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Banned Sock Puppet
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Searched the internet to see if I could get the drive side spider and non drive side arm separately, but it was by far easier (and cheaper) to get a complete set (chainrings and cranks)
Yeah, I see lots of 5800 non-drive side crank arms on eBay for $50-60. The correct drive side spiders are much harder to find.
 

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Discussion Starter · #42 · (Edited)
Yeah, I see lots of 5800 non-drive side crank arms on eBay for $50-60. The correct drive side spiders are much harder to find.
I figure that in the big scheme of things, a $240 US ($320 AUS) crankset that you can resell for $150 if it doesn't suit, is bugger all when you consider how much we "happily" drop on a new bike or wheelset.
 

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I figure that in the big scheme of things, a $240 US ($320 AUS) crankset that you can resell for $150 if it doesn't suit, is bugger all when you consider how much we "happily" drop on a new bike or wheelset.
Were you able to find the exact same crankset with shorter arms? If not, did you notice any difference in front shifting?
 

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Yep, I went from 52-36 @ 175 to 52-36 @ 172.5, so I didn't have to adjust anything. Stock was limited here in Aus for a while, but came good.
Same generation?
 

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I wouldn't recommend raising your seat to simulate shorter cranks, your hamstrings will suffer.
Yes, this would be trading one problem for another. But I don't think that was being discussed. Some were suggesting raising the saddle AFTER getting shorter crank arms which I think is changing too many variables at a time anyway.
 

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Yes R8000.
I have 5800 and 6800, but those are impossible to find anymore. I would need to go to 7000 or 8000. As long as they are Hollowtech II, I presume they should work.
 

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Discussion Starter · #50 ·
I have 5800 and 6800, but those are impossible to find anymore. I would need to go to 7000 or 8000. As long as they are Hollowtech II, I presume they should work.
I really like the 8000. Probably the best (and last) mechanical Ultegra. Although a crankset will always be mechanical!
 

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I really like the 8000. Probably the best (and last) mechanical Ultegra. Although a crankset will always be mechanical!
How are the 8000 and 6800 cranksets different other than aesthetics? They're both 11 speed, correct?
 

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I went the other way, from 172.5 to 175. I was changing cranks on an older bike and I wanted to match the crank arm length on my other bikes, which both had 175 cranks.
I, also, did not notice a difference in feel, but I did see a slower cadence.

That was it. No change to saddle height, no difference in speed (of course, when you upgrade a bike you always "feel" faster, but it is rarely borne out by actual results), no difference in recovery. When pedaling the longer cranks I had a lower cadence by a few rpm (3 - 5 rpm, maybe) that I couldn't feel but could see when I checked my cyclecomputer.
 

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You're gonna buy those cranks after all the debonding and corrosion failures? 105 is cheaper and better.
Debonding and corrosion failures? Are you talking specifically about 8000 or are you talking about Ultegra before that? I have over 10K miles on a 6800 Ultegra crankset and never had any debonding or corrisions issues.

That being said, I can't see any reason to spend over $100 more to buy the 8000 over the 7000 when all you save is 39g. I don't know anything about either of those first hand. I do have bikes with both 6800 and 5800 and they both shift flawlessly.
 

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So my old brain cells finally kicked in and recalled that I had an old FSA Gossamer Crankset in my tickle trunk , turns out it is a compact with 170mm arms . Then I had a look at my oldest daughters bike which she rarely rides and it also has Gossamer cranks with 165mm arms .
So I just ordered some cheap adapters as my older road bike has a 386 bottom bracket , these adapters will reduce it down to the 24mm spindle and the experiment will be underway with minimal cost. May take some time but I will give an update down the road .
 

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So my old brain cells finally kicked in and recalled that I had an old FSA Gossamer Crankset in my tickle trunk , turns out it is a compact with 170mm arms . Then I had a look at my oldest daughters bike which she rarely rides and it also has Gossamer cranks with 165mm arms .
So I just ordered some cheap adapters as my older road bike has a 386 bottom bracket , these adapters will reduce it down to the 24mm spindle and the experiment will be underway with minimal cost. May take some time but I will give an update down the road .
Ut's a wonderful thing when a plan comes together. (y)
 

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Discussion Starter · #58 · (Edited)
So my old brain cells finally kicked in and recalled that I had an old FSA Gossamer Crankset in my tickle trunk , turns out it is a compact with 170mm arms . Then I had a look at my oldest daughters bike which she rarely rides and it also has Gossamer cranks with 165mm arms .
So I just ordered some cheap adapters as my older road bike has a 386 bottom bracket , these adapters will reduce it down to the 24mm spindle and the experiment will be underway with minimal cost. May take some time but I will give an update down the road .
Good find!. Be interested to see how your change goes. Yeah, Shimano had the debonding issue, but I am pretty sure they sorted it. As much it would suck to be one of the few people who had an issue (hopefully no injuries), I guess out of the thousands of cranksets produced it would be a very small percentage that had an issue.
 

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Good find!. Be interested to see how your change goes. Yeah, Shimano had the debonding issue, but I am pretty sure they sorted it.
Doing a search, the debonding issue was on 6800 and 9000 cranksets. Apparently 105 is one machined piece whereas Ultegra and Dura-Ace bond two pieces together and that design somehow saves weight. Not sure if the newer generations are the same way.

Keep in mind if you search the internet hard enough, you will find examples of failures for SRAM and Campagnolo as well as Shimano.
 

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Gidday guys.

I have been riding 175mm cranks all my life. The first bike I bought had them, and not knowing any better, any other bike I bought had them, and bike shops just said "you are 6'1", it's what you need". Any groupset I bought had them, because it's what I though I needed.
Now that I am getting older, I am finding my knees are getting sore after a ride, so started researching via the good old internet and questioning if they were the right length.
With a 860mm inseam, all the research I did indicated 172.5 was the optimum length for me, so I took the plunge and got a set of Ultegra R8000, 52-36 in 172.5.
I really wasn't expecting to feel any difference with a change of only 2.5mm, and really thought I had just wasted my money, but wanted to give it a try.
Well, I was pleasantly surprised. As well as my knees feeling a lot better, it just felt smoother. My 175's didn't feel bad to turn in any way, but the 172.5's just feel smoother turning them.
Anyway, I know it's very subjective, and there are multiple formulas and opinions, and what worked for me, may not work for others, but just sharing my experience.

I wasn't expecting any noticeable difference, but I am glad I was willing to spend a relatively small amount of money to be a lot more comfortable on my bike. I didn't make any other setup changes.

Regards to all.
2.5 mm is a tiny change in crank length. Its like a 1.5% change. The sole thickness on different shoes probably differs by a lot more than that. I think its all in your head.
 
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