swapping a crankset - do I need other changes?

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1982john
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swapping a crankset - do I need other changes?

Post by 1982john »

On my Topstone, I'm looking to change the fsa 46/30 for the grx 600 46/30. I'm also going to be changing the chain. The bike has the Tiagra derailers it came with - wll they be ok wth the new chankset?
JohnMorgan
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Joined: 9 Jun 2022, 7:19pm

Re: swapping a crankset - do I need other changes?

Post by JohnMorgan »

Should be no problem regards the derailleur, the number of teeth are the same.

Is the mount for the chainring the same?
slowster
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Re: swapping a crankset - do I need other changes?

Post by slowster »

I think GRX double chainsets have a 2.5mm wider chainline than standard Shimano road doubles (FSA might be different), and the GRX front derailleurs are designed for that wider chainine. I don't know how significant the difference between a GRX front derailleur and a standard road front derailleur would be in practice.
Valbrona
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Re: swapping a crankset - do I need other changes?

Post by Valbrona »

As per previous posts, the GRX crankset might give 2.5mm wider chainline. Might not ... because wider chainlines are becoming the norm owing to the popularity of bikes with disc brakes (wider spacing at the rear).

You'll be mighty unlucky if your Tiagra FD doesn't give enough out-swing to work properly, but you might not actually find out for sure until you fit your new crankset.
I should coco.
TheBomber
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Re: swapping a crankset - do I need other changes?

Post by TheBomber »

1982john wrote: 23 Feb 2023, 12:20pm The bike has the Tiagra derailers it came with - wll they be ok wth the new chankset?
Yes: https://productinfo.shimano.com/#/com?c ... acid=C-455 Scroll down to the '2x10-Speed' section.

But as described above (and in the linked Shimano tech doc) your front mech is not fully compatible. But might work.

tech doc also confirms that the bottom bracket should be fine.
1982john
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Re: swapping a crankset - do I need other changes?

Post by 1982john »

thanks for the replies. I've also done some reading on topstone forums and apparently it's really hard to remove the FSA one as well :o
TheBomber
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Re: swapping a crankset - do I need other changes?

Post by TheBomber »

Do they say why?

And as a possibly now irrelevant addendum to my earlier comment about the BB - you presumably will need a new one as your existing won’t be the Tiagra version that I was reading of the tech doc.
Jupestar
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Re: swapping a crankset - do I need other changes?

Post by Jupestar »

1982john wrote: 23 Feb 2023, 7:36pm thanks for the replies. I've also done some reading on topstone forums and apparently it's really hard to remove the FSA one as well :o
Presumably this is because FSA seem to make their axles 24.001mm.
1982john
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Re: swapping a crankset - do I need other changes?

Post by 1982john »

TheBomber wrote: 23 Feb 2023, 8:03pm Do they say why?

And as a possibly now irrelevant addendum to my earlier comment about the BB - you presumably will need a new one as your existing won’t be the Tiagra version that I was reading of the tech doc.
comes over torqued from the factory
Sooper8
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Re: swapping a crankset - do I need other changes?

Post by Sooper8 »

1982john wrote: 23 Feb 2023, 7:36pm thanks for the replies. I've also done some reading on topstone forums and apparently it's really hard to remove the FSA one as well :o
Is there a dedicated Topstone forum? If so, would you care to share the link, I am about to buy and would like to ask questions and seek some info that might be a bit specific here
mxg01
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Joined: 18 May 2018, 2:55pm

Re: swapping a crankset - do I need other changes?

Post by mxg01 »

There is this group on Reddit. It's pretty informative.

https://www.reddit.com/r/Topstowners/
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