Can you do a Shimano 52/34 with a 11/28?

[sworcester]

I am building a new bike and put what was a 52/36 on the bike but a 34 inner. I put the chain on the 52-28 and with the RD at 90 degrees, put the pin in. In the 11-34 theres a huge amount of chain on the bottom not tensioned so it seems it can't be done.
Is it possible? I do have 36 rings on order, but they might be a long time coming since they are back ordered.

[weisan]

Sword pal, I have done this on several of my bikes. 52/34 front, 11-34 back. I use a long cage mtb derail. With proper adjustment and chain length, the shifting is flawless.

Your question is : can it be done?
NOT: "why would anyone want to do something like that?"

And my answer is: yes it can be done without any issue.

[Ralph]

You can't do it with a short cage RD (well you can if you either don't use all the little cogs with the small ring, or shorten the chain so it won't shift the largest couple cogs on big chainring.....not a recommended way to set it up). Maybe with a med cage, and for shure with a long cage as noted above.

[oldpotatoe]

I am building a new bike and put what was a 52/36 on the bike but a 34 inner. I put the chain on the 52-28 and with the RD at 90 degrees, put the pin in. In the 11-34 theres a huge amount of chain on the bottom not tensioned so it seems it can't be done.
Is it possible? I do have 36 rings on order, but they might be a long time coming since they are back ordered.

Sure just measure small/small. Chain as you measured too long. Ideally the rear der pulleys, a line thru them should be perpendicular to the ground when in highest gear. But small-small, length just when rear der cage spring starting to unwind. About 3mm from chain to rear der body.

[Waldo]

Greedy. In a good way. I hope it works.


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[spartanKid]

You can't do it with a short cage RD (well you can if you either don't use all the little cogs with the small ring, or shorten the chain so it won't shift the largest couple cogs on big chainring.....not a recommended way to set it up). Maybe with a med cage, and for shure with a long cage as noted above.

Definitely this. Do you know what kind of RD you're using? A long cage 6700 RD (RD-6700 GS) has a total capacity of 39 T, the short cage version (RD-6700 SS) has a capacity of 33 T.

The long cage is used for triples, which one could imagine being something like: (52-30) + (28 - 11) = 22 + 17 = 39 T.

Now you're suggesting (52-34) + (28 - 11) = 18 + 17 = 35 T. This means a SS won't do it (2 teeth short) but a GS should happily take up enough slack.

Now the question is, what does a 52-34 shift like?! :eek:

[weisan]

Now the question is, what does a 52-34 shift like?! :eek:

This is where the true masters reveals themselves, if done right, it's smooth and allows you to stay in the big ring 85-90% of the time. :banana:

[oldpotatoe]

Definitely this. Do you know what kind of RD you're using? A long cage 6700 RD (RD-6700 GS) has a total capacity of 39 T, the short cage version (RD-6700 SS) has a capacity of 33 T.

The long cage is used for triples, which one could imagine being something like: (52-30) + (28 - 11) = 22 + 17 = 39 T.

Now you're suggesting (52-34) + (28 - 11) = 18 + 17 = 35 T. This means a SS won't do it (2 teeth short) but a GS should happily take up enough slack.

Now the question is, what does a 52-34 shift like?! :eek:

These 'numbers' need to be taken with a HUGE grain(lump) of salt. When shimano made only a 12-27, they said 27t was MAX, then they made a 11-28..28t now MAX! Now 12-30..same derailleur. Same for front der and compact. 14t max difference, until compact, same der, 16t now max.

A 52/34 and 11-28, probably, with proper chain length(just long enough for big-big combo) will work fine. As I mentioned, a mid compact(52/36) and 11-28-no problema..52/34-11/28 probably will to.

If shifted with a little shifting finesse..pressure off the pedals when shifting, should shift fine, 34 to 52.

[ergott]

I've always measured chains from small cog to small ring. Then, remove enough links so the chain exits the lower jockey and continues uninterrupted to the crank.

[Ralph]

I've always measured chains from small cog to small ring. Then, remove enough links so the chain exits the lower jockey and continues uninterrupted to the crank.

The issue with doing this with a short cage RD and 34-52 and 11-28 is.....when you cut the chain for proper small to small (or even kinda slack for small to small).....it won't wrap up the big to big....without breaking something. That's 35 teeth difference. Med cage will. For sure a long cage will.

My question w/b....with a 11 tooth cog in rear....why the need for a 52? A 50 to a 11 is a huge gear. And a 34-50 and 11-28 will work with a short cage. Shucks....a 50X12 is a big gear (112").

[sworcester]

The issue with doing this with a short cage RD and 34-52 and 11-28 is.....when you cut the chain for proper small to small (or even kinda slack for small to small).....it won't wrap up the big to big....without breaking something. That's 35 teeth difference. Med cage will. For sure a long cage will.

My question w/b....with a 11 tooth cog in rear....why the need for a 52? A 50 to a 11 is a huge gear. And a 34-50 and 11-28 will work with a short cage. Shucks....a 50X12 is a big gear (112").

It is a short cage Di2 6870.

The 34/52 comes from swapping the inner ring from a 34/50 that I wanted a 36 on the inner and took it off of this bikes 36/52 crank. I have 36T inners on order, but they are on backorder. Two of the bikes will end up as 36/52 and one as a 36/50.
As far as 11 tooth, I have 3 cassettes on 3 different sets of wheels, an 11-23, 11-25, 11-28 and want to be able to swap the wheels around as needed (3 bikes too).
Was looking for versatility.

[mg2ride]

Sword pal, I have done this on several of my bikes. 52/34 front, 11-34 back. I use a long cage mtb derail. With proper adjustment and chain length, the shifting is flawless.

Your question is : can it be done?
NOT: "why would anyone want to do something like that?"

And my answer is: yes it can be done without any issue.

What he said.

Some of the long cage MTB derailers have the opposite preload direction so it can make shifting opposite of what is the norm. Still works but weird. Just be aware of that going in.

[Ralph]

It is a short cage Di2 6870.

The 34/52 comes from swapping the inner ring from a 34/50 that I wanted a 36 on the inner and took it off of this bikes 36/52 crank. I have 36T inners on order, but they are on backorder. Two of the bikes will end up as 36/52 and one as a 36/50.
As far as 11 tooth, I have 3 cassettes on 3 different sets of wheels, an 11-23, 11-25, 11-28 and want to be able to swap the wheels around as needed (3 bikes too).
Was looking for versatility.

Here is how I would do it.....if you are going to use a small cage RD.....especially if it's temporary with a larger small ring on order. Set it up with the small to small too slack. or maybe OK when the chain is on 34 in front, and second or third cog in rear (from smallest one).....simulating when you get the larger front chainring. Running it too slack on small to small won't hurt anything, since you don't use that combination anyway. It's important to use enough chain to wrap the big to big....should you accidently shift to that without meaning to. Then when the 36 comes in, just put in on....you probably won't need to make changes to chain.