Just looking to see if anyone is running a 46/30 GRX with a 105 front der. Tech docs for GRX mention that there's a 2.5mm offset that needs to be accounted for (thus "justifying" a new GRX front der) or can you get away with it?
Looking to take my current 50/34 compact and run down to a 46/30 (with 11/28 in back) to pick up a few extra low gears. Eventually plan to move up to 11-32/34 if I need to. Don't think I'd need to replace rear der because I'm not changing 11/28 stock cassette out (yet).
Thoughts? Currently on a 2014 Jamis Renegade Expert.
Can't seem to find any clear answers anywhere, hoping some here has some insight!
Just looking to see if anyone is running a 46/30 GRX with a 105 front der. Tech docs for GRX mention that there's a 2.5mm offset that needs to be accounted for (thus "justifying" a new GRX front der) or can you get away with it?
Looking to take my current 50/34 compact and run down to a 46/30 (with 11/28 in back) to pick up a few extra low gears. Eventually plan to move up to 11-32/34 if I need to. Don't think I'd need to replace rear der because I'm not changing 11/28 stock cassette out (yet).
Thoughts? Currently on a 2014 Jamis Renegade Expert.
Can't seem to find any clear answers anywhere, hoping some here has some insight!
I have no experience with the GRX but I remember reading the same thing that you wrote; they added 2.5mm outward offset to the crank which was accounted for with the new FD. My guess is the shifting would move the FD the same distance, but you might run out of adjustment with the limit screws.
I have the GRX 46-30 crank and 105 shifters. It will shift to the big ring with careful adjustment 6but the trim adjustment is useless. GRX front derailleur is in my future. Just don't get the 2.5 mm further outboard thing. Now I have smaller big ring but chainline is AFU. I do like the 30. Let's me use a 11-36 cassette instead of a 11-40 and a derailleur hanger extender. Just wondering if Shimano has some sort of wider rear standard planned to move the cassette over 2.5mm to match.
Nebo wrote:I have the GRX 46-30 crank and 105 shifters. It will shift to the big ring with careful adjustment 6but the trim adjustment is useless. GRX front derailleur is in my future. Just don't get the 2.5 mm further outboard thing. Now I have smaller big ring but chainline is AFU. I do like the 30. Let's me use a 11-36 cassette instead of a 11-40 and a derailleur hanger extender. Just wondering if Shimano has some sort of wider rear standard planned to move the cassette over 2.5mm to match.
I call bs on this. Grx isn’t even out yet. How did you get it and where did you get the chainrings? Post pics of your bike.
I call bs on this. Grx isn’t even out yet. How did you get it and where did you get the chainrings? Post pics of your bike.
I see the grx cranks available to ship from a lot of places. Not all parts of this groupset are available yet but this is one of them.
Nebo wrote:I have the GRX 46-30 crank and 105 shifters. It will shift to the big ring with careful adjustment 6but the trim adjustment is useless. GRX front derailleur is in my future. Just don't get the 2.5 mm further outboard thing. Now I have smaller big ring but chainline is AFU. I do like the 30. Let's me use a 11-36 cassette instead of a 11-40 and a derailleur hanger extender. Just wondering if Shimano has some sort of wider rear standard planned to move the cassette over 2.5mm to match.
Was the only issue with the front derailleur, or the rear as well?
Yes, everything in the rear is good. I use a 105 mid cage rear derailleur and a SRAM 36t cassette with the b screw maxed out(all the way in). Front is shifting good enough for now. I see that US suppliers have GRX 810 front derailleurs in stock now. 50+ dollars plus the cost of a braze on adapter. I probably should have waited for the lighter 810 crankset but I wanted that 30t inner badly.
The GRX stuff look great, but it is a specific to itself range - when you start to mix and match with other components looks like you might get grief. Anyone wanting a 46/30 48/32 etc crank without the need to change out various other parts (i.e. so you can keep you 105 parts etc) to get it to work slick could look at FSA SL-K adventure range. I've fitted a 46/30 to my Cannondale Slate and have never looked back. The 386evo system is compatible with most BBs - even the less commons BB30A on a Slate. Available in Carbon (expensive) or Aluminium (good value vs weight)
Schadenfreude wrote: Anyone wanting a 46/30 48/32 etc crank without the need to change out various other parts (i.e. so you can keep you 105 parts etc) to get it to work slick could look at FSA SL-K adventure range.
Was looking at this as well - do you know if it can be converted to 1x? I think the fitting FSA 1x rings only go up to 36 or 38 (MTB?)
