Easiest way to make road gearing more mountainy?

You could fit a GRX double chainset with 46/30 rings and a 12-36 cassette, you'll need a GRX front mech but it'll work fine with Tiagra shifters.

Change the chainset for a sub-compact eg 30/44. You may struggle to get a bigger cassette to work with a road mech unless it’s an SGS model + you’ll need a longer chain.

You might need the Wolf Tooth Road Link rather than the Goat Link as I think that's only for 1x.

I have Tiagra on my gravel bike and remember watching some videos to see if I could go bigger than the 11-34t on mine, so check YouTube as it's definitely possible.

Will a Tiagra rear mech cope with a 42t?  I doubt it… I have a GRX groupset that can cope with 31/48 (or 30/46)  at front and 11-40 at rear on my ‘all-roads’ bike, not sure a road mech would allow a 40 or 42, 36 at best I’d have thought.

Nine speed MTB mechs are supposed to work with 10 speed road levers, never tried it myself. Also seem to recall the exact flavour of tiagra might be an issue. Got an old xt mech in the box?

I'm running a 52-34 on the front with no issues found although i'm old school in backing off the pressure when changing.  That's Ultegra rather than Tiagra but I don't see why it wouldn't work ok.  Not a huge difference but does help a little.

Nine speed MTB mechs are supposed to work with 10 speed road levers, never tried it myself. Also seem to recall the exact flavour of tiagra might be an issue. Got an old xt mech in the box?

I've got 2013 Tiagra (4600?). OE gearing was 50/34 and 11-28. I put an 11-34 cassette on with a 9sp Deore mech. Works fine. You could try squeezing a 36 on.

https://www.gear-calculator.com

You might need the Wolf Tooth Road Link rather than the Goat Link as I think that’s only for 1x.

I have Tiagra on my gravel bike and remember watching some videos to see if I could go bigger than the 11-34t on mine, so check YouTube as it’s definitely possible.

Here's a vid of a 40t + Road Link with a Tiagra RD.

Worth checking on Reddit too, as again I seem to remember ending up there when I was looking into it.

https://www.google.com/search?q=tiagra+11-42t+site:www.reddit.com

I also seem to remember Tiagra 4700 being a bit of an oddball when it comes to cross compatibility.

Tiagra - be careful, it's unique cable pull and limited in capacity at rear mech.

I managed to fit a a slightly larger cassette (iirc, it was 11-36) which maxed rear mech out, then dropped chainring sizes to 2 below minimum Tiagra could cope with.

If I did it again I would look to just replace all of Tiagra with a cheaper Microshift with additional capacity.
Or buy a different bike.

Tiagra – be careful, it’s unique cable pull and limited in capacity at rear mech.

IIRC it's the same pull as 11 speed, so not compatible with other 10 speed kit including older Tiagra.

Tiagra 10 speed levers work with very old 90's Road rear dérailleurs so might work with old mtb derailleurs too.

My old road bike has 10 speed tiagra levers with an ultegra derailleur from about 1998. Works fine.

Oh crikey, maybe I’ll just walk up the climbs.
It is a road link copy I think.
I’ll see if I can get some smaller front rings, I’ve got a new chain coming.

GRX looks cheap why would a tiagra front mech not work, it’s probably the quickest option as well.
Could I use an eleven speed chain set?

I am running absolute black supercompact 46/30 chainrings on a standard 7100 ultegra FD, and running a normal ultegra RD with 11-34 Ultegra cassette.

Previously I was running a standard 50-34 on a 6500Ultegra FD and a 9speed XT cassette (i think 34 biggest) with a wolf-tooth and 6500 standard medium cage RD

Citizenlee, thanks that video is very helpful.
Thanks for all the suggestions, I think hrd chainset makes the most sense.

10 speed tiagra worked for me with a 40 tooth cog but it was tight without an extender. Fit a wolf tooth type extender and it'll work grand with 42.

GRX looks cheap why would a tiagra front mech not work,

The GRX chainrings sit further out than those on road cranks.

Okay cheers SR
Thanks MrB

You'll probably get away with 34x34. No more than 34 at rear and a compact 110 BCD won't go below 33t at front.

Did this on my CX bike for 130 mile sportive. Climbs 1 in 4 (25%) ok.

Ok i have a tiagra bike

The big question is which Tiagra

47x0 is the newer stuff. That’s the same pull ratio as grx (10 and 11 speed) and all shimano 11 speed road.

The older stuff has the gear cable sticking out. Not under the tape. This is the one that works with the old 9 speed mtb mechs

All further comments are in the new stuff

I have a MTB block at the back, 11-36. No problems no extender.

At the front i have a spa cycles subcompact 26 38 chainset. They’ll make it with any ring size you want

I find it all works fine

A 42 tooth might by possible with a grx or shadow type rear mech

This might help

https://road.cc/content/feature/how-get-ultra-low-gearing-gravel-bike-adventures-246424

I fitted a lower geared rear cassette but had to change the rear mech side plates to make it longer to accommodate the spread. It was Ultegra though not Tiagra. SJS cycles do mech spares if they are available.

