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Hey guys, I am a formerly in shape biker that needs a new cassette. Back when I was in shape, I changed my cassette to an 11-25. Well now I would like to climb some hills again, and until I trim the extra tire that has formed around my waist hills are not going to happen. Can someone tell me what the largest cassette I can move up to with a Shimano 10sp rear derailleur? The bike came with a 12-28 Tiagra cassette, but I would like to move up to a 30 or 32 (if one exists). Thanks for the help.
 

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You didn't say which 10-speed rear derailleur you have. Is it a short or mid cage? Also a Tiagra? Do you have a triple or a double on the front? All these make a difference

If your RD is a mid-cage and you have a triple in front, you can go up to a 30T cassette.

If your RD is a mid-cage and you have a double in front, you can go up to a 32T cassette.

If your RD is a short-cage, then no-can-do. You will need to buy a mid-cage RD before you can go larger than a 28T cassette.
 

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It really depends on your bike (the hanger, maybe chain stay length). What shimano says is conservative and there's a good chance you can use bigger than they say.
It's a case of 'you won't know until you try' if you go over the specs.

Do you already have a compact crank? If not I'd suggest that because it won't become obsolete when/if you get in good shape like a 32 cog might. Cost a lot more off course though.
 

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Well, I'm sorry for my incomplete answer. I thought that a bike supplied with 12-28 would have mid cage... I certainly wasn't trying to mislead anyone.

50-34 compact, 11-32 10 speed, all Tiagra 4600, works.
 

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Both of you need to stop giving advice. You don't even know which derailleur the OP has, how in the hell can you tell him what cassette he can use? :idea:
never said it would work for him, simply showed that a 30T is available.

if you have to gripe, direct your comments at the OP for not supplying adequate info regarding his RD.

without details, it's up to him to figure out compatibility.
 

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His specific question was "what is the largest cassette his system can move to?". Not what cassettes are available. And in cx's defence (not that he needs any) if the op just slaps a 30 on and it's out of range for his Rd config, the damage when attempting to shift into the 30 could be significant.

Sent from my SM-G900W8 using Tapatalk
 

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His specific question was "what is the largest cassette his system can move to?". Not what cassettes are available. And in cx's defence (not that he needs any) if the op just slaps a 30 on and it's out of range for his Rd config, the damage when attempting to shift into the 30 could be significant.
Only if the chain is too short would there be significant damage. And I presume the OP would at the very least run the bike through all the gears before riding it. Or at least I hope so. If it binds in the large/large combo, he would find that out before he gets on the bike, rips the derailleur and stay off the bike and possibly injures himself.

That being said, even if the chain doesn't bind, if the derailleur isn't suited for such a large cassette gear, shifting will be clunky and the pulleys will clash against the gear teeth causing premature wear and a lot of noise. Turning the B-adjust screw all the way in may help a bit, but is really a Band-Aid on a broken leg approach.
 

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Only if the chain is too short would there be significant damage. And I presume the OP would at the very least run the bike through all the gears before riding it. Or at least I hope so. If it binds in the large/large combo, he would find that out before he gets on the bike and rips the derailleur and stay off the bike and possibly injures himself.

That being said, even if the chain doesn't bind, if the derailleur isn't suited for such a large cassette gear, shifting will be clunky and the pulleys will clash against the gear teeth causing premature wear and a lot of noise. Turning the B-adjust screw all the way in may help a bit, but is really a Band-Aid on a broken leg approach.
-Because damaging it on the work stand wouldn't be a problem?

-Wrong. If it works it works and depending on the overall picture there's a good chance it will.
 

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-Because damaging it on the work stand wouldn't be a problem?
Ummm, common sense says you would exercise care when shifting to that largest combo while in the stand - translate: SLOWLY. After shifting, turn the crank SLOWLY and don't turn against any resistance. Finding out if it binds is not rocket science.

I really didn't think I needed to explain this, but as I have stated before, maybe common sense isn't so common.

-Wrong. If it works it works and depending on the overall picture there's a good chance it will.
It may very well work. That doesn't mean it will work well.
 

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If the idea is to get back into shape, rather than pick up where you left off and i assume attack the old steep hills with easier gearing why not simply go up hills that are less steep and work towards the goal of climbing the harder inclines later in the season. relatively easy and safe to take off two pounds a week using a combination of diet and exericse. done it many times.
 

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It would really be nice if you would stop pretending you know what you're talking about when you don't but at this point I'm not holding my breath.

-Damage can happen when shifting if the chain/hanger/der combo isn't right to allow it. Pulley wheels turn you know. the speed in which someone turns the chain doesn't matter. But even if you're right that would make your statement even more foolish. Baby in the stand when no harm can be done (according to you) then get on the road and really test it?

-Using a 30 works well for plenty of people. You shouldn't say it won't as a rule because that's just wrong.
 

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It would really be nice if you would stop pretending you know what you're talking about when you don't but at this point I'm not holding my breath.

-Damage can happen when shifting if the chain/hanger/der combo isn't right to allow it. Pulley wheels turn you know. the speed in which someone turns the chain doesn't matter. But even if you're right that would make your statement even more foolish. Baby in the stand when no harm can be done (according to you) then get on the road and really test it?

-Using a 30 works well for plenty of people. You shouldn't say it won't as a rule because that's just wrong.

Really a heavy handed mouthful here even if it made sense. It doesn't. So who looks foolish now?

So you are saying a 30 will work for many people even with a short-cage derailleur? And if the chain length was for anything less than a 28, I really hope you wouldn't just assume it's going to work without changing the chain. If you were, all I can say is best of luck to you, you're going to need it.
 

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It would really be nice if you would stop pretending you know what you're talking about when you don't but at this point I'm not holding my breath.

-Damage can happen when shifting if the chain/hanger/der combo isn't right to allow it. Pulley wheels turn you know. the speed in which someone turns the chain doesn't matter. But even if you're right that would make your statement even more foolish. Baby in the stand when no harm can be done (according to you) then get on the road and really test it?

-Using a 30 works well for plenty of people. You shouldn't say it won't as a rule because that's just wrong.
going from a 28 from a 25 is a 12% benefit, but from 30 over 28 is an additional 7%. You might not find you want to go past 28. I found that on local climbs the 28 works for me. my gravel bike is a compact with a 32 and I don't feel I benefit from it. The only time I felt I wish I had a 32 was on doing some monster climb like I did last summer climbing ventoux when there were times I cursed out my semi-compact and 28 combination(but I made it up!)
 

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Really a heavy handed mouthful here even if it made sense. It doesn't. So who looks foolish now?

So you are saying a 30 will work for many people even with a short-cage derailleur? And if the chain length was for anything less than a 28, I really hope you wouldn't just assume it's going to work without changing the chain. If you were, all I can say is best of luck to you, you're going to need it.
No need for me to address the first comment. your MO of speak now learn the facts latter is pretty well documented already.

Yes, that's exactly what I'm saying. Many people do use that combo with no problems. It depends on the hanger mostly.
 

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going from a 28 from a 25 is a 12% benefit, but from 30 over 28 is an additional 7%. You might not find you want to go past 28. I found that on local climbs the 28 works for me. my gravel bike is a compact with a 32 and I don't feel I benefit from it. The only time I felt I wish I had a 32 was on doing some monster climb like I did last summer climbing ventoux when there were times I cursed out my semi-compact and 28 combination(but I made it up!)
What I meant by works for plenty of people was mechanically speaking. I wasn't trying to make ratio recommendations.
 
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