I have a Cannondale T700 Touring bike that I bought in 1994. I upgraded the components to Shimano Ultegra 600 with STI shifters. The rear derailleur is Ultegra 7/7 with an HG 90 8 Speed Cassette (13x26). I know this from the receipt that I still have. The front is a triple chain ring, but in 1994, the STI shifters did not do 3. So we found an aft4ermarket piece that you could add at the shifter to make it work 2 rings at a time (top 2 or bottom 2) by flipping the lever which lengthened and shortened the cable. After many years, my bike fell the other day and when I tried to catch it, I missed and grabbed the shifting cable. It broke the shifter where this added part connects and now when you try to flip the lever, it turns/spins at the connection point and wont work. Photo is attached. While I could replace the Ultegra 600 with a used one from EBay, they are pricey and I am considering whether it makes more sense to buy a triple shifter and make it easier to use all three rings. Problem is I am totally inexperienced in componentry don't have any idea what will fit/work, and I don't know what I need to know to figure that out. For example, can I buy a used Shimano Ultegra ST-6703 Triple STI Shifter off eBay and just put it on - or will I need new front derailleur, chain rings, what do I need to know.
Shimano freehubs are identical for 8, 9 and 10 speed cassette. Any Shimano HG compatible hub that will hold a 8 will take a 9 or 10 just as easily. 7 speed is narrower.
The 2303 does allow trimming of the front shift. The 2300/2303 stuff is no longer the current offering, which is why prices are very reasonable.
I have a pair of Microshifts they are... well... I found it to be really difficult to set up the brakes correctly with them, but this was on a Frankenbike (one with Mafac Competition brakes = impossible to get clearance and braking) and on my tourer (tried to get them to work with the travel agent adapters for v-brakes, which should work). The Frankenbike is now scrapped, the tourer is back to flat bar. My feeling is that they pull the wrong amount of cable (= not enough).
I have to be honest: I do not like Shimano's low end stuff. I test rode a bike with Sora components (the lowest named road group) and it was scary: the levers felt very... squishy, inexact, unsafe. Might be better now.
I would try to get 2012 or earlier Tiagra STIs, as they are still 9 speed. On the other hand: You can just replace the left STI with another (newer) one, but I would try to find one that is shaped similar, it might look and feel weird to have two different STIs otherwise.
Oh, and you can also go up all the way to 10 speed (with the 2013 Tiagra), as Nigel noted: the hubs are the same, but chains and cassettes are more expensive and it does not really do a lot (except having either a wider spread on the cassette or narrower steps between the gears). The dérailleurs should be compatible, as far as I know only the 10 speed MTB stuff is different.
I have been a little concerned about the shape of the hoods because that is where I ride 90% of the time. I was hopeful a more modern Shimano like the Ultegra or the Tiara you mention might be very similar to my 18 year old 600's. As to changing it all - by the time I am done I would rather buy a new bike and don't want to do that yet ($$$$$). Thanks for the insights.
And I tried to figure out when the Ultegra group first had a triple front thinking it might be most comparable in shape but haven't been able to figure that out.
I believe Ultegra had a triple crank set until recently, the 105 does still have it. When searching for it, the component id should have a 3 as the last digit, like STI ST-5603, which is the... (2011 I belive) an older anyway 105. The shape of the hoods has changed quite a bit in the last four years, I think.
The cheapest sets at my usual suspects is about 100 € (for the 105s) or 90€ (for Microshift), both for the pair. I guess some shops may still have Tiagras in stock? I just checked the bay, nothing sensible here...
Ultegras are... pricey. Even the NOS (new old stock).
Slowestpoke, do you remember who made that lever that gave you the ability to use a double shifter to shift a triple chainring? If you live in the South San Francisco Bay Area I have a 600 shifter not in use.