squirtdad

My last build I went with full r8000 ultegra mechanical, but swapped out the brakes for Velo Orange grand cru to allow for more than 28mm tire clearance....

as there are not enough bike pics in this forum, here is how it looks

datlas 

Here is my build with Ultegra R8000 and Psimet wheels:

Jughed

But in this case, we have history - Ultegra/Dura cranks have been failing enough for websites to be started and youtubers making videos on the subject - calling out Shimano to step up and fix the issue. This indicates a problem with design/construction, and failures occur at a higher than normal rate. This is more than 1 off failures, and these are high dollar items.

Multiple composite experts have created decent videos about the cause of the failures - and its a clear design flaw.

Where the same generation 105 cranks don't have this problem.

For me, the extra $$ for the cranks, and the zero to min performance gains you get from the 2oz weight savings - is absolutely not worth the money.

mtbikerjohn 

That is pretty much my drivetrain that I used when I built up my Ross. I used Grand Cru brakes because I needed mid reach on that frame..Pretty sold drivetrain combination..John

smd4

You're mistaken.

Iride01 

We have lots of history of solid cranks failing too. Some where poor quality control issues that could be corrected by better manufacturing methods and the manufacturers did so. Some where design flaws and couldn't be corrected.

For y'all to be saying it's a design flaw is a little early I think. Proper glue bonds are strong enough whether you want to believe that or not. It might just be a occasional issue on the assembly line. And the number of confirmed failures is still extremely low.

PeteHski

The only R7000 105 component that I think is a bit dubious are the pedals with the plastic bearing housings. Having said that they still go the distance without causing any real world problems - just a tiny bit of play. But I do prefer DuraAce pedals because of this. Ultegra pedals are probably somewhere in between.

I think R7000 105 is hard to significantly improve on unless you go electronic. $300 is not an unreasonable upgrade cost for Ultegra, but mostly for badge honour. I can't see any practical difference and don't try to convince me that 174g weight saving makes any odds. Shimano/SRAM/Campag have done very well to cultivate these extreme diminishing returns on their higher level groups. Some people are more than happy to spend the cash for very little practical return and mainly for the cache of Ultegra and especially DuraAce on a high end bike. That's not a criticism, just a recognition that hobby purchases are not always rational.

Nachoman

Get the ultegra. Because YOU are worth owning the upgrade.

eljayski 

105 di2 offers widest gear range also, if that matters. (Where I ride it does matter.)

Germany_chris

I’m always in the low to mid level with shifters and derailleurs (2x Centaur, Rival, Tiagra) they shift as well as their better counterparts but don’t cost as much. I’m also not to big on groups as a whole so I use different makers for cranks and brakes.

if you’re going to keep the bike I can’t think of a good reason not to buy Ultegra.

datlas 

I am willing to be wrong. I do it all the time, ask my wife!

That said, I was looking for some type of proof or evidence whether "Hollowtech" refers to the hollow crankarms or the the hollow axle, and could not really find any. Maybe it's both??

smd4

It's both now. But it developed with hollow crankarms.

Emphasis added.

Shimano History

datlas 

Got it. Thanks.

georges1

Get the ultegra over the105, even though I would have prefered a mechnical ultegra, I am not fond of the new sti design nor the cranks design or the derailleur design. About reliability that must be seen over the very long term.

mstateglfr 

I am pretty sure that everyone who has had a bonded crank arm fail, and broke ribs or sliced skin or is scabbed over from slamming into pavement would argue that the failure rate should be 0.
Nobody that I have seen in pictures of the delaminated crank arms looks like they are crushing it with watts and a crankarm should be an incredibly strong and stiff part of the bike.

You claim its too early to say its a design flaw, then offer up an unsubstantiated guess that its a production flaw. Ok, regardless of where the flaw is occurring- it really shouldnt occur at all. Just make it(design and production) strong enough to not split apart in a catastrophic manner.

icemilkcoffee 

It's occuring way too often to be one-off failures. Look here:
https://www.instagram.com/thanksshimano/?hl=en
You can see pages and pages of pictures of these cranks breaking. Some people broke two in a row: https://carlinthecyclist.com/epic-fa...1-speed-crank/
Bikeradar has written about it and Hambini has a fairly comprehensive analysis of it as well.
This guy has six of these broken cranks:

Instagram

Must be 6 isolated incidents, right?
I can't understand how on this forum some people are scared to death of carbon assploding on them, and yet when faced with the very well documented and known failure mode on these cranksets, people could just bury their heads in the sand and think it's worth taking a chance on something that can fail and put your face in the dirt in an instance.

smd4

Agreed. I must say, I haven't seen too many Instagram posts or YouTube videos focused on the failure of my DA 7700 cranks...Or many others. This should definitely be of concern for people who run these afflicted cranksets.

georges1

This happened when shimano transitionned to four arms cranks with the Dura Ace 9000-9100 and Ultegra 6800/6870 -8000/8050, I don't know if the 105 5800-7000 is affected by this flaw. I am glad that I stick to Dura Ace 7700-7800 which have 5 arms crank and which don't have these problems. But at the price of what a high end group costs , it is a shame to see such manufacturing flaws happened. Remedy to this buy an earlier Ultegra 6600-6700 or an earlier Dura Ace 7800-7900 and you won't have those issues and are 5 arms cranks.Other possibility is to put a FSA or Vision crank

georges1

the da7700 and da 7800 never had failures unlike the latest ones. Maybe the manufacturing process hasbeen cheapened ?? The newer cranks doesn't seem to be forget but glued . That is why I stay away from anything new whether 11speed or 12 speed.

smd4

The 7700 at least were welded, and then polished to appear as one piece. Don't know about the 7800s. The cranks that have failed were glued together.

Iride01 

Well I'm not scared to death of carbon assploding. I ride a CF bike. And I'm not burying my head, but so far the issue hasn't gotten to the level that would force a recall or any safety advisory here in the USA. So until there gets to be a proven attempt by Shimano to cover up and ignore the issue, I'm not going to be bad mouthing Ultegra or DuraAce cranks. They seem to do well in the pro tours. I've seen chains break in the tours, but no cranks have broken. Even SRAM has some instances of their newer cranks breaking. But no one seems concerned with them.

Your pages and pages of pictures, many just more pics of the same crank don't really amount to anything but a teeny tiny fraction of all the Ultegra and DuraAce cranks out there today.

Sure, in a perfect world there should be no failures, but that ain't happening.

genejockey 

Once you get past 2, you're doing something out of the ordinary. If you get to 6, you're doing something intentional.

jadmt

yes that seems a little strange or actually a lot strange.

jadmt

for the record I went with the Ultegra thanks all who responded with input.

georges1

Here is a reviews about the dura ace 7800: dura ace 7800 The 7800 cranks weren't glued but forged