Update on replacing 48/32 crankset with 36/22 crankset

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 elsewhere 01 Sep 2022

So it works, with some chain rattling in front mech for certain gears. 

OP elsewhere 01 Sep 2022

ORIGINAL POST FROM 18thJune

https://www.ukhillwalking.com/forums/biking/replace_4832_crankset_with_3622_cr...

Getting jealous of my mate's low gears on his MTB compared to my cyclo-cross bike when he cycles and I walk.

9 speed cassette 11-34 I think. The bike is ridden pretty much exclusively off-road, top gear is nice for bouncing at speed on good gravel but rarely used.

I have FSA Vero (road?) with 48 and 32 teeth chainrings and FSA bottom bracket.

Shimano Altus FC-MT101 (MTB?) chainset 36/22T looks like a reasonable option for significantly lower gears. Is this a dumb idea?

Anybody know if bottom bracket compatible between Vero and Altus?

Is there a chainline issue (length of bottom bracket axle?) or some road Vs MTB issue?

Would Shimano Sora front mech need changing or just lowered on down tube?

Any impact in rear mech?

Lots of questions as I have no idea!

OP elsewhere 01 Sep 2022
In reply to elsewhere:

Lots of useful input from others on original thread concluding on 22nd June with

It looks like the following should be compatible with existing square taper bottom bracket, current 11-34 cassette, rear mech capacity, frame geometry(?)...

Shimano Altus FC-MT101 chainset 36/22T

SHIMANO ALTUS TOP SWING Front Derailleur (Clamp Band Mount) 2x9-speed 

https://bike.shimano.com/en-EU/product/component/shimano/FC-MT101-2.html 

https://bike.shimano.com/en-EU/product/component/altus-m2000/FD-M2020-TS.ht... 

Fitted the chainset today - all good.

Shortened chain 

Front mech DID NOT FIT

The cable path and adjustment screws are behind the seat tube so suitable for bike (MTB, hybrid) with much more space between tyre and seat tube.

The old Sora road mech has cable path and adjustment screws more to drive side of seat tube and above chainrings rather than behind seat tube. The spec is for much bigger chainrings such as 48-32 and the cage around the chain is much longer. Moved  Sora mech down 22mm ISH until cage almost fouls chainstay and 7mm ISH above chainring. 

Lowest gear works ok, top gear some chain-front mech rubbing. Small small cross chaining some rubbing. Large large cross chaining ok.

Conclusion - if anybody tries this, give it a go with existing front mech before you buy a new front mech. Front mech compatibly is complicated and the conventional option of changing cassette and gear hanger extender if needed is a safer option.

Post edited at 17:10
 magma 04 Sep 2022
In reply to elsewhere:

glad its worked out. maybe a slight adjustment of the mech position would sort rattling? thinking of something similar to replace my fsa 50/34. i'd offer to buy your 48/32 but too little difference. maybe a 46/30. hmm

OP elsewhere 04 Sep 2022
In reply to magma:

I'll give it a fiddle but the front mech is used so far out of spec I'm not sure it can be rattle free. Haven't managed to test it yet on the local climb 25% ISH that usually defeats me.

Maybe I should just bend it to increase the clearance!

Post edited at 19:55
 Hooo 04 Sep 2022
In reply to elsewhere:

Thanks for the update. I went for the easy option of changing the cassette for an 11-40. No hanger extender needed, I just had to fit a longer chain. Half a turn of the B-screw and it was done. It actually changes better than it did before, probably because my chain needed replacing anyway. The only downside is due to the slacker chain it slaps about a bit when I stop pedalling in top gear. 

OP elsewhere 04 Sep 2022
In reply to Hooo:

That sounds easy and therefore nice!

 beardy mike 05 Sep 2022
In reply to elsewhere:

If you change again in the future, it's worth looking at the Microshift Advent x system as it's a 1x system so you no longer have any front mech issues but have MTB shifting capacity, and a clutch derailleur which helps with chain retention offroad and quietness. 

Currently on my gravel bike I run a Shimano MTB XT 10speed derailleur, a SunRace 10 speed 11-46 Cassette and a 42 tooth chainring (which is too big of serious offroad - I think I need to drop to 36)... with a Microshift barend shifter which is shimano MTB compatible. It works pretty well other than shifting offroad with the barend shifter is a bit rubbish. But it was from before Advent existed... had that option been available...

Also SRAM 10sp road is compatible with 10sp MTB...

Post edited at 09:11
 magma 05 Sep 2022
In reply to elsewhere:

> Maybe I should just bend it to increase the clearance!

did you try twisting the FD around the tube slightly as well as up/down? does the chainline look ok? no big deal if you're not meant to use those gears anyway?

 magma 05 Sep 2022
In reply to Hooo:

> Thanks for the update. I went for the easy option of changing the cassette for an 11-40.

not sure a 11-40 9 speed cassette is available? possibly 11-36?

 beardy mike 05 Sep 2022
In reply to magma:

https://sunrace.com/product/csm980-9ax/

I have one on an old Marin P{ine Mountain.

 Hooo 05 Sep 2022
In reply to magma:

This is the one I got, and I'm very happy with it: https://airbike.uk/collections/9-speed-cassette/products/9-speed-mtb-casset...

 magma 06 Sep 2022
In reply to Hooo:

ahh, didn't know about that. even a 11-42t is available. outside the recommended range for my shimano rd (deore m-592) but should work?

Post edited at 13:11
 Hooo 06 Sep 2022
In reply to magma:

Cheap enough to be worth a go? My derailleur is supposed to only go up to 36, but I saw a blog post where someone had tried a 40 and it worked, so I gave it a go.


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