Natenat138

I've been able to find the rare and elusive Cannondale Topstone at my LBS, and in my size to boot! But it's the base model while I've had my eyes on the 105, and the shop says Cannondale won't have any more 'til March, if they even have any at all.
Checking the specs between the two, they seem like almost the exact same bike aside from the groupset and wheelset. Am I missing anything obvious?

Just checking to see if anyone here has one, has ridden it enough to make a good review of it, and would/wouldn't recommend buying the base model and upgrading the groupset (really just the shifters, freehub body, rear cassette, front & rear derailleurs).

DanBell

It's certainly doable, but I think Shimano is actually in short supply of their road hydro disc groupsets right now as well. I had a look online the other day and I could not find complete 105 R7000 disc groupsets anywhere (if anyone knows where to find these, let me know). Other than that hurdle, the frame is the same, so there's no reason why you couldn't do this. If you pull the Tiagra group off straight away you can sell it on as a 'like-new' groupset to recoup some of your cost for the upgrade, or keep it around for building more of a rainy weather/beater bike.

Natenat138

I don't necessarily need to do hyrdo, I'm fine with a mechanical 105. And the groupset on the base model is their new (?) Sora, which is a 2x9 set...woof.

DanBell

Oh right, forgot it was Sora. The caliper version 105 R700 groupset is widely available and quite reasonably priced. I don't know if the levers pull the right amount of cable to work with the mechanical disc brakes that come with the bike though.

Spoonrobot 

There's no sense in buying a bike to replace all those parts. Buy a different bike and take advantage of OEM savings the company gets versus buying the upgrades at street price and doing the labor yourself - the former is the way to do it.

New 2x9 Sora is pretty amazing, same with newer Tiagra. No difference between them and 105 other than weight.

shoota 

Unless he really wants the Topstone. Like he said they aren't exactly easy to find. If it were me I'd buy it, upgrade to whatever I wanted (usually a really nice used group from the various places to buy that kind of thing), and then sell the Sora stuff.

OP: I'm 99.9% sure there is no difference in the frames between the models.

Koyote

Test ride any Topstone to make sure you have found the right size, and then find a C'dale dealer to order the exact model you want. If you're willing to plunk down your money, they might be able to find one.

It does look like a nice bike, by the way.

Spoonrobot 

Where are you at? REI has 105 online but it's ship to store only. Few years ago I mocked up something similar for what you want to do including expected resell prices for new-takeoff groupset and it was cheaper for the customer to make a 10 hour round trip drive to pick up the model he wanted rather than; order the lower end model, groupset from Wiggle, do the install and then resell.

https://www.rei.com/product/145825/c...-105-bike-2019

My LBS, which I never use for anything, says they can order a medium 105 and have it here within 2 weeks.

mstateglfr 

it's 9 instead of 11 cogs and something like half a water bottle heavier. Besides that, new Sora is really nice.

We all want what we want, and I would want 105 to be fair, but 'woof' just seemed misplaced based on the quality.

Spoonrobot 

Few have ridden Claris, Soma or Tiagra enough to form an opinion. Instead it's regurgitating party line and dutifully avoiding confrontation of the fact that there's no repeatable, objective metric to judge a given groupset. Instead we see weight and price used to declare something junk or best thing ever.

In this day and age where it's not only possible but cheap and easy to measure such things as shift lever/derailleur actuation speed or torque per lever or shifter cable friction or relationship between shift lever torque and relative chain lubricity or any number of variables that make up the feel and performance of a group, almost no objective information is shared for a given groupset. It's weight, and it's price. And if it's not those two, it's internally branded measurements or improvements that can't be evaluated against a competitor.

Imagine seeing a test for 105 that listed the average speed for a 3 cog up shift of down shift compared to Sora or SRAM or Microshift. That would be amazing. Or plotted the shift speed over the life of cable/housing for 10,000 shifts.