Bicycle Mechanics - Can I run a 105 drivechain using 8 speed Sora shifters?

Some advice would be appreciated. Over the months I’ve been slowly converting my Sora equipped touring bike up to105 spec. So far I’ve only upgraded the front and rear mechs.

Next upgrade I want to replace the Sora triple with a 105 part. Since my chain and rear sprockets are now worn I’m also considering upgrading the rear cassette to 9 speed in anticipation of swapping the Sora shifter for 105’s further down the line.

My question is: Can I run a 105 triple with 9 speed chain and 9 speed rear cassette using 8 speed Sora shifters? How will this affect the shifting and is there any other options to help me make this transition?

The shifters have to match the cassette or the indexing will be goofy.

As RG said, the shifters, chain and cassette have to match to work properly. Since cassettes and chains are relatively cheap compaired to the shifters just replace your 8-speed items or go all the way to 9-speed with everything.

BTW, 9-speed 105 brifters are now available at very good prices since they are "obsolete" now that the 10-speed 105 is available. That won't last and fairly soon they will go from "obsolete" to "rare" and the prices will go back up. If you want to do this upgrade, you should really do it soon. 9-speed chains and cassettes will be around for a long time but the brifters will be a good deal for a limited time.

Unfortunately, Retro grouch is right. The spacing between sprockets is different from 8 speed to 9 speed parts. This means that they must be used with the correct shifter, otherwise there will be a mis-match in derailleur position across the cassette, even if one index position is set correctly, that cannot be tuned out by cable adjustments.

Cheers,

Ed

Ok, so what about upgrading the sora triple to 105? will the 105 front chainrings be compatible if i keep the sora shifters and 8 speed cassette?

yeah, assuming they're all triple it'll work, but crank/chainrings would be my lowest priority to upgrade.

Some advice would be appreciated. Over the months I’ve been slowly converting my Sora equipped touring bike up to105 spec. So far I’ve only upgraded the front and rear mechs.

Next upgrade I want to replace the Sora triple with a 105 part. Since my chain and rear sprockets are now worn I’m also considering upgrading the rear cassette to 9 speed in anticipation of swapping the Sora shifter for 105’s further down the line.

My question is: Can I run a 105 triple with 9 speed chain and 9 speed rear cassette using 8 speed Sora shifters? How will this affect the shifting and is there any other options to help me make this transition?

Replacing the Sora crankset with a 105 one won't make any significant improvement, just save a few grams.

Converting to 9-speed is a worthwhile modification if you find the present gearing inadequate. Spend your money on the new 9-speed shifters before changing the crank, that's a better use of your resources.

The 8-speed shifter won't work with a 9- speed cassete, but a 9-speed shifter will work with an 8-speed cassette...however you say your cassette and chain are already worn, so my advice is go go for the 9-speed shifters, 9-speed cassette, 9-speed chain, and leave the crank alone until you win the lottery. Sora cranks are quite nice, actually, and the Sora chainrings are much more long-lasting than the 105 ones.

Sheldon "Picking And Choosing" Brown

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| Aerodynamics don’t make a difference. |
| How much do you hate riding that your ten mile ride |
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The Sora crank arms are really quite nice. The major difference between the 105 and Sora is the chain rings. The Sora's are steel. They are a bit heavier than AL, but they will last and last. That seems like a good thing, especially on a touring bike.

Get the shifters, cassettes and chain. 105 9 speed stuff is a steal.

Sora cranks are quite nice, actually, and the Sora chainrings are much more long-lasting than the 105 ones.
Huh? Why?

Huh? Why?

Because they are steel rather than the pressed AL in the 105s.

Because they are steel rather than the pressed AL in the 105s.
Ok, that explains it. In that case, I expect the weight difference to be more than "a few grams".

Ok, that explains it. In that case, I expect the weight difference to be more than "a few grams".

They aren't exactly feather weight, but if you are more concerned with durability they are a good choice.

They aren't exactly feather weight, Neither would 105 be. Hence, sheldon's advice.