All,
Looking for another road bike, seen two options almost identical in build: the only difference is the groupset (c. £250 difference).
Apart from weight, is there any real difference between 105 and Ultegra?
I’ve had a look online, and there is a lot of conflicting information and entrenched views…
Cheers,
depends what road bike it is…
…I’d get Ultegra on a summer one and 105 on a winter bike.
I cannot tell the difference at all. My 11 speed winter 105 bike shifts and stops like a dream, as does my summer Ultegra.
I’ve seen a lot of comments that 105 with upgraded cables (dura ace) shifts as well as mechanical Ultegra/Dura Ace.
I think a lot of people will tell you that they cant tell the difference. My roadie is 105 and my TT Ultegra DI2. The TT seems to shift more precisely, but that has a carbon frame and everything feels more ridge and precise. My flex alu roadie feels like a bag of jelly most of the time. So it might feel better but I am not sure it is. My 105 roadie has been put through endless hours of punishment and reliability wise its been perfect, one snapped cable and a couple of snapped chains. I have heard the higher end stuff gives up some reliability or durability for weight, although thats probably more aimed at dura ace.
The main difference is the weight. If the weight is really important to you by ultegra, if not keep the 250 and buy yourself something nice.
This, DA cables are brilliant. On my old Shiv, the rear brakes weren’t great until I fitted DA brake cables and they were transformed. Ever since, I have fitted DA cables when time comes to change them
The difference between DA, Ultegra and 105. Brakes, the only difference is weight. Shift performance when new is very similar, I found that the barrel adjuster on the rear derraileur on the 105 is pretty weak. For shifting performance, when the chain wears out a DA chain is not much more expensive and shifts much better. DA cassettes last much longer, don’t think that there is a difference between Ultegra and 105 cassettes. 105 used to work with a wider range of gears, I think that Ultegra and 105 are now the same, but DA does not have the same range.
Pretty much this. You don’t really want 105 on a high-end frameset; do you? 
I have Ultegra on my Canyon Endurace SLX (top frameset) but didn’t see the value in spending way more on DA. Ultegra is pretty much the sweet-spot from an expenditure perspective.
Generally rear derailleur and cables can be particularly worth it, shifters a little, everything else not at all - but then I’m 10 years out of date so things might have changed. Things like crankset particularly not worth it.
Yes, exactly this.
For the price, the wearability for Dura Ace just doesn’t seem worth it.
Like @GRamsay said above, my personal opinion is that Dura Ace gives up some durability for performance (weight, mainly)
Ultegra and DA chains are like cheese these days and wear out if you so much as look at them 
Better off with a nice gold KMC chain 
I’ve never stumped up for DA, having only one chain and set of cranks, but I know my less used, mainly dry weather Ultegra cassettes wear much much faster than my wet weather, road grit grinded 105 cassettes.
I cannot tell the difference between my 105 and Ultegra direct mount rim brakes, but compared to the SRAM apex single mount ones, they’re a world ahead.
Is the weight really a factor though? LIke is it actually going to make a difference in the real world, or are you just as well eating one less weetabix in the morning before your race?!
YES! Damn it, what do you know 
Why the hell do you see TdF riders jettison’ing their Fly Elite bottles (weight about 54g) at the foot of climbs, then taking full bottles (~600g) at the top?
I didn’t see @apm’s name on the options list in my TdF fantasy team.
It’s another road bike - so i assume not his primary race rig.
My case stands.
ASSUME - Makes an ASS out of U and ME
If I was to buy another road bike, it’d be a super shiny one, to relegate my shiny one.
So I’d probably get a Giant TCR SL, just like Greg Van Avermaet’s, complete with RIM BRAKES (for the weight, as they’re lighter, innit)
I’d then have two bikes like Greg’s, although I bet he rides a Reynolds 725 steel winter bike, too.
Why do you think he’s microdosing EPO and swapping the 500ml bags out every few weeks?
I’m sure when GvA is faced with any given situation, he thinks “what would Teejaypeeps do?”
I think usually there isn’t much discernable difference between adjacent groupsets in the Shimano range, so 105 to Ultegra or Ultegra to DuraAce you would be hard pressed to tell the difference while riding, but if you skip 2 levels or more it is noticeable.
There’s also a big shift when they update iterations. The cheap bike I bought my gf during lockdown surprisingly had 105 shifters and mechs. It’s 5800 series. It’s significantly better than my 5700 series on my old road bike.
I’d used Ultegra on hired bikes abroad and it was noticeably better than my 105. Compared to the 105 on my gf’s bike, there now would be minimal difference. I only have di2 ultegra on my TT and new roadie, but other than being mechanical, the 5800 series shifts pretty crisply.
I think that one of the nicest shifting groupsets is the DA7900 or DA7800 10 speed, the 7800 especially where the cables come out of the side of the shifter (however, not aero and not a brilliant look). When they went to 11 speed shifting performance got worse
My old 10 speed ultegra was beautiful when setup and rarely went wrong. That bike lives on with my younger brother but I don’t think get’s as much use.
I’m not familiar with Shimano, as I mostly ride Campag but I have Ultegra on my TT bike and 105 on the Focus road bike that I keep at my Mum’s house.
I do all my own tuning and the TT bike shifts very smoothly and stays pretty spot on, even when moving from turbo to Zipp wheel.
Actual shifting, there isn’t a lot in it but the 105 is slightly more sluggish and needs a tweak more often (105 is newer but both are 11sp).
Braking wise, I can’t compare, as I have hydro rim brakes on the TT bike and disc on the road bike.
Cable, especially cheaper cables change length depending on temperature, the difference is very small, but can be enough to make a difference to shifting quality