MegaSack DRAW - This year's winner is user - rgwb
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I would really like a 10 x 2 speed Shimano GRX groupset (Tiagra equivalent) on my winter/All road bike, but getting hold of one is almost impossible at the moment. However Tiagra parts frequently pop up on ebay so i was wondering if i could put GRX chain rings (46/31 I think) on to Tiagra 4700 chainset that would most likely be a compact (50/34)?
Thanks.
No, you can't
Back to the drawing board then.
Mmm.. all may not be lost, unless I'm mistaken (quite possible) Tiagra 4700 has the same 4 bolt 110 BCD and asymmetric pattern as the current 105/Ultegra/DA, 46t aftermarket chainrings are available for those so should fit fine, would enable me to run 46/34 up front. If I had been able to use a 30t inner ring it would have been paired with a 12-32 cassette, the 4700 long cage mech is rated to 34t and Shimano are notoriously conservative with their guidelines, I would have thought it possible to get a 12-36 cassette to work which is close enough for me.
Any obvious that I've overlooked?
The RX400 mech is rated to 36t so why not use that?
4700 long cage mech will almost certainly work with 11-36. If not it will with an extender like this:
https://www.sjscycles.co.uk/gear-spares/sunrace-rear-mech-extended-link-for-wide-ratio-cassettes/
I'm running 11-40 with a long cage 4700 mech no problems using one
SJS also have a few GRX chainsets in stock depending what crank length you want!
The RX400 mech is rated to 36t so why not use that?
Will they work fine with 4700 shifters?
SJS also have a few GRX chainsets in stock depending what crank length you want!
Aren't the GRX chainsets spaced slightly differently to road chainsets?
<blockquoteWill they work fine with 4700 shifters?
Yes
Aren’t the GRX chainsets spaced slightly differently to road chainsets?
Yes. They have a wider chainline (by 2mm). In theory you'll need a GRX front mech
I think I read somewhere that you have to file a bit of the crank to get aftermarket rings to fit.
Isn't this something the EU should be looking into under right to repair or similar. It is starting to become annoying.
Thanks @simondbarnes you contribution has been very helpful and informative👍