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26-10.-2006, 04:06 AM
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#1 |
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Registered User
Join Date: Aug 2005
Posts: 18
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Precision shifting
I have 2 bikes: A Specialized Hardrock, and a Giant Boulder SE. The HR shifts very smoothly. When I shift from 1 gear to another, it responds precisely, very quick and with hardly a sound. However, my Giant is different. From the day I bought it new, when I shift it, it sometimes takes a couple pedal strokes before it responds, and it grinds sometimes going from one gear to the next. I've attempted to adjust the deraileur using the limiting screws, but that just made it throw the chain if I turned the screws too far in one direction, or it wouldn't shift at all if I went too far the other way.
I should add that both bikes use the same deraileur component group, which is Acera. I would expect that they would work the same, being the same quality. I doubt the bike brands being different would affect anything. Right? So is there any other kinds of adjustment I could make to make it shift more precisely? |
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26-10.-2006, 04:26 AM
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#2 |
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Registered User
Join Date: May 2006
Location: Ohio
Posts: 187
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Re: Precision shifting
First off, the limiting screws are just what they are called...they limit the chain from going off the large ring and small ring by limiting how far the derailleur moves. What happened is most likely cable stretch and you need to readjust the cables and tension.
http://www.parktool.com/repair/readhowto.asp?id=64 http://www.parktool.com/repair/readhowto.asp?id=75 These links will take you to the Park Tool website that describes how to adjust each derailleur and shifter.
__________________
'06 Cannondale R700 |
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26-10.-2006, 04:35 AM
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#3 | |
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Registered User
Join Date: Aug 2005
Posts: 18
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Re: Precision shifting
Quote:
Thank you for the quick reply! I'm surprised my cable is already stretched even though the bike was new, but I'll try to follow the instructions to tighten it. I don't have much (if any) bike mech. experience, so wish me luck! |
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26-10.-2006, 04:42 AM
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#4 | |
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Registered User
Join Date: Jul 2005
Posts: 1,913
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Re: Precision shifting
Quote:
For the time being, try to get some 3-in-1/household into the housing ... |
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27-10.-2006, 06:35 AM
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#5 | |
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Registered User
Join Date: Aug 2005
Posts: 18
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Re: Precision shifting
Quote:
That would be much easier for me to do. I will try that first! |
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12-09.-2007, 07:31 AM
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#6 |
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Registered User
Join Date: Aug 2007
Posts: 23
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Re: Precision shifting
I have been spending two hours trying to adjust my rear gears and ended up frustrated.
I have problems with upshifts but no problems with downshifts. The problem is from the 8th to the 9th gear. Thing is, once it sort of work, I will have problems shifting, particularly 4th to 5th. Once 4th to 5th sort of work, problem will start at 8th to 9th again. A few times I thought I got it, but after test run of 4-5 times shifting the gears, the problems occurs again. I use the small chain ring for 1st to 5th gear, big ring for 6th to 10th generally. I've been adjusting the limit screws and cable tensions. I figured the cable tensions plays the more important role in this context compared to the limit screws, but I'm not sure how to explain! I'm running on 105 shifters, 10-speed cassette 13-25T, and chain. Chainring is FSA Gossamer Mega EXO Compact 36-50T. Mileage aproximately 1,200 kilometres, so I don't think it's because the parts are worn? Is there possibility of a manufacturing fault of the right shifter? Is this normal to not have 100% shifting, or this is just how 105 parts work? --- Generally, the downshifts are very smooth, but upshifts are average. Upshifts sometimes smooth, sometimes goes 'CLUNK', sometimes hesistates, sometimes doesn't shift at all as it stucks hesitating and I have to skip one gear to the next. The major(literally) problem occurs mostly at the middle gears from 4th-6th, and the high gear of 8th -10th gears. Less problems on the other gears, but sometimes still hesitates, particularly upshifts. --- Help me, anyone?  |
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12-09.-2007, 07:57 AM
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#7 |
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Registered User
Join Date: Aug 2007
Posts: 23
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Re: Precision shifting
I have been spending two hours trying to adjust my rear gears and ended up frustrated.
I have problems with upshifts but no problems with downshifts. The problem is from the 8th to the 9th gear. Thing is, once it sort of work, I will have problems shifting, particularly 4th to 5th. Once 4th to 5th sort of work, problem will start at 8th to 9th again. A few times I thought I got it, but after test run of 4-5 times shifting the gears, the problems occurs again. I use the small chain ring for 1st to 5th gear, big ring for 6th to 10th generally. I've been adjusting the limit screws and cable tensions. I figured the cable tensions plays the more important role in this context compared to the limit screws, but I'm not sure how to explain! I'm running on 105 shifters, 10-speed cassette 13-25T, and chain. Chainring is FSA Gossamer Mega EXO Compact 36-50T. Mileage aproximately 1,200 kilometres, so I don't think it's because the parts are worn? Is there possibility of a manufacturing fault of the right shifter? Is this normal to not have 100% shifting, or this is just how 105 parts work? --- Generally, the downshifts are very smooth, but upshifts are average. Upshifts sometimes smooth, sometimes goes 'CLUNK', sometimes hesistates, sometimes doesn't shift at all as it stucks hesitating and I have to skip one gear to the next. The major(literally) problem occurs mostly at the middle gears from 4th-6th, and the high gear of 8th -10th gears. Less problems on the other gears, but sometimes still hesitates, particularly upshifts. --- Help me, anyone? |
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12-09.-2007, 03:06 PM
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#8 |
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Registered User
Join Date: Aug 2003
Location: Sydney Australia
Posts: 465
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Re: Precision shifting
Sounds to me like you've got some cable stretch and the rear mech needs adjusting. If this makes sense then try it out. If not then you really should go back to the shop to get it adjusted.
The main components to pay attention to are the cable, spring and two limit screws. The spring will always try to pull the derailleur to a smaller sprocket (higher gear)...in most cases anyway. To get to a larger sprocket (smaller gear) the cable has to pull against the spring tension and to get to a larger gear the cable has to be released. The two limit screws stop the derailleur from moving past the highest gear/smallest sprocket (high or H screw) or from moving past the largest sprocket and into the spokes (low or L screw). In readjusting a rear mech the first thing you must do is adjust the limits of motion. When I do this I undo the cable completely and pedal to let the derailleur shift under spring tension to the smallest sprocket. Next I adjust the H screw so that the derailleur jockey wheel is directly under the smallest sprocket. You should not have to touch this screw again after that. Then I grab the derailleur and push it by hand (whilst cranking) as far as the limit will allow and adjust the L screw (whilst still holding the derailleur in) until the jockey wheel sits directly under the largest sprocket. Then I let the derailleur go and crank again to get to the smallest sprocket again. That's the limit screws done and they won't need to be touched again. Next I take hold of the cable end in one hand and then use the shifter to pay out all the available cable pulling it through. Then I place it back into the same position it was in before it was undone. Applying tension to it, I then do up the cable clamp. Now its time for the acid test! Start cranking and shifting. If the derailleur is too slow to shift to a smaller sprocket I release some of the cable tension (screw the barrel adjuster in). If too slow to shift to a bigger sprocket then add tension (screw the barrel adjuster out). Derailleurs are often quite sensitive to this adjustment if everything else is in working order. And that's it. Please note that you MUST adjust the limit screws first. There is NO USE WHATSOEVER in adjusting the limit screws while the cable is still clamped in place. It may pay to look at the cables whilst undone to check if there is any unnecessary friction. Also check that the cable is clamped onto the right place on the derailleur. This can have a significant effect. |
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