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Could I use a 52/34 chain set combination? For context - it would be 105 5800

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VeloUSA [283 posts] 4 weeks ago
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Not a sold idea.  The issue I experienced is going from small to big the ramps would not always catch the chain.

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Joe Totale [123 posts] 3 weeks ago
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Given that a 16 tooth shift from big to small chainring on a standard crankset can be pretty jarring in terms of cadance a 18 tooth shift is only going to feel worse.

 

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kil0ran [1291 posts] 3 weeks ago
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It will work, but it won't be reliable or pleasant. Pretty sure I saw photos of some of the pros with this setup on the '17 Vuelta for that insane section with the concrete 20%+ ramps

Shimano's recommended maximum difference is 16 teeth so it's not too far out spec. Might need some serious cable tension and a perfectly-aligned front mech to get it shifting reliably. Will also need good shift technique.

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Pilot Pete [100 posts] 3 weeks ago
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It’s all very well saying it won’t work, will inevitably be jarring, won’t be pleasant, will be unreliable etc etc, but have all those commenting actually tried it? VeloUSA obviously has and didn’t get his to work cleanly.

Ive got a Rotor 3d+ crank with ‘no q’ (round rings) in 52/34 with Shimano Dura Ace di2. It shifts flawlessly. No jarring, no scraping, no clunking, no miss-shifts, no dropped chain, it just shifts exactly as it did when I was running it 52/36.

Perhaps that is the power of a di2 front shift which is so positive making it work.

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VeloUSA [283 posts] 3 weeks ago
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"Perhaps that is the power of a di2 front shift which is so positive making it work."

I'm on Di2 with DA FC-R9100 crankset/chainset. I need to find out if Shimano and Rotor ramp pitch angles and/or lengths vary.

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kil0ran [1291 posts] 3 weeks ago
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Pilot Pete wrote:

It’s all very well saying it won’t work, will inevitably be jarring, won’t be pleasant, will be unreliable etc etc, but have all those commenting actually tried it? VeloUSA obviously has and didn’t get his to work cleanly.

Ive got a Rotor 3d+ crank with ‘no q’ (round rings) in 52/34 with Shimano Dura Ace di2. It shifts flawlessly. No jarring, no scraping, no clunking, no miss-shifts, no dropped chain, it just shifts exactly as it did when I was running it 52/36.

Perhaps that is the power of a di2 front shift which is so positive making it work.

The precision and ease of a Di2 front shift is the only reason I'd go back to electronic - and I think you're on to something in that the chain basically has no choice when it's shoved by a Di2 front mech. I guess the only risk is it not reaching the ramp and then jamming/destroying the mech.

With a cable mech you as a rider need to be able to throw the lever hard enough to shift back up to the big ring, and maintain that pressure, possibly with a bit of overshift, and potentially in horrible crossed combinations. Factor in cold/wet hands and a tired rider and I think you'll end up with unreliable shifting. In my experience it's easy enough to fluff an upshift on a CX crankset (46/36) when knackered and that will require much less effort than an 18 tooth difference.

The other thing to perhaps factor in is changing the rear mech at the same time to one of new clutched road mechs to better control the chain in a front downshift.

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Pilot Pete [100 posts] 3 weeks ago
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But like I said, I’ve never experienced any problems shifting up or down with that combination. It’s as smooth as it was with 52/36. So in my opinion, certainly with my combination of components, it is very doable.

PP

oh and p.s. in response to Kiloran’s post, as you can see, they were using 53/34 and that seemed to work! They went for a 32 rear cassette which necessitated a long cage rear derailleur (Ultegra). I’ve stuck with a 28 on a short cage Dura Ace. I’ve read somewhere that you can fit the longer cage onto a Dura Ace rear mech which would save you buying another Ultegra di2 rear mech.

Of course the latest DA 9150/70 has a longer cage, I have that on another bike, but the one in question is 9070.

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kil0ran [1291 posts] 3 weeks ago
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Here's the story on the 53/34 setups used by some teams on Los Machucos

https://www.cyclingweekly.com/news/racing/vuelta-a-espana/vuelta-riders-...

But yes - these are Di2 setups.

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Canyon48 [1121 posts] 3 weeks ago
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I've had absolutely no issues mixing and matching chainrings however that was swapping a 50/34 for a 50/36, so reducing the teeth difference.

