Replacing chainrings in crankset

[arupaka]

Hi everyone,

Doing some well needed maintenance on my GT Traffic 3.0. After replacing the chain and riding for a bit it was clear the cassette and crank chainrings are good as trash.
The crankset has 3 chainrings (28-38-48): the granny has very sharp teeth and the mid is kinda ok? Well, I was trying to get away with only replacing the granny, but so far couldn't find anything that looks similar, the ones I find are all flat and the one I have has kind of a dish shape. Besides, I have no idea how I would separate both since the "bolt" hole is simply a circle and no tool seems to grip.

So right now I'm thinking if it's even worth trying to go this way. Other solution would be to get a new crankset, something like Altus M311 or Acera M361.
I don't mind buying a new one, but the one I have now is still decent apart from the inner chainring, so it feels like a waste.

Some pictures for context





Thanks!

[rareposter]

It's usually easier and cheaper on entry level bikes like that to replace the entire chainset. Messing around trying to find individual rings, especially when they all need changing anyway, is a recipe for extra cost and complexity as there are any number of compatibility issues.

Altus or Acera chainset would fit the bill perfectly.

As an aside, on the front they're called chainrings, not sprockets. Sprockets are the sharp spinny things at the back. Chainrings for the sharp spinny things up the front.

And if you're changing chainset and chain, you'll need a new cassette too - again you just buy a whole new one, not individual sprockets. So long as it's the same number of sprockets and basically the same ratios to within a few teeth, it'll be fine.

[arupaka]

It's usually easier and cheaper on entry level bikes like that to replace the entire chainset. Messing around trying to find individual rings, especially when they all need changing anyway, is a recipe for extra cost and complexity as there are any number of compatibility issues.

Altus or Acera chainset would fit the bill perfectly.

As an aside, on the front they're called chainrings, not sprockets. Sprockets are the sharp spinny things at the back. Chainrings for the sharp spinny things up the front.

And if you're changing chainset and chain, you'll need a new cassette too - again you just buy a whole new one, not individual sprockets. So long as it's the same number of sprockets and basically the same ratios to within a few teeth, it'll be fine.

Thanks for that, post is edited
Yeah the cassette is completely dead, will probably get everything new. As you said about replacing the chainrings, seems like too much effort to even bother...

One other thing, I shouldn't have to worry about the bottom bracket right?

[gregoryoftours]

The chainrings are riveted together on that chainset so you couldn't replace them anyway. You may need a new bottom bracket as the chainring offset may well be different on a different chainset.

[arupaka]

The chainrings are riveted together on that chainset so you couldn't replace them anyway. You may need a new bottom bracket as the chainring offset may well be different on a different chainset.

That's what I thought!

Silly question, but does this come with the left arm ?

https://www.bike24.com/p260442.html

[Paulatic]

[

Silly question, but does this come with the left arm ?

https://www.bike24.com/p260442.html

Yes, it says crankset

[rareposter]

Silly question, but does this come with the left arm ?

https://www.bike24.com/p260442.html

Yes, it does but be aware that the chainrings are significantly smaller than the 28/38/48 you currently have which means:
a) lower gears overall
b) you'll need to drop the front mech down a bit to get the front shifting to work properly.

[plancashire]

The chainrings are riveted together on that chainset so you couldn't replace them anyway. You may need a new bottom bracket as the chainring offset may well be different on a different chainset.

Are you sure? In the picture I reckon I can see a hex or torx socket inside the bolts. The bolts I have for my Truvativ chainset are fixed with hex "Allen" keys. You need one for each side. Isn't this the usual way anyway as the outside must be round to fit in the recessed hole in the chainring?

[kylecycler]

The chainrings are riveted together on that chainset so you couldn't replace them anyway. You may need a new bottom bracket as the chainring offset may well be different on a different chainset.

Are you sure? In the picture I reckon I can see a hex or torx socket inside the bolts. The bolts I have for my Truvativ chainset are fixed with hex "Allen" keys. You need one for each side. Isn't this the usual way anyway as the outside must be round to fit in the recessed hole in the chainring?

It might look like that in the photos but it's an odd arrangement - these SR Suntour chainsets were fitted to Carrera Subways and the middle and inner ring are riveted together (big round rivets), with bolts passing through the spider and the separate outer ring into threaded holes in the middle ring.

I just replaced one the other week and although SR Suntour's specs said it should have a 122mm BB, mine had a 118mm BB (from new), although everything had lined up fine and it worked perfectly, it was just worn out.

I thought I was replacing more or less like for like with another basic SR Suntour chainset but the 118mm BB was too short - the original chainset flared out more on the inside than the new one so was wider - so I needed a 122mm BB, although that was what was specced for the BB anyway.

Fortunately I found a new 122mm BB I've no recollection of buying or for what, so it turned out ok.

I think it's likely that the OP's SR Suntour chainset might be matched with a 122mm BB but I wouldn't know for sure (maybe a 118mm).