It’s the 4603 older 10 speed and I think the BCD is 130 so I can’t get a small inner ring, so I think grx chainset is the best option, please tell me I don’t need to change bottom bracket!

Thanks all

If you're running a 52/36 you will have a 110 BCD, as 130BCD is limited to 38T or bigger.

You could go down to a 33T with no issues, Specialities TA do them:

https://www.chickencyclekit.co.uk/shop/chainrings-bolts/110pcd-zephyr-8-9-10-11x-5-arm-inner/

A 33T little ring with an 11-34 cassette should get you up most stuff, but you may need a mech extender to get it to shift nicely.

@Blazin-saddles What flavour of GRX to you have? Does the rear mech go to 40 without an extender?

At the front i have a spa cycles subcompact 26 38 chainset.

I've been contemplating one of those for my Diverge, or as a dirt cheap tryout to see if I like the ratios a Shimano Cues for £35. Not sure the chainline is suitable though.

Schmiken looking at a photo, it is stamped with 52-B but I’m not sure if the inner size.

Play with the other end. I use MTB double chainsets or a triple and use the inner two rings. Chuck the outer away and drop the mech. Take a few links out once you have found out how big you can go at the back.

Mattsccm that’s a good idea, I could take one and see what works.

So I decided to double check the Chiggle stuff I bought.
Okay, just had a rummage, and found a few things- bit embarrassing really.
I’ve got:
Deore 10spd crankset 46/36
Micro shift 10 spd cassette- 11-36
10spd chain
10spd quick links
All brand new, boxed.
Will the Deore work with the Tiagra bottom bracket?
The cassette should work with the extender I hope.

For future googlers:
36t cassette (micro shift) needed the derailure extender (I used a Sunn, road link type thing) and a full 116 link chain. Shifts really well.
39 front 36 rear still not mountain ready for me, so next year I’ll plan better and bring a different crankset. An old ultegra 10spd triple would be the dream.

@Blazin-saddles What flavour of GRX to you have? Does the rear mech go to 40 without an extender?

mines a Di2 version but I think the geometry is the same between those and the cable versions.  Yes, no extender needed, just the b-tension screwed in a bit more.

Rear mech fine now on the 36t cassette I didn’t know I had (found in the Chiggle box). It’s the crank now needs sorting but I’m on a small Greek island so it’s a problem to deal with for the next trip.

An old ultegra 10spd triple would be the dream.

@jkomo - I have one in the garage. I replaced it with 2x11 when I wanted hydraulic brakes. I had it paired with a XTR 9 speed rear mech (which I alsdo still have) so that I could run a wide/low gearing range. If you're interested in these if/when you're back home, let me know.

Go and look on the CUK forum. You'll find millions of posts about this.

Thanks Scotroutes I would be interested in the crank and brifter, I think the rear mech is okay.

I'm just assembling the last few bits to try a 'low range' Tiagra 2x drivetrain on my gravel bike over winter (will also serve as a winter road bike).

I bought a Tiagra Triple chainset (130/74 BCD) which I plan to run with a 30t (inner) and a 46t (mid position) to effectively make it a "sub-compact" double (sticking to the 16t chainring difference rule).

I'll be running two wheelsets so probably 11-30 (maybe 11-32?) for the roadie wheels and 11-36 for the Gravel wheelset.

AIUI the trick is still just making sure the total tooth difference isn't too much, whether you're running 52/36, 50/34, 46/30 or even 44/28 keep the front to a maximum of 16t and you can probably stretch the rear mech a couple of teeth past the shimano approved maximum (34t with a double)... Interestingly the new GRX double comes in a 31/48t flavour.

I reckon a 30-36 ratio will be plenty low enough for me, I might even decide to play with 11-34 for gravel down the line... basically it gives me (cheap) options to tweak gearing range and increments.

This is all an experiment to better figure out a what I actually want from my next gravel bike (and possibly road) drivetrain which will no doubt be 2x12.

4700 Tiagra is relatively cheap, but still compatible with parts from the posher groups, Importantly you get hydraulic brakes (4720 levers). I've done 1x for gravel for a while (about a decade), it's adequate but I've started to notice the gaps and limitations.

This is the best set up I think Cookeaa, however the jockey wheels couldn’t get round the 36, this worked straight away:
SunRace Unisex Extended Link Derailleur accessory, Black, 2.25cm UK https://amzn.eu/d/fNDDD4d

MrsIHNs gravelly hybrid is now running 3x10 with the original 50/40/30 chainset up front and a 36t rear cassette (it was originally 25t), using the original circa 2009 Ultegra shifters/mechs.

All I did was buy one these for a fiver and a new chain. I didn't even have to fiddle with the indexing, it was ridiculously easy.