Shimano tend to be very conservative with their recommendations, so I don't think 52/34  wouldn't work, but the jump would be relatively massive between the two chainrings - so I can't imagine it'd feel great.

If you want a larger range of gears, Shimano's new R7000/8000/9100 gives you the ability to use an 11-34 cassette, so you don't need to have a great big jump between your front chainrings.

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Pilot Pete [100 posts] 3 weeks ago
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“so I can't imagine it'd feel great.”

Well, if you read the previous posts, in my experience it is no different to 52/36, which I had fitted previously and have on another bike. It is as smooth, with no mis-shifts, chain drops, or anything else you can think of.

PP

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Joe Totale [123 posts] 3 weeks ago
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Pilot Pete wrote:

“so I can't imagine it'd feel great.”

Well, if you read the previous posts, in my experience it is no different to 52/36, which I had fitted previously and have on another bike. It is as smooth, with no mis-shifts, chain drops, or anything else you can think of.

PP

Well the original poster will be using 105 5800, not Dura Ace Di2 with Q rings, I'm not sure how comparable the two are. 

Also I'm not talking about mis-shifts or chain drops but the huge change in cadance that will happen when you do an 18 tooth shift. 

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srchar [1168 posts] 3 weeks ago
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Ran 52/34 on Chorus in the Alps. Worked fine. If you're in the mountains ( the only reason I can think of for wanting to run a big/small chaining combination), you only shift rings at the bottom and the top anyway. I've done rides with 5000m of elevation gain and shifted rings fewer than ten times.

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Duncann [1485 posts] 3 weeks ago
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Interesting question.. I blithely told a friend it would be fine, although I don't know if he ever implemented it and I've never tried it (although IIRC the old Campag front mech on my 34/50 is actually meant for 39/53 and it's OK despite jumping two teeth too many...)

Looking elsewhere online, there seems to be a difference between those who say it won't work because it's not supposed to, and those who say they've done it and it's fine (although they don't always say if they're using electronic shifting).

https://weightweenies.starbike.com/forum/viewtopic.php?t=145943

www.bikeradar.com/forums/viewtopic.php?t=12909813

https://forums.roadbikereview.com/components-wrenching/shimano-ultegra-5...

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Pilot Pete [100 posts] 3 weeks ago
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Joe Totale wrote:
Pilot Pete wrote:

“so I can't imagine it'd feel great.”

Well, if you read the previous posts, in my experience it is no different to 52/36, which I had fitted previously and have on another bike. It is as smooth, with no mis-shifts, chain drops, or anything else you can think of.

PP

Well the original poster will be using 105 5800, not Dura Ace Di2 with Q rings, I'm not sure how comparable the two are. 

Also I'm not talking about mis-shifts or chain drops but the huge change in cadance that will happen when you do an 18 tooth shift. 

Im not using q rings. The ‘huge’ change is cadence is irrelevant. The whole reason from going from the 52 to the 34 is because the road is about to go up steeply. So I change into a suitable gear before I hit the big gradient change. I then match my cadence to my climbing speed.

Over the top of a hill my speed is about to increase significantly so I change up to the big ring. I then ride my preferred cadence on the downs. Don’t try to find reasons that don’t exist to say something ‘won’t work’ or ‘won’t be ideal’.

I have openly admitted tha I am using di2 and maybe that is why it works. I don’t know if it would work with 105, but for the cost of a chainring the Op could find out...

https://www.bike-components.de/en/Shimano/FC-5800-105-11-speed-Chainring... less than €10...

PP

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fukawitribe [2671 posts] 3 weeks ago
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Canyon48 wrote:

I've had absolutely no issues mixing and matching chainrings however that was swapping a 50/34 for a 50/36, so reducing the teeth difference.

Shimano tend to be very conservative with their recommendations, so I don't think 52/34  wouldn't work, but the jump would be relatively massive between the two chainrings - so I can't imagine it'd feel great.

If you want a larger range of gears, Shimano's new R7000/8000/9100 gives you the ability to use an 11-34 cassette, so you don't need to have a great big jump between your front chainrings.

TBH i'm struggling to think of any remotely recent Shimano mid-cage rear mech that wouldn't cope with an 11-34, 10- or 11-speed. I've also been running one with an RD-6800 GS for over a year and it's been flawless, and without any adjustment, e.g. B-screw, apart from a new chain as the old one was knackered (added 2-links over the one set-up for 11-28/32, but looking at the angles i'm not sure it was entirely necessary).