upgrading 12 sp Shimano 105 to STI?

I have an older steel frame bike with Shimano 105 indexed 12 sp downtube shifters. I am looking at
two possible upgrades and am wondering if these can be done. In both these cases I am thinking of
keeping the deraillers but am uncertain if they will work with the suggested upgrade parts. Thanks
in advance for your help.

Possibility 1) keep the front/rear deraillers but replace with a 7 sp freewheel and find some 7 sp
STI shifters.

Possibility 2) keep the front/rear deraillers, flair rear tiangle from 126mm to 130 mm, get a 9 sp
cassette/wheel, get 9 sp STI shifters.

 

In article <[email protected]>, "gsk" <[email protected]> wrote:

> I have an older steel frame bike with Shimano 105 indexed 12 sp downtube shifters. I am looking at
> two possible upgrades and am wondering if these can be done. In both these cases I am thinking of
> keeping the deraillers but am uncertain if they will work with the suggested upgrade parts. Thanks
> in advance for your help.
>
> Possibility 1) keep the front/rear deraillers but replace with a 7 sp freewheel and find some 7 sp
> STI shifters.
>
> Possibility 2) keep the front/rear deraillers, flair rear tiangle from 126mm to 130 mm, get a 9 sp
> cassette/wheel, get 9 sp STI shifters.

I started with a similar bike (6v 105 indexed on steel frame) and went to a Sora 8v brifteur setup.
The derailleurs will not need to be changed, as long as you respect their capacities. modern fders
might work a little better (less trimming to avoid noise) than the old one. I didn't bother to
properly spread the frame, so now I have to spread the dropouts each time I drop the rear wheel. Not
a big deal. I also had to re-dish the wheel and do a freehub body transplant, and of course replace
the shifter. I was lazy and cheap, so I retained the front DT shifter.

I think DT or barcon shifters are still available for 8 and 9 speed if you like them better.

The parts for option 2 are not too expensive, except for the brifteur. You'll need an 8v or 9v
freehub body ($20?), new chain, new cassette, new shifter (and maybe brake?) cable, and cable stops
for the downtube mounts (?). eBay, local bike shops, and the various active retailers in this
newsgroup are all good sources for parts.

I wouldn't bother with possibility 1. It saves you little unless you get the parts really cheaply,
and the only advantage is not spreading the frame, which is a minor thing.

--
Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

 

"gsk" <[email protected]> wrote in message news:[email protected]...
> I have an older steel frame bike with Shimano 105 indexed 12 sp downtube shifters. I am looking at
> two possible upgrades and am wondering if these can be done. In both these cases I am thinking of
> keeping the deraillers
but
> am uncertain if they will work with the suggested upgrade parts. Thanks in advance for your help.
>
> Possibility 1) keep the front/rear deraillers but replace with a 7 sp freewheel and find some 7 sp
> STI shifters.
>
> Possibility 2) keep the front/rear deraillers, flair rear tiangle from
126mm
> to 130 mm, get a 9 sp cassette/wheel, get 9 sp STI shifters.
>
>

With Shimano's integrated shifter you will need a new front changer. The Campagnolo system is not
only cheaper and more durable, it is compatible with your existing front changer and crank:

http://www.yellowjersey.org/ergokit.html

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

 

>With Shimano's integrated shifter you will need a new front changer. The Campagnolo system is not
>only cheaper and more durable, it is compatible with your existing front changer and crank:

In my experience many of the Shimano front derailleurs that came with 6 and 7 speed SIS will work
with Shimano STI shifters. And of course it is likely that the rear derailleur will also work.

Personally I think bar ends are a good solution in a situation like this one.

jon isaacs

 

Jon Isaacs wrote:
>>With Shimano's integrated shifter you will need a new front changer. The Campagnolo system is not
>>only cheaper and more durable, it is compatible with your existing front changer and crank:
>
>
> In my experience many of the Shimano front derailleurs that came with 6 and 7 speed SIS will work
> with Shimano STI shifters. And of course it is likely that the rear derailleur will also work.

In general, STI front derailer/chainring choice is pretty fussy for _triples_ but not at all
for doubles.

For a double setup, you really only need two positions.

The low gear setting has the cable loose, so it is regulated only by the derailer's low-gear
limit stop.

The high gear setting is the only one that needs to be indexed by the shifter.

Worst-case on a double is that you might have to double-click the shifter

Sheldon "Double, Double, Toil & Trouble" Brown
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