Shimano 105, 2005, 27gears, ST-5510 shifter and derailler RD-5501. used ~3 month.
Hi. I've noticed while biking when I am upshifting one click (example from cog 7 to 6, or 8 to 7, 6 to 5), it seems to miss so I have to do it again but with more power. Is that possible to make this more firmer, so I use less energy to upshifts? It seems to needs a lot of hand movements to upshifts, whose I does not have BIG hands, so this is annoying especially when upshifting in the lower regions. I have lower (zero!) error rate in the higher regions (1,2,3,4)
(*little* bit more firmer and responsive)

...............<.<....
1 2 3 4 5 6 7 8 9

Any comments/help to fix this?

Shimano 105, 2005, 27gears, ST-5510 shifter and derailler RD-5501. used ~3 month.
Hi. I've noticed while biking when I am upshifting one click (example from cog 7 to 6, or 8 to 7, 6 to 5), it seems to miss so I have to do it again but with more power. Is that possible to make this more firmer, so I use less energy to upshifts? It seems to needs a lot of hand movements to upshifts, whose I does not have BIG hands, so this is annoying especially when upshifting in the lower regions. I have lower (zero!) error rate in the higher regions (1,2,3,4)
(*little* bit more firmer and responsive)

...............<.<....
1 2 3 4 5 6 7 8 9

Any comments/help to fix this?
I'm not sure which direction you are trying to go here. If you are having trouble 'upshifting' (going to a smaller cog), try turning the barrel adjuster on the RD 1/4 turn clockwise. If the trouble is 'downshifting' (going to a larger cog), turn it counter clockwise. - TF

I'm not sure which direction you are trying to go here. If you are having trouble 'upshifting' (going to a smaller cog), try turning the barrel adjuster on the RD 1/4 turn clockwise. If the trouble is 'downshifting' (going to a larger cog), turn it counter clockwise. - TF

oops. With "upshifting" I am meaning to bigger cogs at the cassette... (not at the crankdrive)
I have tried that, and it helped a little, but the problem is still there, althought I does not know how it affects the precision of the upper range. (testing it at the ground with the backwheel removed...)
What I was meaning was that the angle the shifter needs to have when upshifting to bigger cog -> can it be reduced?
When it is at the smallest cog (gear 9, with 12teeth) it needs higher angle to upshift than the middle of the cassette

(2-8). Then to get at the 1(biggest cog), it need a greater angle in shifting arm to upshift than cog number 2 to 8) ... A little weird...

I've measured the needed angle to shift:
9 to 8 :~30 degree (smallest cog, 12 teeth up to the next smallest cog 13teeth)
8 to 7: ~25 degree
7 to 6: ~25 degree
6 to 5: ~25 degree
5 to 4: ~25 degree
4 to 3: ~25 degree
3 to 2: ~25 degree
2 to 1: ~30 degree (up to the biggest cog)

Any possibility to reduce the needed usage of the degree for changing gears?
I hope that I clear enought.

I think you are making this too complicated on yourself. Follow TurboTurtles advice.

oops. With "upshifting" I am meaning to bigger cogs at the cassette... (not at the crankdrive)
I have tried that, and it helped a little, but the problem is still there, althought I does not know how it affects the precision of the upper range. (testing it at the ground with the backwheel removed...)
What I was meaning was that the angle the shifter needs to have when upshifting to bigger cog -> can it be reduced?
When it is at the smallest cog (gear 9, with 12teeth) it needs higher angle to upshift than the middle of the cassette

(2-8). Then to get at the 1(biggest cog), it need a greater angle in shifting arm to upshift than cog number 2 to 8) ... A little weird...

I've measured the needed angle to shift:
9 to 8 :~30 degree (smallest cog, 12 teeth up to the next smallest cog 13teeth)
8 to 7: ~25 degree
7 to 6: ~25 degree
6 to 5: ~25 degree
5 to 4: ~25 degree
4 to 3: ~25 degree
3 to 2: ~25 degree
2 to 1: ~30 degree (up to the biggest cog)

Any possibility to reduce the needed usage of the degree for changing gears?
I hope that I clear enought.

