Internal geared BB and enclosed chain transmission mountain bike.

On Fri, 10 Jun 2016 08:51:09 -0700, Jeff Liebermann
wrote:

On Fri, 10 Jun 2016 11:33:08 +0700, John B.
wrote:

http://802.11junk.com/jeffl/pics/bicycles/slides/Miyata-610.html

Not to worry. I started with http://802.11junk.com/jeffl/ ands just
followed the crumbs of bread :-)

The photo of the Miyata seems to show the shifters mounted on the L.H.
side of the down tube?

Nope. The Suntour "Symmetric" shifters are centered on the downtube.
https://www.google.com/search?q=suntour+symmetric&tbm=isch
https://www.youtube.com/watch?v=FyR9Sezf1PM
http://www.ebay.com/itm/New-Old-Stock-Suntour-Top-Mount-Shifters-Friction-Braze-On-Model-/271813768566
http://www.velobase.com/ViewComponent.aspx?ID=4cb7e658-e09e-4950-a283-2787beac2bb0
http://www.bikeforums.net/classic-vintage/514867-test-your-wits-suntour-symmetric-reassembly-challenge-pics.html
http://www.bikeforums.net/classic-vintage/514867-test-your-wits-suntour-symmetric-reassembly-challenge-pics.html#post8484924
The shorter and more direct cable run between the shifters and
derailleurs produces a less sloppy shift. No detents as it was
designed before indexed shifters became fashionable. The location of
the shifters on the downtube are fine for a "touring" bike, where one
does little shifting. I like them because the location moves the
shifters and some of the cable clutter away from the handlebars. The
handlebar space is better suited for lighting, smartphone, camera, and
horn type clutter.

They're also available in a clamp on configuration:
http://www.ebay.com/itm/New-Old-Stock-Suntour-Clamp-On-Model-Shifters-5-6-7-Speed-Friction-Compatible/271775719667

Yes, I have down tube shifters on two bikes in Bangkok, but mine are
the braze on lug versions mounted on either side of the down tube.
--
cheers,

John B.