Dogtrousers
Lefty tighty. Get it righty.
I'm bringing forward my plan to replace my 105 50/34 chainset with a GRX 46/30. I was going to wait until the current chainset was well and truly worn out but I've become impatient.
The bike has 105 R7000 (11s) mechanical at the moment. I'd like to keep as much of that stuff as possible. Mainly to make the job easier. I intend to replace the cassette and chain at the same time so I make a new start with all new stuff.
The rear mech shouldn't be an issue capacity wise as the capacity is the same (50-34=16=46-30)
The bike is a steel framed bike and the front mech is band-on so I should be able to slip it down a few mm for the new smaller rings.
I may replace the RS500 bottom bracket while I'm at it because they don't last forever and the current one isn't a spring chicken.
This random website says it's all compatible https://www.cyclabo.com/topics/au0vhheojb/#compatibility-between-grx-and-road-105
But the Man from Spa Cycles says "a 105 front mech won't have quite enough throw to reach for the chainset, which sits 1.5mm further out."
Following the advice of the Man from Spa Cycles would mean fitting a new GRX front mech. As I can only find braze-on FD-RX810 in braze-on this would mean buying a separate clamp too. This all increases the amount of faff a lot and the expense a bit, but tbh expense is not the main concern. I can afford a new mech if I need it. It's more the faff that concerns me.
So my conundrum is: Do I believe the Man from Spa Cycles and get a new front mech? Or do I ignore him, cross my fingers, just get the chainset, then end up kicking myself when it doesn't work, order a mech have to wait while the new mech arrives, then find that the clamp is the wrong size or something like that, with my bike having been put out of action in the meantime?
Also, what the Man from Spa Cycles says worries me. If the chainrings sit 1.5mm further out, will that bugger up the shifting at the rear. It's tempting to ignore him and believe the random website, because I prefer its version of the truth, but it's a bit worrying.
As an aside, I could probably get a similar sized non-Shimano square taper chainset and fit a corresponding cartridge BB but that doesn't actually have any advantage that I can see and introduces a whole slew of new "will it work" and "what size BB" questions so I rejected that option as having more risk and no benefit. Case closed.
Anticipating the fact that CC posters tend to ignore specific questions and simply reply "you don't want to do that": Yes, I've done the gear ratio sums. Yes I do want to do that. No I don't want to fit an 8-speed triple, get a new bike, replace the chainrings individually, have my knees replaced, take up macramé instead of cycling or anything else like that.
The bike has 105 R7000 (11s) mechanical at the moment. I'd like to keep as much of that stuff as possible. Mainly to make the job easier. I intend to replace the cassette and chain at the same time so I make a new start with all new stuff.
The rear mech shouldn't be an issue capacity wise as the capacity is the same (50-34=16=46-30)
The bike is a steel framed bike and the front mech is band-on so I should be able to slip it down a few mm for the new smaller rings.
I may replace the RS500 bottom bracket while I'm at it because they don't last forever and the current one isn't a spring chicken.
This random website says it's all compatible https://www.cyclabo.com/topics/au0vhheojb/#compatibility-between-grx-and-road-105
But the Man from Spa Cycles says "a 105 front mech won't have quite enough throw to reach for the chainset, which sits 1.5mm further out."
Following the advice of the Man from Spa Cycles would mean fitting a new GRX front mech. As I can only find braze-on FD-RX810 in braze-on this would mean buying a separate clamp too. This all increases the amount of faff a lot and the expense a bit, but tbh expense is not the main concern. I can afford a new mech if I need it. It's more the faff that concerns me.
So my conundrum is: Do I believe the Man from Spa Cycles and get a new front mech? Or do I ignore him, cross my fingers, just get the chainset, then end up kicking myself when it doesn't work, order a mech have to wait while the new mech arrives, then find that the clamp is the wrong size or something like that, with my bike having been put out of action in the meantime?
Also, what the Man from Spa Cycles says worries me. If the chainrings sit 1.5mm further out, will that bugger up the shifting at the rear. It's tempting to ignore him and believe the random website, because I prefer its version of the truth, but it's a bit worrying.
As an aside, I could probably get a similar sized non-Shimano square taper chainset and fit a corresponding cartridge BB but that doesn't actually have any advantage that I can see and introduces a whole slew of new "will it work" and "what size BB" questions so I rejected that option as having more risk and no benefit. Case closed.
Anticipating the fact that CC posters tend to ignore specific questions and simply reply "you don't want to do that": Yes, I've done the gear ratio sums. Yes I do want to do that. No I don't want to fit an 8-speed triple, get a new bike, replace the chainrings individually, have my knees replaced, take up macramé instead of cycling or anything else like that.
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