Gears skipping under a load

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Gears skipping under a load
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flag tortoracer
Posted: Oct 10, 2011 at 18:05 Quote
I have noticed when i pedal up-hill in a high gear (heavy load), i have a problem with my gears grinding without any shifter movement.
the problem is not only up-hill, but nearly always while in 9th (top) gear.
My derailer is adjusted perfectly, so i am quite confused where the problem lies.

in the front sprocket, there is only one gear, so it is a 9 speed bike. the chain might have a small bend, or the cassette might have small tweak.

what does it sound like to you?
flag ezekiel
Posted: Oct 10, 2011 at 18:12 Quote
When was the last time you replaced any of your drivetrain components?
flag tortoracer
Posted: Oct 10, 2011 at 18:17 Quote
I bought the bike used about 3-4 months ago. I personally have only adjusted the derailer, so as for replacements nothing as of yet.

it is an ironhorse 7point3, and as far as i know stock drivetrain, except for only one sprocket in the front.

(cranks always loosen up, joy

only thing i am really looking for right now, as you cant see the bike right now, is what to check in detail...the chain? the cassette? the derailer?
flag RotoruaFreeriders
Posted: Oct 10, 2011 at 18:57 Quote
there could be lots of dirt\gunge in the cogs at the back. eather that or it needs tuning. it is probly muddy though
flag tortoracer
Posted: Oct 10, 2011 at 19:16 Quote
tomorrow i am probably giving it a minor tune-up, lube the chain, hose it off, etc.

should i take a bit of brakekleen to the cassette before i lube it? what is the lifetime of a chain? of a cassette?

i am new to this, but mechanically apt, and willing to learn it all.
flag kent
Posted: Oct 10, 2011 at 20:06 Quote
the life of a chain/sprockets will vary greatly

if you ride in only dry conditions and lube it regulary it will last a LONG time

if you ride in the dust/rain/mud and couldnt be bothered to clean and lube it expect very short life out of your drivetrain

i clean and lube my chain after every ride in dust or rain
in dry conditions every 2-3 rides for 5 min of time and a $5 bottle of chain lube a year its cheap easy maintaince and skipping gears will drive anyone crazy
flag tortoracer
Posted: Oct 11, 2011 at 6:12 Quote
I don't think I ride where there is too much dust/mud etc. But I am talking about stretch mainly. The last chain I had stretched over like the 3 years I had it. Could that be it? And yeah I definately gotta lube it.
flag superbikes
Posted: Oct 11, 2011 at 6:35 Quote
id say its your cable moveing when under heavey loud fullsus can pull the inner cable makeing your gears skip . i had this problem try moveing your cable about to account for the travel moveing . it dont pull your inner cable when your travel goes down it pulls your inner cable when travel is returning . Have a mess with it im shor im ryt . But could be wrong to
flag Khreat
Posted: Oct 11, 2011 at 11:20 Quote
I'm learning too, and have had a few problems with skipping gears, mostly due to my inexperience with bikes, despite being quite mechanically minded.
Most recently I had a 9speed cassette with an 8speed chain (different sizes).
If it's a used bike, and possibly been used mostly for commuting, 9th may have the most wear, and the chain is slipping off the teeth under high torque.
Chain is quite possibly 'stretched', read the tech tuesday post about checking your chain. It's easy to do and you only need a tape measure/rule.

Hope this helps
flag camerondodd98
Posted: Oct 12, 2011 at 13:31 Quote
I had my hardest gears slipping in a wet as race. Its just that the cassete gets clogged with mud
flag tortoracer
Posted: Oct 15, 2011 at 18:14 Quote
thanks for the help guys, im going to go for a guess and say it is the cable moving about etc.

i plan on checking the chain for stretch, and just a general look-over, thanks so much guys Smile
flag rolto1822
O+
Posted: Oct 15, 2011 at 18:46 Quote
If it's slipping, it's likely a worn drivetrain. being that the bike is used anyway, i'd replace the chain and cassette. Check the front rings for wear as well - they should all be the same shape and size, and shouldn't look like waves or sharks teeth.. If you replace both the chain and cassette and it still slips, you should change the chainrings pretty damn quick. If you run a new chain/cassette on worn chainrings you'll just kill the chain and cassette stupid quick because it prematurely wears down those components.
Cleaning your drivetrain should involve some form of degreaser or strong detergent (muc-off will do) because the gunk that gets on and in your chain/cassette etc. won't get properly washed off with normal hosing/whatever. degrease, scrub until clean, let dry (or wipe with clean cloth), small spray of GT85 (displaces any water left in the nooks), leave to dry or dry thoroughly with a cloth, then use a proper chain lube suited to the conditions you ride in.
This'll prolong the life of your drivetrain.
Skipping (ie. when it's trying to get onto a different gear) is a different matter and is more likely caused by poorly set up derailleur/bent hanger/snagged cable/dry or rusted cable.
flag scottvt
Posted: Oct 15, 2011 at 18:54 Quote
Another suggestion is that your chain is too short. When in the biggest cog in the rear, and obviously only one ring in the front is going to take up the most length of chain. When the bike is at rest, what does the rear derailleur look like? It is pointed towards the front of the bike at an extreme angle? If so, when your suspension compresses, (which will make your chainstays "grow") you need a little slack in the chain to make up for it. Put the chain in the big front big rear combo, take the rear shock off, and cycle the suspension, and see what happens.
flag rolto1822
O+
Posted: Oct 15, 2011 at 19:06 Quote
scottvt wrote:
Another suggestion is that your chain is too short. When in the biggest cog in the rear, and obviously only one ring in the front is going to take up the most length of chain. When the bike is at rest, what does the rear derailleur look like? It is pointed towards the front of the bike at an extreme angle? If so, when your suspension compresses, (which will make your chainstays "grow") you need a little slack in the chain to make up for it. Put the chain in the big front big rear combo, take the rear shock off, and cycle the suspension, and see what happens.
Good point, was thinking that assuming its the original drivetrain though, it should have been properly set up at the shop. usually if it's loose enough to skip i'tll actually visually sag a bit compared to how it should look.
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