Bicycle Mechanics - friction shifting question

I put Shimano 105 vintage on my Pinarello build.I have, the option of index or friction and though its probably my fault,index skips my next to smallest cog and goes right to the smallest.Friction is really good and I got used to it on my other bike.I'm wondering though the shifting ark is very short.It's down tube and from 1-6 speeds is probably just 45 degrees.My Trek is much longer say 100 degrees.(where 180 degrees the shifter is straight down.)Is this normal?Is it possible to increase the arc?Recommended?I hope I"m making myself clear.Thanks!!

That's more a function of derailleur movement than the shift lever. If your derailleur requires a lot of cable pull to shift it will make the shifter go further. I use friction with 10 speed and the shifts require just a touch.

You could hypothetically file down the groove in which the cable sits in the shifter, making the effective "axle" smaller, thus requiring a longer arc to pull the same amount of cable. Wouldn't recommend it, though...

When I would ride my old suntour friction Raleigh then ride my indexed shimano Trek (both 6s) I would really notice the much shorter throw of the shimano shifters.

You could hypothetically file down the groove in which the cable sits in the shifter, making the effective "axle" smaller, thus requiring a longer arc to pull the same amount of cable. Wouldn't recommend it, though...

If done carefully, it should have the desired effect... only leaving the indexed mode useless, of course.

Care must be taken to ensure the extra travel dictated by the smaller radius is accommodated by the shifter's mechanism (micro-index, balance spring, travel stop)... slight modification might yield some more travel.

You may also be able to route the cable the other side of the pinch bolt on the derailleur. Depending on the derailleur, that can alter the amount it moves for a given amount of cable pull by a considerable amount. When I did it by accident with an indexed 7-speed Shimano derailleur, it moved all the way across the cassette in 4 clicks of the lever.

Seems it's working as it should,By the way which side of the pinch bolt is it supposed to be on?

I don't know, I'm not familiar with the exact model of derailleur, but if you post a few pictures, I might be able to tell you. Depending on the design of the thing, routing the cable the "wrong" side of the pinch bolt may increase the distance the cage moves for a given amount of lever travel, or decrease it, and the amount will also vary. Obviously, decreasing it is what you want, but again, I can't say whether it'll have that effect without seeing the derailleur.

Either way, the indexing won't work if you do that, but friction will still be fine.

Whenever I encounter a rear shifting issue that doesn't respond to normal tuneing efforts the first thing that I do is to check the derailleur hanger alignment. Most of the time that fixes it.

It isn't a big deal to do, but you pretty much need a gauge to do it. If the derailleur hanger alignment isn't right, nothing else is going to fix it. If the derailleur hanger alignment is right, you can rule that out as being the source of your problem.

I put Shimano 105 vintage on my Pinarello build.I have, the option of index or friction and though its probably my fault,index skips my next to smallest cog and goes right to the smallest.
Does the shifter indexing match the number of freewheel/cassette cogs? For example do you have a 6-speed indexing shifter operating on a 7-speed freewheel or cassette?

Does the shifter indexing match the number of freewheel/cassette cogs? For example do you have a 6-speed indexing shifter operating on a 7-speed freewheel or cassette?
I'm not sure the index shifters range.Early shimano 105-1050 series.freewheel is 6 cogs.By the way the derailleurs jockey wheel fell off today!Could be it wasn't on right for a while.Anyhow I've put the wheels back on my trek 760 till I build the new ones so the Pinarello is going to sit for awhile.

Seems it's working as it should,By the way which side of the pinch bolt is it supposed to be on?

If you can increase the distance from where the cable is clamped to the upper parallelogram pivot, this will increase the amount of cable travel required to move the derailleur a given distance.