HMJ

I'm rehabbing a bike for the indoor trainer which came with the Sora ST-3300/3303 brifter set. No matter what I do I get chain rub only in the small chainring/smallest two cogs. It appears there is no trim shift on the ST-3303 but I can hardly find any info on this brifter - even on Shimano's site.

I have found some info on the ST-3304 (Shimano's site included) which - as I understand it - has a trim shift only in the small chainring. So it makes some sense to me that the ST-3303 would not have a trim shift while the ST-3304 does, making it the "next gen" product when Shimano realized the error of their ways

Here's the set up FWIW:

• Bike: 2002 Specialized Allez A1
  
• Left brifter: Sora ST-3303
  
• FD: Sora FD3304
  
• Cassette: Sunrace CSR86 8 speed (new)
  
• Crank: Sugino RD3000 triple 52/42/30
  
• Chain: KMC X8 (new)
  
• Shifter cables: new
  

Other details:

• Outer FD cage is parallel to the large chainring and ~ 2mm above it.
  
• Inner side of chain is barely not rubbing against the inner FD cage when in the small chainring/large cog combo.
  
• No chain rub in any other combo.
  
• I realize cross-chaining is not recommended anyhow.
  
• Bike shifts fine otherwise.

If I ever end up selling it I'll just switch the brifter out to any number of other options. For the purposes of using it on a trainer I expect it will be fine...but I just want to stop wondering if I missed anything


Many thanks in advance!

Iride01 

This seems to indicate is has trim clicks. https://si.shimano.com/en/pdfs/si/6C...000-00-ENG.pdf

With my 105 5800, when I didn't get the trim clicks, it was because my FD wasn't set up properly. Perhaps your limits are not set correctly.

https://si.shimano.com/en/pdfs/si/5E...0D-000-ENG.pdf

It's been too long since I've had to deal with such for me to remember what it took to get the trim to work. There'll be someone along soon that deals with that on a regular basis.

Or did I read that SI wrong and the trim is only on the 2x version of the lever?

icemilkcoffee 

That document actually says that there is trim click in the ST3300, but not the ST3303. I happen to have a pair of ST3300 sitting right on my desk, and I just confirmed that it does have trim clicks both in the up and down direction (not just in the down direction as implied by the manual)

I have no idea why the ST3303 has no trim click. Although I have a good guess - the ST3300/ST3303 started out as 7 speed. The 7 speed cassette is narrow enough that no trimming is needed really. This is why the other 3x7 speed brifter, the RSX ST-A410 has no trim function neither. I am guessing when they changed the ST3300 to 8 speed, which confusingly has the same ST3300 part number, they probably confused themselves and forgot to add trim to the ST3303 left shifter; and thereby necessitating the later ST3304 revision with trim added.

70sSanO

I'm not familiar enough with the differences between ST-3303 vs ST3304. I'm guessing the 3303 (triple 8 speed) doesn't have trim and the 3304 (triple 8 speed) does as icemilkcoffee has posted.

I do know that the ST-2303 triple does not have any trim function as I have a set on one bike.

John

Jicafold

You could use one of these inline cable adjusters.

bboy314

It is normal to have chain rub in that combination (small chainring, smallest couple of cogs). It’s called cross chaining and should be easily avoidable since those gear combos are redundant. Even if the front derailleur doesn’t rub, the chain is likely to rub on the middle chainring when using that combo.

Edit: just realized your OP states that you’re familiar with cross chaining, so there you have it.

AeroGut

I have 3303 shifter and can confirm the lack of trim. On my bike, there's no rub even in the small-small crosschain, but that may be due to longer chainstays or slightly different chainline or the fact that I'm using the 3303 front derailleur with it. The 3304 FD inner plate shape is different from the 3303, which might require setting it a tiny bit farther inboard? You could experiment with a 3303 FD or a BB with slightly longer spindle if it really bothers you, but I would just avoid those gears.

HMJ

I appreciate everyone's feedback. I am now more confident there is no trim shift on the ST-3303 and that I am not missing anything. Now I can rest easy

The bike's maiden voyage on the trainer was yesterday...I did not come very close to using the chain-rubbing combos. Eventually I'll swap the brifter out to one with a trim shift but for now it will do.