Short answer is: this is how the stuff works. I just rebuilt my commuter with 105 9sp. when you shift the rear d. to a larger cog, sometimes you don't throw the shift lever enough and you don't get quite enough cable tension change to shift the gear. I have the exact problem. Mine is DIALED, but this problem you are describing still exists. Its similar to having a manual transmission in a car and not moving the stick far enough to get into gear.

Solution: If you want superbly accurate shifting, either figure out how to put a SRAM X0 gripshift onto your rig, or try a midrange Campy drivetrain like Centaur or Veloce. Hate to say it, but you get what you pay for.

Short answer is: this is how the stuff works. I just rebuilt my commuter with 105 9sp. when you shift the rear d. to a larger cog, sometimes you don't throw the shift lever enough and you don't get quite enough cable tension change to shift the gear. I have the exact problem. Mine is DIALED, but this problem you are describing still exists. Its similar to having a manual transmission in a car and not moving the stick far enough to get into gear.

Solution: If you want superbly accurate shifting, either figure out how to put a SRAM X0 gripshift onto your rig, or try a midrange Campy drivetrain like Centaur or Veloce. Hate to say it, but you get what you pay for.
NOT - Try again. When adjusted correctly a 105 will shift like a manual/auto transmision. If it clicks, it shifts. - TF

Incorrect cable tension is the most common cause for poor shifting as was already pointed out.

You also need to make sure the rear derailleur is positioned properly (centered) on the largest cog & on the smallest cog first. That's what those little screws are for on the back of the RD housing. Index shifting is based on a fixed throw or movement between the other intermediate cogs and is dependent on having the correct cable tension to move everything (up or down) the proper distance.

This also assumes that the RD is in alignment (parallel) with the cassette & that the RD hasn't taken a hit. If the hanger or the RD are even slightly bent, all bets are off for perfect shifting.

But what do I know. I'm just a backyard wrencher that started fiddling with index shifting back in '86...

Go to the Shimano web site, click through to the correct grouppo, then download the service/adjustment manual. Even low end Shimano stuff will work one click, one shift if it's adjusted correctly.

also check to make sure that the derailleur hanger is not bent. there's a fancy tool to check this, but if you just eyeball the bike from behind (and it is easier to see when chain is on a bigger cog), the derailleur jockey wheels should be parallel to the cogs (perfectly vertical) for good shifting. if it's not, the hanger could be bent (and can be straightened a little with an adjustable wrench) or the derailleur may have just developed some slop--which does tend to happen faster with cheaper derailleurs, but 105 is pretty good, and any derailleur that gets dropped on its side a couple of times will too, no matter how expensive.

Shimano 105, 2005, 27gears, ST-5510 shifter and derailler RD-5501. used ~3 month.
Hi. I've noticed while biking when I am upshifting one click (example from cog 7 to 6, or 8 to 7, 6 to 5), it seems to miss so I have to do it again but with more power. Is that possible to make this more firmer, so I use less energy to upshifts? It seems to needs a lot of hand movements to upshifts, whose I does not have BIG hands, so this is annoying especially when upshifting in the lower regions. I have lower (zero!) error rate in the higher regions (1,2,3,4)
(*little* bit more firmer and responsive)

...............<.<....
1 2 3 4 5 6 7 8 9

Any comments/help to fix this?
For what it is worth I just *upgraded* from a 2005 era Ultegra shifter/derailer (9 speed) set to a 2007 105 set (10 speed). The 105 is superior in my humble opinion. The shifting is more crisp and I have access to more gears on the 105 (it seems I can access a higher percentage of the available gears). I am very impressed.

I'm using a full 105 drivetrain (cranks, chain, deraillers, shifters, cassette) and I recommend this combo. On the Ultegra-equipped bike I had a Truvativ crank which was nice, but I definitely notice an improvement in the 105 crank.

I hearing more and more opinions about the gaps between 105/Ultegra/Durace being more of a durability/weight/cost tradeoff as opposed to performance.