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Am I right in thinking 10 speed road and mtb have different cable pull? Want to use an 11-46 cassette.
Right, a bit of reading suggests mtb 1.7 vs road 1.2, so these wouldn't work on a wide range cassette. Ah well.
I think the max was 36t from my old gravel bike with R4700.
Thanks, I've got 11-42 (not 46) 8 speed on at the moment which is fine but a bit agricultural.
The shifter won't be the issue, it'll be the derailleur that the shifter is operating. Most people seem to report that the 4700 rear mech will play just fine up to a 36t cassette low gear, the 4700 shifters also work fine with GRX RX400 series mechs and whilst I don't know what the GRX rear mech is rated to I suspect you could get close to 42t, this all being 10 speed though, won't work with 8 speed, but reading that last post i'm guessing you are looking at upgrading.
The 10sp MTB cassette apparently is fine with Tiagra 4700.
I'll let you know how it goes next month with a new 10sp MTB cassette and goat link - but according to the thread I started last month, it all works fine.
I have a 10 speed 36T SLX cassette on my 4700 drivetrain, I reckon the GS mech will do slightly bigger than that without having to use a goat link/extender, maybe 40T at a squeeze
Yep I run an 11-40 Deore MTB cassette with 4700 shifters and mech, can't speak for an 11-46 but it works fine in terms of pull and spacing. I use a cheapo extender:
https://www.merlincycles.com/sunrace-rear-derailleur-extender-link-134836.html
Does anyone know if the 4600 10 speed is a the same as above. I’ve got a gravel bike at my Dads with a 4600 road groupset that I’d like a better range of gears.
Also need smaller front cogs
The bike is in Greece, so I need to get everything I need to take when I go next time.
A hanger extender like a Goat Link with the existing mech might work, or use a 10 spd MTB mech and a Wolftooth Tanpan - I think the 4700 needs an 11 spd version (as cable pull is same as 11 spd Road) and 4600 needs the 10 spd version.
Cool, worth a try then. For the record, currently running 1X with an 8 speed Claris shifter, a 9 speed Sora mech and an 11-42 Sunrace cassette which has been mostly fine. Another reason for wanting to upgrade though is to put on a derailleur with a clutch as the chain has started dropping off in top gear. GRX RX400 looks good.
I might be looking at the chainring as the culprit given the way you phrased that.
Do you already have the Tiagra kit? If not, why not look at alternatives where the drop bar shifter and mech are designed to work across wide range cassettes from the start?
https://www.microshift.com/products/groups/advent-x/
Their 9 speed groupset also has drop bar 11-46 options.
https://www.microshift.com/products/groups/advent/
I run Tiagra shifters with a mtb 11 36 cassette. No problems. Currently with a 105 derailleur
It might be useful to know
1. All grx derailleurs are the same pull ratio as Tiagra 4700, as are all shimano 11 speed road. Some grx derailleurs are rated to 42 teeth and go bigger
2. If you have a threaded bottom bracket then spa cycles will build any chainset ratios you want for about £80. Mine is 38-26
I looked at what Montgomery is suggesting - it is a great option.
However, with a £30 Ribble sale GRX crank I decided to stay with 2x for a) wider gear range and b) slightly cheaper.
Mrs_oab has the Advent-x on her Marin and, apart from being a touch clunky* sounding in action and lower top end, is superb.
.
*I think it has quite a snappy set of springs on it.
Tiagra shifters appeared on gumtree locally, which is what got me thinking. Have ordered a GRX mech off ebay. The Microshift stuff looks nice but the gear cable is external and would interfere with a bar bag. Again for the record the newer Claris runs it under the bar tape. Cheap and cheerful. Of course it might just be case of changing the chain ring...