Matching cassette (Ultegra) to rear derailleur (105)

[razmaspaz]

This is my first time posting. Hope I'm in the right place. I have a 105 derailleur and a Tiagra? rear cassette. I want to upgrade the bike to an 11-28 and the only two options I can find that are reasonable are the Sram force cassette and a Shimano Ultegra cassette. I'm trying to figure out what I need to swap out to make this work. If I go Ultegra Can I swap the cassette (and possibly chain for wear) or do I need to swap the derailleur, and potentially the shift levers along with it? If I go sram supposedly its compatible, but will it shift poorly because its not shimano?

Thanks ahead of time.

 

[razmaspaz]

Well, of course I could be wrong, but I believe the SRAM Force cassette has 10 cogs ...

The Ultegra cassette may have 10 or 9 cogs ...

Your Tiagra cassette probably has 9 cogs ...

So, the problem you may encounter isn't with the 105 rear derailleur, per se, it will be with your shifters ... and/or chain.

What shifters does your bike have? What is the model number?

I don't know the model number, can't find it on the shifter, but its Tiagra and it is 9 speed, or at least its set up for 9 speed. So is it possible to get a 9 speed cassette that covers 11-28? All this time I thought it was 10 speed.

Is moving to 10 speed a new chain, crank, and shifters?

 

[alfeng]

I have a 105 derailleur and a Tiagra? rear cassette. I want to upgrade the bike to an 11-28 and the only two options I can find that are reasonable are the Sram force cassette and a Shimano Ultegra cassette. I'm trying to figure out what I need to swap out to make this work. If I go Ultegra Can I swap the cassette (and possibly chain for wear) or do I need to swap the derailleur, and potentially the shift levers along with it? If I go sram supposedly its compatible, but will it shift poorly because its not shimano?

Well, of course I could be wrong ...

I believe the SRAM Force cassette has 10 cogs ...

The Ultegra cassette may have 10 or 9 cogs ...

Your Tiagra cassette probably has 9 cogs ...

So, the problem you may encounter isn't with the 105 rear derailleur, per se, it will be with your shifters ... and/or chain ... and, the number of cogs on the cassette!

What shifters does your bike have?

What is the model number?7

 

[alfeng]

I don't know the model number, can't find it on the shifter, but its Tiagra and it is 9 speed, or at least its set up for 9 speed. So is it possible to get a 9 speed cassette that covers 11-28? All this time I thought it was 10 speed.

Is moving to 10 speed a new chain, crank, and shifters?

There will probably be limited advantage to going to a 10-speed cassette/chain + shifter.

If you want a cassette with a wider range, then the most expedient option is to get a 9-speed 11-32 LX cassette and restack the cogs you want with the cogs on your Tiagra cassette -- basically, you would remove the 32t cog & insert an intermediate cog + spacer in the LX cassette.

Your cost will be the cost of the LX cassette (probably, less than $30) + your time vs. $100-to-$300 to change to a 10-speed drivetrain components and/or shifters.

 

[alfeng]

I don't know the model number, can't find it on the shifter, but its Tiagra and it is 9 speed, or at least its set up for 9 speed. So is it possible to get a 9 speed cassette that covers 11-28? All this time I thought it was 10 speed.

Is moving to 10 speed a new chain, crank, and shifters?

FYI. The model number is on the handle body ... beneath the hood, near the clamp.

 

[razmaspaz]

Interesting. So I'm riding a hilly century this summer, hence the need for the 28. I already have a compact (50/34) crank.
Why wouldn't I choose something like

Shimano Shimano HG80 11-28 9-speed Cassette - harriscyclery.net

I can't tell if thats road or not, does it even matter? Sorry for all the questions, but this will be the first time I do more with my bike than just ride it. Its all new to me.

 

[alfeng]

If I go sram supposedly its compatible, but will it shift poorly because its not shimano?

BTW/FWIW. I think Shimano makes the best shifting cassettes.

 

[razmaspaz]

FYI. The model number is on the handle body ... beneath the hood, near the clamp.

ST-4500

 

[alfeng]

Interesting. So I'm riding a hilly century this summer, hence the need for the 28. I already have a compact (50/34) crank.
Why wouldn't I choose something like

Shimano Shimano HG80 11-28 9-speed Cassette - harriscyclery.net

I can't tell if thats road or not, does it even matter? Sorry for all the questions, but this will be the first time I do more with my bike than just ride it. Its all new to me.

Well, yes, you could buy the Harris Cyclery cassette, but why pay $85 + shipping for something you could cobble together for the cost of an LX cassette?

The required skill level is very low ...

I don't remember if the LX cassette is bolted (it uses either a 1mm or 1.5mm Allen wrench) together or riveted (grind off the head) ... either way, it's easy enough to do.
​

Just take the 13t cog from your Tiagra cassette & insert it into the LX cassette's stack ... and (as previously mentioned), remove the 32t cog from the LX stack ... and, you will have the equivalent of the Harris Cyclery 11-28 cassette for a fraction of the cost.