gear trouble

That sounds like the issues I have when I use my 9-speed rear cassette on my 8-speed trainer bike. Is this a second-hand bike, or something that's been pieced together, by chance?

Definitely not a H/L limit issue. That wouldn't affect shifts through the middle of the cassette or cause gear jumps at all.

ray-ez said:

Hi,

I've been having trouble with gear changes recently, they've not been very smooth. To try & fix the problem, I first adjusted the H & L screws on the rear mech. I then adjusted the cable adjuster to improve the indexing.

It is now improved, but i still sometimes get 'jumps' even when i've been cycling along in one gear for a minute or more! I'll be trundling along, and after a minute or so, it'll decide to jump sprockets. Annoying!

Also, when in top gear, changing the rear gear shift down one click, doesn't result in a gear change, I have to change down 2 clicks to get a change of 1 gear. When moving UP through gears, I have to select a gear, then click the rear gear shift down one click, in order to stabilize the transmission & try to prevent the chain jumping as described above.

Do i need a new chain & cassette? Or do i need to do more fiddling with the H & L limit screws - or the indexing?

Thanks if you can lend a thought!
Ray

have you tried replacing the shift cable and cover ? usually if you have trouble dialling it in , up shifts ok but not down or vice versa then the cause can be a sticky cable - and it´s a fairly cheap thing to do .

frenchyge said:

That sounds like the issues I have when I use my 9-speed rear cassette on my 8-speed trainer bike. Is this a second-hand bike, or something that's been pieced together, by chance?

Definitely not a H/L limit issue. That wouldn't affect shifts through the middle of the cassette or cause gear jumps at all.

I'm 99% sure all the components are original, also it's a problem that's developed over time so I don't think it would be a 'wrong cassette type' issue. But thanks...

ray-ez said:

Hi,

I've been having trouble with gear changes recently, they've not been very smooth. To try & fix the problem, I first adjusted the H & L screws on the rear mech. I then adjusted the cable adjuster to improve the indexing.

It is now improved, but i still sometimes get 'jumps' even when i've been cycling along in one gear for a minute or more! I'll be trundling along, and after a minute or so, it'll decide to jump sprockets. Annoying!

Also, when in top gear, changing the rear gear shift down one click, doesn't result in a gear change, I have to change down 2 clicks to get a change of 1 gear. When moving UP through gears, I have to select a gear, then click the rear gear shift down one click, in order to stabilize the transmission & try to prevent the chain jumping as described above.

Do i need a new chain & cassette? Or do i need to do more fiddling with the H & L limit screws - or the indexing?

Thanks if you can lend a thought!
Ray

First off, what were the symptoms _before_ you began making adjustments?

Second, what components are you using (#speeds, RD, shifter/brifter)?

Third, how many miles on the chain and cassette?

Fourth, did anything change on the bike just before the problem started (e.g., did the bike fall over on the drive side, even lightly) ?

High and low limit screws do not help with the gear change adjustment. The limit screws will only limit the derailuer movement so it will not go past the High and Low cog. If they are not adjusted properly your chain can over shift and fall between your cassette and spokes causing damage to the spokes and weakening them.
You likely need to replace the cable and housing as mentioned by a previous reply. If your not familiar with this then take it to a local shop. For $20-$25 they should have you up and running smoothly and quickly.
Here is a good link if your wanting to try it yourself
http://www.parktool.com/repair/readhowto.asp?id=64

el Inglés said:

have you tried replacing the shift cable and cover ? usually if you have trouble dialling it in , up shifts ok but not down or vice versa then the cause can be a sticky cable - and it´s a fairly cheap thing to do .