I'm at 50/34 with a 11-34, so starting off with slightly lower gearing than OP, but looking to also achieve some lower gearing on the gravel bike.
FSA SL-K Modular 46/30 is about $350-400, which seems to be more expensive than the GRX solutions.
Could go with OP's original inquiry of the GRX FC-RX600-11 46/30 crankset, which is $150 plus the FD-RX810-F $52 (to solve the above problems), comes out to be $150 cheaper than the FSA solution.
Talking to my local bike shop, they've been changing out a lot of 105 R7000 cassettes to a 11-40, without needing a roadlink. But, I've seen mentions of this causing some slow shifting into the largest cog. Alternative could be the new GRX rear derailleur ($112) plus a 11-40 or 11-42 cassette ($100) with the original 50/34 crankset. It seems it will be able to manage more chain than the 105 R7000 RD, even though they have the same listed max cog size.
FSA also a cheaper 46/30 and 48/32 option called the "FSA Omega Adventure". Mind you this would work with Shimano road derailleur, but needs a 19mm spindle bottom bracket.
If I was already running Shimano 11 speed with a 50/34, I would be inclined to swap the 50 for a 46 and go with an 11-40 cassette as an alternative to a GRX crankset with an 11-34. The advantages I see are: a) gets you a slightly lower lowest gear b) no change to Q factor or chainline c) 12T diff in rings mitigates need for rear shifting to recover gear when shifting front
Involuntarysoul wrote:moving the crank out 2.5mm without re-dishing the rear hub, wouldn't that complete change the chainline for the worst?
I thought this too, but maybe drwelby is right? (quote below) I would think this would mean that with my current 105 cranks, my chain line is eff'd up right now with my 142mm rear spacing? I'd like him to be right so I can just order up the grx cranks and front derailleur and be good to go.
drwelby wrote:
This is basically catching the cranks up with the move from the old 130 QR spacing to disc brake 135/142.
drwelby is correct. However, for me, I like the chainline as is with my 135/142 rear. I tend to use the upper 2/3 or so of my cassette way more frequently than the lower 1/3, and rarely use the smallest cog. So, for most of the time, keeping chainline as is results in less chain deflection on the cogs I use most frequently than I'd get with moving it outboard by 2.5mm (i.e. with GRX crank). Granted, the efficiency improvement is totally marginal and I'd likely never notice it if I switched, but the geek in me recognizes it and it would kind of bug me knowing I'm less efficient, however insignificant.
Just looking to see if anyone is running a 46/30 GRX with a 105 front der. Tech docs for GRX mention that there's a 2.5mm offset that needs to be accounted for (thus "justifying" a new GRX front der) or can you get away with it?
I just measured the front chainline of my stock crank (FSA Omega 46/30) on my Topstone 105. Did measure multiple times...constantly getting around 46/47mm chainline - several websites list a 43.5mm chainline for this crank?!?! no info on the FSA website...does anybody know more? If my measurements are correct - GRX should work with a 105 front derailleur (I have a 105 r7000). Thinking of switching to 48/31 now, too. Is anybody using it already? The 17t jump scares me a bit...
I just measured the front chainline of my stock crank (FSA Omega 46/30) on my Topstone 105. Did measure multiple times...constantly getting around 46/47mm chainline - several websites list a 43.5mm chainline for this crank?!?! no info on the FSA website...
How did you measure the chainline? Doesn't strike me as something that is easily done reliably. bike24.com is typically well informed and they list the crank Q factor 146mm and chainline of 44mm. The crankset does come with one or two spacers if I remember correctly, to be installed non-drive side. Perhaps Cannondale installed the spacer on the drive side to improve tire clearance...?
Just looking to see if anyone is running a 46/30 GRX with a 105 front der.
I've been using the 46/30T GRX crankset with my Di2 Ultegra 6800 derailleurs.
Briefly, it works, but I had to adjust the H-limit screw to its most extreme outboard position. There was less than 1mm to spare. I have a band-clamp on a straight-gage steel seat tube, so I have the luxury of positioning the derailleur wherever I want it. It was cutting it quite close, so what I recommend is that you first check to make sure that you have about 4mm of H-limit wiggle-room before you try this. (If not, the GRX front derailleur should solve your problem).
I first had a Shimano Ultegra 50/34T crankset that came with the bike, and then had a White Industries 46/30T square taper crankset. I find the comparatively inexpensive Shimano GRX option to be smoother-shifting than the White Industries crank, and the BB is much less frustrating.
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