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Old 10-14-10, 07:56 PM   #1
phx1973
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Delayed Gear Shifters

You will have to excuse a newbie question, of something that i'm sure has been discussed in these forums at length...I have a used Motobecane Record (Road Bike) that supposedly has about 100 miles on it. I took it to my LBS and they said a tuneup probably wasn't necessary unless I was having problems. Well guess what, now I seem to have found a problem. I have about a 4.3 mile commute to and from work, and today on the way home I noticed that when I shift gears, it does not engage right away. Sometimes a few seconds go by and then it shifts, sometimes not at all. Then I might try shifting up or down again, and I can hear it shift both gears at once. Doesn't seem good to say the least, but I know so little about bike mechanics, I thought I would check in here.

What say you?
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Old 10-14-10, 08:20 PM   #2
Scrockern8r
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If this is happening in most gears, it sounds like you got some dirt in the system, or perhaps a kink in the housing somewhere. Check that out and lube as necessary. Also, the indexing could be off.
Trim adjustment is most likely...

Validate indexing first. Turn the adjusting barrel "in" (into the dérailleur) just a little bit. I'd recommend about a quarter turn at a time. This should hasten shifting into higher gears (smaller cogs) and run through the gears to see if there is improvement. Lather rinse, repeat. If you go too far, it will have slow down shifting (into bigger cogs). Then you will need to turn the adjuster "out" (as if you are removing it from the dérailleur). Repeat until it shifts both ways equally.
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Old 10-14-10, 08:26 PM   #3
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How old is this bike? Does it even have indexed (click) shifting?

If it is indexed shifting, you may not benefit from a full 'tune up' but probably just need some minor adjustments, or maybe a cable replacement or cleaning.
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Old 10-16-10, 09:54 PM   #4
phx1973
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Quote:
Originally Posted by LarDasse74 View Post
How old is this bike? Does it even have indexed (click) shifting?

If it is indexed shifting, you may not benefit from a full 'tune up' but probably just need some minor adjustments, or maybe a cable replacement or cleaning.
Good question. I am actually not sure, but I think the bike is a 2007, seems to have pretty modern components all the way around. Either way, I appreciate the suggestion about doing some minor adjustments, rather than a full tune-up. I think you may be right. Thanks again.
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Old 10-16-10, 10:39 PM   #5
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If it is occurring primarily on the the down shift to smaller ring or rear gear, check the cables going under the bottom bracket. That is the highest friction point in the system and also the area most likely to pick up crud from the road as well as corrode from exposure to road salt, or puddles. It is in direct line of the front tire as it flings debris/water during front wheel rotation.

If the cables in this area have a white haze, the zinc plating is starting to fail and will roughen the cables a bit as well as swell and get grabby entering the cable housing at the base of the down tube. If you plan to keep the bike for a long time, and ride in all weather, replace the cables and housings with stainless cables, a bit pricier, but you will never replace the cable again for rust until they mechanically fail.
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Old 10-17-10, 01:02 AM   #6
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Very likely all that you need is to slightly adjust the thimble on the derrailleur to even the up and downshifts. This sort of periodic adjustment is extremly basic and should become second nature to you. If you didn't know about this and don't know how to do it then it is high time you learned. There are a few basics about riding a bike that all riders should know and trimming the cable to even up the shifting is one of them.

If you do know about this and tried it and the shifting is still being delayed then you can move on to suspecting a frayed or gunked up cable or a housing that the cable has worn a tight fitting groove into the inner lining and it's grabbing at the cable. If cleaning the cable and housing out doesn't fix it then swap out the housing. If the cable is kinked or frayed at all then swap that out as well. Once you do that and re-trim the shifting it should be good for a while.
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Old 10-17-10, 01:10 AM   #7
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sorry i just a newbie here too
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Old 10-17-10, 07:50 AM   #8
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phx1973, I just had a similar problem on a bike I'd just rebuilt. I had hesitation and some non shifts that'd end up double shifting in the middle of the cassette. This type of failure typically happens with cable housing reseating itself at one end or the other of where it seats.

There is a barrel adjuster on the rear derailleur that positions the cable housing. Screw the barrel slightly outwards (CCW) if failing to shift to a larger gear, the reverse if to a lower gear. You'll need to have the rear wheel off the ground and crankarm clearance as you're going to be up/down shifting until the adjustment is correct. It's a trial and error thing and you'll likely make things worse before better, don't worry about it as you're learning.

Brad
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Old 10-17-10, 08:31 AM   #9
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The reason you see two different causes above (essentially friction and adjustment) is that the fix depends on where you are experiencing the delay. If the delay happens when you are shifting to higher gears (smaller cogs) then the problem is friction, because on those shifts it it the derailleur spring pulling the cable that is completing the shift. If it happens when shifting to higher gears (larger cogs) then it is an adjustment issue. Adjustment cannot make the shift in both directions slow, and only very high friction could cause a slow shift in both directions. If you are somehow experiencing delay in both directions then either you have both of the above problems or something is seriously wrong with your shift lever.
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Old 10-17-10, 09:53 AM   #10
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In the old days the technique was overshifting, push the lever pulling on the derailleur
just past the derailleur pulley wheel being centered over the cog,
then when the gear completely engaged in its new position re center the lever back.
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