. The 50T is just too big. Both outer and Inner are bolted to the spider with the same blots. I will keep looking.

 

[Spiderweb]

If 5 bolts then this will be suitable (available in both black and silver);
https://www.spacycles.co.uk/m8b0s210p3054/SPA-CYCLES-110-BCD-Zicral-Outer-Chainring

 

[Chislenko]

Why not look for a cheap chainset. Presuming your Sora is nine speed and square taper, a quick search threw up a 46-30 alternative at £40.

There will probably be other combinations.

 

[twentysix by twentyfive]

If 5 bolts then this will be suitable (available in both black and silver);
https://www.spacycles.co.uk/m8b0s210p3054/SPA-CYCLES-110-BCD-Zicral-Outer-Chainring

View attachment 667306

Spa Cycles is a very good call for chainrings. My go to shop.

Sometimes https://www.sjscycles.co.uk/ are useful

 

[T4tomo]

Why not look for a cheap chainset. Presuming your Sora is nine speed and square taper, a quick search threw up a 46-30 alternative at £40.

There will probably be other combinations.

and running 46-30 makes more sense than 42-34 (presuming your inner ring is usual compact 34)

 

[Saracenlad]

Thanks for the help. New ring on way from Spa Cycles.