This is a good suggestion, but sticky cables usually shift down well (because the shift lever forces the cable through the guide) and up poorly (because only the derailleur spring is pulling the cable through the guide).

artemidorus said:

This is a good suggestion, but sticky cables usually shift down well (because the shift lever forces the cable through the guide) and up poorly (because only the derailleur spring is pulling the cable through the guide).

funnilly enough it can do both on an either / or basis , ususally what happens is that you can either get the up shifts ok or the down shifts but not both in sync - in any case it´s an easy thing to do and the cables and covers probably need to be changed anyway if they´ve been on the bike for more than 2 years ( active riders may need to replace the shifter cables every year ) though the brake cables can last longer , mind you their failier can be more " interesting " .

Thanks for all the replies people, i think i'll attempt to tackle the gear cable & housing...

Ray

FWIW, I recently began experiencing rear cog problems (inadvertent gear changes and less than crisp shifts). I took it to my LBS and asked them to check everything (alignment, cable tension, chain, derailleur, etc.). They changed the chain and cleaned the cassette and it is now shifting smoothly again. I had ~5K miles on the chain and I discussed frequency of chain replacement with the LBS. They suggested changing the chain every 2.5K miles, which I plan to do from this point forward.

RapDaddyo said:

FWIW, I recently began experiencing rear cog problems (inadvertent gear changes and less than crisp shifts). I took it to my LBS and asked them to check everything (alignment, cable tension, chain, derailleur, etc.). They changed the chain and cleaned the cassette and it is now shifting smoothly again. I had ~5K miles on the chain and I discussed frequency of chain replacement with the LBS. They suggested changing the chain every 2.5K miles, which I plan to do from this point forward.

RD, chain wear can vary quite a bit depending on the conditions you ride in. As a result, it's more efficient to replace the chain by checking for wear (stretch). You can check the chain for wear quickly using the Park CC-3 go/no-go gauge (about $9). It's got two sides, 0.75% and 1.0%. When the 0.75% side drops in, you can go ahead and order a new chain and replace it on your own schedule. Takes about 10 seconds to make this check, so it's easy to keep an eye on your chain.

Alternately, if you have a good steel rule, just measure between 24 links. New chains will measure exactly 12 inches. When this length has grown at least 1/16, but less than 1/8 inch, time to replace the chain.

FYI, my last SRAM PC-99 chain lasted 6000 miles before the 0.75% wear point on the gauge. As the saying goes, YMMV, based on environmental (sand,dust,rain) and lube conditions.

dhk said:

RD, chain wear can vary quite a bit depending on the conditions you ride in. As a result, it's more efficient to replace the chain by checking for wear (stretch). You can check the chain for wear quickly using the Park CC-3 go/no-go gauge (about $9). It's got two sides, 0.75% and 1.0%. When the 0.75% side drops in, you can go ahead and order a new chain and replace it on your own schedule. Takes about 10 seconds to make this check, so it's easy to keep an eye on your chain.

Alternately, if you have a good steel rule, just measure between 24 links. New chains will measure exactly 12 inches. When this length has grown at least 1/16, but less than 1/8 inch, time to replace the chain.

FYI, my last SRAM PC-99 chain lasted 6000 miles before the 0.75% wear point on the gauge. As the saying goes, YMMV, based on environmental (sand,dust,rain) and lube conditions.

Thanks for the info, dhk. I planned to order the chain cleaning kit from Park anyway, so now I'll order the chain gauge at the same time. I suppose it also depends on what kind of power one is riding at. Anyway, chains are cheap, so I don't really mind replacing it a bit early. But, now I'll know from month to month how much it is wearing. Thanks again. BTW, I graduated into the 300w FT club last Friday (315w). Only problem is that now all of my intervals have to be ratcheted up. Ugh!

i had a shifting problem that the LBS fixed by spraying WD40 in the gear leavers, then blowing with high pressure air.

seems shimano uses a grease that can cause shifting problems after some usage.😕

cu,
larryb

el Inglés said:

funnilly enough it can do both on an either / or basis , ususally what happens is that you can either get the up shifts ok or the down shifts but not both in sync

I find that one only reaches this stage after one has spent some time messing with the barrel adjusters trying to fix the problem.