david58

My wife's bike as a 105 compact double, with an 11/28 cassette. I would like to install a 12/30 for her. Today, the issue is hills more than speed, so losing 11 to go to 12 won't be a big issue.

My question is related to the Tiagra cassette. What is the difference between it and the 105 (aside from the fact that the 105 is the 11/28)? Are there any compatibility issues?

jimc101

As long as you are looking at this year models (4600 & 5700 series) No compatibility issues, Tiagra only went 10 speed this year and there will be big issues using previous versions which are 9 speed, the finish will be better on the 105, but nothing wrong with the Tiagra.

HillRider

As long as the number of cogs match your shifters, all Shimano cassettes are interchangable from Dura Ace through Sora and XTR to Deore and even lower. Most road rear derailleurs won't handle either the largest cog or the "wrap" needed by the MTB cassettes but otherwise use what you like.

dsbrantjr

david58: If you put on a cassette with a larger big cog you will probably need a new, longer chain as well, provided the old one was properly sized to begin with.
Here's what Sheldon Brown has to say about it: https://sheldonbrown.com/derailer-adjustment.html#chain

Puget Pounder

A 12/30 might not work with the road derailleur as HillRider alluded to. I think road derailleurs are conservatively maxed out at 27?

david58

According to the mechanic that I would have do the work, he believes there is no problem with going as far as 30, but no farther without modification of the derailleurs. I have confidence in him, but just curious about the Shimano compatibility - so far he's done more custom stuff to achieve this.

tru

no compatibility issues.

weight, materials, design, finish might be different. look it up.

going beyond 27t on a shimano road rd is hit or miss.
probably works fine, but no guarantee. gotta try.

dave35

Some people have had success using shorter-cage derailleurs with replacement (longer) B-tension screws (any M3 [?] bolt will do). If it's a short-cage 105, this might work if the 30 causes trouble initially. The short cage can cause chain length issues with the big/big and small/small gears, but the jump in chain wrap is small enough that this shouldn't be a problem. If replacing the chain, add an extra link to allow for the bigger cogs in back, and absolutely avoid small/small (chain tension will be too low).

However, the RD is probably a mid/long-cage 105 because the stock cassette has a 28 (OP can correct me if the OEM cassette was smaller), and should take a 30 without problems. It *might* even take a 32.

jimc101

For road Shimano RD, the short cage (SS) will run up to 28T fine (it says this on the retail box), I have a 5700 (SS) with a 11-28 running sweet, a Medium cage (GS ) will run a 32T, I have used a 5700 (GS) with a 11-32 (SRAM PG1050) again, no issues, any more and you will probably run into issues.

For compatibility with other Shimano parts, we are talking 10 speed here, and there is NO compatibility between the MTB (Dyna-sys), Deore, SLX, XT & XTR and Road Tiagra, 105, Ultegra, Dura Ace cassettes, 9 speed there are no compatbility issues

HillRider

I know Dyna-sys MTB 10-speed shifters and derailleurs are not compatible with road 10-speed shifters and derailleurs but does that incompatibility extend to the 10-speed MTB cassettes too? i didn't think it did.

fietsbob

May hear a noise when guide pulley is in contact directly,
with the chain which is on the cog.
rather than having there be air on one side of the chain opposite the guide pulley..

AEO

I think the differences are in manufacturing and tolerances accepted.

105 and tiagra cassettes both look like they are stamped from sheets of metal.
the 105 looks slightly better in terms of polishing and sanding done afterwards.
it's not until you get up to ultegra that you get to see casted parts.

I would just save money and buy the cheaper stuff, but ONLY if it comes in the size required.

dave35

I may have misunderstood this sentence, but I think you are being a bit conservative. The *only* weird groups are the 'Dyna-Sys' ones (which are Shimano's latest attempt to break compatibility and confuse innocent mechanics without improving anything in particular); older (and new non-Dyna-Sys) 9-speed mountain bike RDs compatible with any road shifters. A 9s long-cage Deore RD works fine with 10s road shifters and cassette, and so should any 10s Shimano stuff that's not 'Dyna-Sys'.

I thought Shimano had learned their lesson when they gave up on the Dura Ace cable pull weirdness...

EDIT: Looks like Shimano's 10s stuff IS all Dyna-Sys now. This is silly.

Werkin

The 105 weighs less, it has an aluminum carrier for the large sprockets rather than steel spokes for each cog. They both have the same plating and tooth profiles.

Here's a thread started by Andy_K https://www.bikeforums.net/showthread...speed-cassette.