Bicycle Mechanics - STI barrel adjuster cable stop w/ lever

Do I get the award for the title with the most descriptors?

I'm setting up some barend shifters on a frame with downtube bosses, so I need some stops, and adjustable barrels would be ideal. In searching for these, I've come across some that are equipped with a lever on one stop. I've never used STI road shifters. What is the function of the lever?

It makes adjustments while riding easier.

Al

It makes adjustments while riding easier.

Al

Ah, thank you. Is reliability diminished at all vs. traditional barrel adjusters? I'm thinking the lever may eventually slip?

The cable stop with the lever has four coarse click-stop adjustments rather than a smooth screw-in/out range. I have these on two frames, and in the real world it doesn't make any difference.
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Ah, thank you. Is reliability diminished at all vs. traditional barrel adjusters? I'm thinking the lever may eventually slip?

The lever never slips as it is ratcheted. This type of cable stop came with higher line Shimano STI brifters, Ultegra and Dura Ace. The lower groups had a regular barrel-type adjuster on both sides. Both types work equally well.

Actually rear derailleur adjustments are almost always made with the barrel adjuster mounted on the derailleur itself so the down tube stop adjustment is more decorative than useful.

A down tube adjuster is essential for front derailleur indexing as there is no other adjustment location. For your barcons (friction front shifting) there is really no need to adjust the front cable tension on the fly so all you need is something to hold the cable housing.

The lever never slips as it is ratcheted. This type of cable stop came with higher line Shimano STI brifters, Ultegra and Dura Ace. The lower groups had a regular barrel-type adjuster on both sides. Both types work equally well.

Also has been included with 105 sets for several years.


Actually rear derailleur adjustments are almost always made with the barrel adjuster mounted on the derailleur itself so the down tube stop adjustment is more decorative than useful.

Try adjusting the barrel adjuster on the RD itself while you are riding (really, don't do that). RD's are more likely to need a little fine tuning during a ride, or race, than an FD, so having a downtube mounted adjuster is pretty important. I think I'd say it's very useful. That's exactly why Shimano made one that's very easy to operate and effect a change in cable tension. I know a Campy-only snob who admitted to me that the only piece of Shimano gear on any of his bikes is that RD lever cable adjuster. He loves it and so do a lot of people.

A down tube adjuster is essential for front derailleur indexing as there is no other adjustment location. For your barcons (friction front shifting) there is really no need to adjust the front cable tension on the fly so all you need is something to hold the cable housing.[/QUOTE]

But, if he chooses to use indexing for the RD then that little downtube lever adjuster will be very nice to have if he wants to tune his RD cable tension without stopping his ride and getting off the bike.

Thanks for the responses. Actually, I'm planning on running some Suntour friction barcons, front and rear, so I suppose the adjusters are not necessary. However, they will be on a frame with downtube bosses...so I need something to stop the housing. I've found some very inexpensive lever versions on ebay, which is why I asked the question. If I ever go index on the rear, I'll have the advantage of the lever adjustment.

Another possiblity for cable stops (if you have a 1 1/4" or 1 3/8" diameter downtube) are the Tektro clamp on cable stops shown on this page:

http://www.biketoolsetc.com/index.cgi?id=70565973610&nr=11&b=&c=&sc=&tc=&q=cable%20stop&s=

I have used these a number of times and they can be very handy. I found them indispensible for converting an early 80's Japanese frame FD to a modern FD.