Ballpark Costs of Midrange Shimano GXR Upgrade
 

I'm getting ready to pull the trigger on either a Cannondale Topstone 105 or Sora. I am BY NO MEANS knowledgeable about relative merits of various components, so I rely on the expertise of people in this forum. (and I sincerely thank you for the advice!)
I've been wondering about the advisability of buying the Topstone Sora for $1050 and then upgrading to a midrange Shimano GXR group when the GXR stuff becomes available. (assuming I would even want/need it down the road). Or do I just go with the highly regarded 105 groupo now? I confess that I do like the green color on the Sora equipped model.

As always, thanks for your help and advice.

Whoops! I forgot to ask for the estimated "ballpark" costs of a midrange GXR upgrade for the Topstone Sora. Sorry.

My guess - $900 for the full 105 level groupset with hydro brakes

What do you want from GRX that you aren't getting with 105?

Good question, Canker. What would an upgrade from 105 to GRX get you? I'm assuming that Shimano did something different with the GRX to make it attractive.

The primary difference is a crank (48/31T or 46/30T vs 50/34T). The brake pivot points are re-designed, and there are a few other tweaks. One of the rear derailleur options lets you use a bigger cassette.

If it were me, I would get the 105-equipped bike, and then only change the crankset and/or rear derailleur if necessary. (The chain-line will be +2.5mm, but I think the worst-case scenerio is that you might have to get a new front derailleur.) The Sora-level bike is likely to have other compromises. Also it is much easier to upgrade piecewise if you have 11-speed 105 to begin with.

Alternatively, wait (a year?) to get a bike already equipped with it. But keep in mind it will be more expensive because it is new.

Same here but I'd add you can already get a 48/32 or 46/30 chanrings from Absolute Black for your 105 crank now if you need the easier gearing. They aren't cheap but if you need em you need em and you don't have to wait. There is also the Roadlink option to make your standard RD fit a bigger cassette. I'm running the Absolute Black chainrings myself but may switch out to a GXR crankset for the 48/31 option when my current rings wear out depending on how much the crankset costs.

the pivot point is redesigned only in the di2 version. For mech, the brake lever shape is a little different and the hood rubber has more ridges that's about it

My plan is to wait till next year and see what the bikes are like that come with this group set. I expect they will be a little bit cooler. I’m hoping Salsa’s new model, the Warroad, will come with the 1X and a dropper.

And then since that will be too darn expensive, wait a little longer for a sale!

Buying a new bike with the intention of throwing all the drivetrain and brakes away in one season sounds CFCP to me

Good advice from all of you.

Not sure what CFCP means, so I looked it up. CFCP - California Farmland Conservancy Program?

I dunno, but it doesn't sound good.

throw that $$$ into a good bike rather than upgrading before you buy it.

105 FTW

Seems to me that GRX is trying to fill a void that's not there. I mean it's nice and all, but do we really need ANOTHER group?
Half the fun of putting a gravel bike together is frankenbiking the thing. I had Dura Ace, XT and 105 in the beginning. Still evolving (going Campy!).

I was guessing GRX would be in XT range plus a couple of hunski for the STI and hydros: $800?

OP - the bigger question is do you want to run tubeless? Because the Sora Topstone doesn't come with tubeless ready wheels or tires, the 105 does.

I run an 11-36 SRAM cassette with my 105 GS RD with zero issues. I put a Praxis Alba crankset (48/32) on my bike and I've got a hair under 1500 miles on it with zero issues. Granted I don't do a lot of riding in the muck but a whole lot of dust/dirt.

I've been happy with 26 gear inches on the low end with a range of about 491%

Granted an 11-34 paired to a 46/30 would be a touch lower 25.9 vs. 26.1 and some tighter spacing towards the bottom of the cassette, there's no frankenstein-ing to achieve these results with 105 and zero additional accessories.

Not to mention the tech is available right now and from my experience 105 is durable, reliable and most importantly readily available.

Get the 105 version and if you feel like you need smaller chainrings you can either go for the GRX crankset and front derailleur or absoluteblack chainrings. The Sora build of the Topstone has more compromises then just the drivetrain. Not beeing to setup the wheels tubeless would be a deal braker to me.

Yeah that bit of info kind of soured me to building out with GRX. I'm thinking GRX 1x crank, 105 hydro shifters (even though it's only a 1x up front) and sticking with the XT derailleur out back.

Tinkering is part of the fun...

Get the nicer bike and start riding. If any of the components are lacking, replace them later.

Get the 105 and don't look back. I have the new 105 7000 series stuff on both my Giant SLR2 gravel bike and Trek FX6S flat bar road bike and it's great. Shifts just as well if not better than prior bikes I owned with Ultegra or XTR.

Did you pull it?

I also was debating the same thing but my Giant Revolt came with 105 with a Praxis 48/32 crank and I can’t think of any reason why to switch to the GRX stuff since it has worked so brilliantly for me.

Coo-coo For Cocoa Puffs, I'm betting? I remember that commercial. No sugar in that breakfast cereal at all. :)

When I bought my Topstone I knew off the bat I wanted to 1x and loved the green that comes on the Sora tier. 400 bucks on wheels, 300 bucks on group, 50 for odds and ends. I have a 1x Rival group for less than the Apex tier, with better wheels and a smidge less in weight.

GRX is new and you won't find deals on eBay for a bit. I agree with everyone else saying to go 105 and upgrade as necessary. I got very lucky on the deals I could find, that lock will be scarce looking for GRX.

Pulled the trigger on this. Found a set of brand new 105 7000 hydro levers for less than half of retail (they were take offs from someone that thought they weren't good enough?) so my gain and I saved a crap ton of money too.

Finally going into the LBS to get the upgrade done. The OE calipers won't work with the 105 levers, so I'm also adding 105 calipers.
Also had to add a Wolf Tooth Tanpan so the 105 shifter would work with the XT rear derailleur.

Swapped out the shimmed SLX single ring with a GRX 800 single ring crank set. the Q-factor on the SLX was too wide to even shim correctly. So that slop is gone.

So yeah it's been an expensive undertaking. Good thing my wife doesn't know or care about how much I spend on bike components. 😁

as for the question in the OP

GRX 1x group $740 doesn't include crank
GRX 2x11 (braze on) $870 - $1050 all on Ebay from Taiwan

the Topstone is clamp fyi

the aluminum Topstone is already 46/30 11-34 sora being 9speed, and 105 being 11speed

the AB ovals are good for oval, but they are picky finicky shifting. and they COST a LOT!

IMO If he isn't racing then gear jump don't matter 9speed is good enough. if he likes the color then buy the SORA and invest in wheels. however sora is mech disc, and 105 is hydra.






really?