Shimano GRX or 105 ...
 

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Shimano GRX or 105 on gravel bike?

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 DrJ
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Heeelp - too many choices. I'll be using the bike on road, forestry roads, bridleways. Which grooupset? And does it actually make any difference at the end of the day?

Sorry for all the questions and handholding requests - I'll get a life soon, I promise!


 
Posted : 08/10/2022 6:38 pm
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GRX

It's very nice


 
Posted : 08/10/2022 6:40 pm
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GRX, levers are better shape for off road, as are the ratios on the chainset. If 1 x the rear mech has a clutch too


 
Posted : 08/10/2022 6:43 pm
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If you get the opportunity feel up someone's shifters.

I've got GRX on my gravel bike and Mrs has 105 hydraulics her bike which are much more comfy for me.
Like saddles, it'll be very much personal preference.


 
Posted : 08/10/2022 6:46 pm
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I like the grx levers - good feel to them.


 
Posted : 08/10/2022 6:48 pm
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I have 2x grx on my gravel bike which also my touring bike and my commuting bike. I like it more than the 105 on my old bike.

The top level grx is ultegra level so should be nicer than 105 (not that there’s much in it).


 
Posted : 08/10/2022 6:54 pm
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GRX 2x

So good I've now got it on a road bike


 
Posted : 08/10/2022 7:00 pm
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Any plans for a dropper?
1x or 2x drive?


 
Posted : 08/10/2022 7:44 pm
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GRX; 2-3mm wider chainline for fatter rear tyres
2x for gravel/winter/commute


 
Posted : 08/10/2022 8:06 pm
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GRX I reckon.

1x for simplicity of riding/cleaning, 2x if you want to keep pace with anyone else on those road/commute bits.


 
Posted : 08/10/2022 8:41 pm
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The 2x10 GRX works nicely and comes with a clutch mech(I'm not convinced it's necessary though). I think it's equivalent of Tiagra so 105 should in theory be better


 
Posted : 08/10/2022 8:50 pm
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By all accounts you should be fitting at least Dura Ace Di2 12 speed with a 53t big ring, max of 420mm wide bars and 40mm deep carbon wheels to your road bike with 35mm tubeless tyres with an insert in at least the rear 😉


 
Posted : 08/10/2022 8:52 pm
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Well the brake callipers are identical bar paint colour, so don't let that sway you!

My gravel bike came with 105 groupset bar a Praxis chainset, as GRX wasn't out then and can't say I notice any issues with it. One of my brake callipers died and I could only find GRX available, so installed that - absolutely identical.


 
Posted : 08/10/2022 8:55 pm
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Clutch and narrow wide chain ring avoids the dreaded rattle on descents. I'd go with GRX.

Although maybe give SRAM Rival or Force gravel a look if you like double tap or you can find it at a good price.

I've have had GRX on my cross bike for the last 2 years but had to replace the front brake caliper as it got leaky seals. Fitted a Hope one and it's been great since.


 
Posted : 08/10/2022 11:10 pm
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Another thing to think about is whether you want a single or double ring up front. I chose a single ring and it was the right choice for 90% of my riding but can be a bit under geared when riding on the road with pals with road bikes. Or over geared when riding either steep long climbs or bigger days out.


 
Posted : 08/10/2022 11:15 pm
 timf
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You can mix between the two if you want.


 
Posted : 08/10/2022 11:22 pm
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They're completely interchangeable and in fact the brake calipers are identical.

The main difference is that the shifter hoods on GRX are a bit bigger and deeper for more stability on bumpy trails.

Obviously the chainset as well, GRX is wider spaced for better clearance and has narrow/wide teeth, smaller ratios etc.

My CX bike is running a right old mix of Shimano but the newish GRX levers have been great.


 
Posted : 08/10/2022 11:47 pm
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Erm, they aren't quite completely interchangeable. GRX has a 2.5mm wider chainset / front mech spacing than 105 / Ultegra. Not much but enough to require a GRX front mech if you decide to lower the gears and fit a 46/30 GRX chainset to the road groupset on your gravel bike.


 
Posted : 09/10/2022 1:49 am
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You can mix between the two if you want.

Yep. I had a GRX 1x chainset but 105 cassette as I prefer closing spacing of lower range cassette and as I don't ride up walls the 40/28 was low enough while the 40/11 was high enough.


 
Posted : 09/10/2022 7:09 am
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Another thing to think about is whether you want a single or double ring up front. I chose a single ring and it was the right choice for 90% of my riding but can be a bit under geared when riding on the road with pals with road bikes. Or over geared when riding either steep long climbs or bigger days out.

Maybe 4 years ago a lot of our club riders got 1x gravel bikes as their winter road bikes - bigger tyres/mudguard mounts etc. Quite a few reported the gearing, and steps between gears, made 1x harder work on a road ride. Obviously depends on how you intend to use it, but worth bearing in mind.


 
Posted : 09/10/2022 8:31 am
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GRX 2x with Ultegra cassette here, but I switch between flattish gravel and winter roads. Not sure if the difference still applies on current models but brake hoods and brake level pivot position on GRX feel superior for off road


 
Posted : 09/10/2022 8:40 am
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I’ve got 105 2x11 on my Topstone - I fully expected it to be noisy and annoying off road (due to the lack of a clutch) but it’s excellent. A lot of my gravel riding is pushing the limits of the bike on mtb territory so it’s been a solid test.

I’ve got a FSA chain set @ 46/32 and 105 11-34 cassette for a nice easy gear.

I think I’d just go with whatever I could get cheaper at the time.


 
Posted : 09/10/2022 10:09 am

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