48/32 10 speed question

[si_c]

https://singletrackworld.com/forum/bike-forum/grx-10sp-pull-ratio/

Hmmmmm this thread suggests it is a right mess, seems to me like you need grx shifters, front mech and rear mech for pristine shifting, appears 10 spd 105 shifters aren't a great match

Probably don't need a GRX shifter, can get away with regular 105 - might not be perfect but it'll shift well enough. The issue will be getting a new chainset for the subcompact setup.

 

[CXRAndy]

How is the gear shifting if you go 46/30 ?

As long as you can move the front derailleur further down the seat post, there will be no problems.

Id look at 46/30 or 44/28 if available. The top speed will not be compromised on the flat and you will have a lovely set of low gears for climbing hills- the latter will allow you to dial back your efforts and have a higher cadence.

Have a look at bikecalc.com. You can punch in all sorts of ratios, it will give you gear inches, ratios, speed at certain cadences in all the ratios of your desired setup, everything really

I use it to work out my touring bikes gearing. I ended up with a triple crank 48/36/26 and a 11-40 or 11-32 cassette for differing events

 

[T4tomo]

With shimano 5700 105 shifters , ultegra front mech, and 5700 med cage rear derailleur,any reason for poor shifting using 46/30 grx front rings seeing as I don't have grx shifters ?

GRX shifters is a red herring as the FD pull ratio is identical to rest of shimano range.

What may effect shifting is the front mech, as the GRX chainline is marginally wider than the road series chainsets (to allow for clearance of wider tyres) so your FD may not have enough swing to get the big ring. With a Sq taper BB yu could just use a short axle BB, but with Hollowtech II you cant change that. but then a GRX front mech isn't too expensive anyway.

Spa cycles do a range of "sub compact" chainsets, but they are for square taper BB's so then you'd need a new BB (and if your BB is press fit your farked - but if its thread its OK, you trade better longevity for more weight vs HT II)

 

[Guitars and Bikes]

So if I bought the grx 46 and 30 chainrings and fitted them to my 105 5700 spider, kept 105 5700 shifters and hollowtech ii bottom bracket, and medium 5700 rear mech.......but changed my ultegra front mech for a grx one, would this give me nice gear shifts or a bit iffy ?

 

[T4tomo]

So if I bought the grx 46 and 30 chainrings and fitted them to my 105 5700 spider, kept 105 5700 shifters and hollowtech ii bottom bracket, and medium 5700 rear mech.......but changed my ultegra front mech for a grx one, would this give me nice gear shifts or a bit iffy ?

I think if you bough the GRX chainrings only you wouldn't need to swap front Mechs, but do GRX chainrings fit 5700 spider??? I suspect not otherwise we'd all be swapping to that 30 inner - I thing the BCDs are different as the small inner you can is 33T onto a standard road chainset.
(yes the 30T chainrings need an 80BCD fitting which is only on the GRX spider)

I was suggesting buy the whole GRX chainset and

kept 105 5700 shifters and hollowtech ii bottom bracket, and medium 5700 rear mech.......but changed my ultegra front mech for a grx one,

which would work cushty

 

[fossyant]

So if I bought the grx 46 and 30 chainrings and fitted them to my 105 5700 spider, kept 105 5700 shifters and hollowtech ii bottom bracket, and medium 5700 rear mech.......but changed my ultegra front mech for a grx one, would this give me nice gear shifts or a bit iffy ?

You haven't read the thread - with 110 BCD compact you can't go lower than 33T so they won't fit. You'll need a GRX chainset as well.

 

[fossyant]

Which 5700 rear is it ?. You can just about get the 5702 GS rear mech to work with a 34T rear cassette, otherwise it's 32T - I have a 5702 GS.

 

[T4tomo]

It possible also worth mentioning Shimano Cues Road / gravel range is now out, which is potentially an option. i dont know enough about compatibility but I think its supposed to be a cheaper version of GRX stuff. But there is also Cues for flat bars so you have to double check you are buying the right components I think the 6000 and 3000 series are the drop bar ranges.

 

[CXRAndy]

Just swap out the PF for and adaptor bottom bracket, which will take threaded cups. You could then use spacers to adjust for chain ring alignment

 

[Guitars and Bikes]

My bb isn't press fit, it's 105 hollowtech ii

 

[oxoman]

I did similar with my tcx cyclocross come gravel bike. TBH that was 11 spd, finally went single speed 38 x 42 I think with ultegra long rear mech. Still in use now. I managed to find I think it was a 30t that fitted the front crank so I think my last 2x was 46 / 30 changed ok but maxed out on 36 rear cassette. Didn't like small small or big big so thats why i went 1x.

 

[Guitars and Bikes]

So...,,,, buying grx chainset and front mech and keeping my 105 shifters , 105 rear mech and hollowtec ii bottom bracket will give nice shifting with no issues related to fact I'm using 105 shifters ?

 

[si_c]

So...,,,, buying grx chainset and front mech and keeping my 105 shifters , 105 rear mech and hollowtec ii bottom bracket will give nice shifting with no issues related to fact I'm using 105 shifters ?

Shouldn't do I don't think - I'd probably keep the 5700 front shifter though to see if it works before getting the GRX one.

 

[oxoman]

You should be able to just drop the front mech assuming it's band on type. Some fixed frame lugs might not go low enough.

 

[Punkawallah]

You should be able to just drop the front mech assuming it's band on type. Some fixed frame lugs might not go low enough.

You had to use the word ‘just’, didn’t you.

I swapped the 52/40 on my Galaxy for the Spa cycles 48/34. Feels a lot easier, especially on hills. No problem shifting. But that’s what you’d expect from the Suntour VX with downtube levers. . .
Just saying :-)