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frameflex = chainslip ?
recently my scale hardtail has started to either slip or even drop the chain under full load. It only happens in the middle chainring at the front and and 3(sometimes 4) up from the bottom at the back.
it usually only happens on rocky stuff when out of the saddle and pushing hard, like lifting the front over a rock or something along those lines. Occasionally it'll even drop it down to the granny ring which then results in a nasty OTB and knee to the handlebars incident. The fact that it's dropping it at the front makes me think it's also slipping at the front and not the cassette.
So, over the last couple weeks I've tried new chain, new chainring, new cassette and any combination of new and old that seemed to make sense. Have also converted the rear to a thru-bolt which is nice but didn't help with this problem. Shifters and rear are X0, FDR is XTR. That combination has been working fine for ages up to now. The frame is a 2006 scale carbon.
oh, and I can replicate the problem even on the road if I go uphill and really force it.
Any help would be much appreciated.
Thanks
S
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What brand and type components are you using? When I got my cannondale I had a similar issue and replaced the chain with an XTR (i think it had a KMC fitted) and fix it.
could your chain be to long and not have enough tension when in middle ring?
My Trance came with a chain too long. I know you shouldn't run small:small gears but check out the slack below. Using the big:big method I had to remove a link or two
Check your cables. They might be stretching or flexing when you do a big move which will cause the gears to jump. Sram is better than Shimano in that regard as Sram needs twice the cable movement compared to Shimano, which makes it less susceptable to cable issues.
hi guys,
thanks for your input, really appreciate the help.
below is the current setup.
I was suspecting the rear derailleur for a while as it is getting quite old now. did replace the jockey wheels not too long ago though.
as for the chain, i tried it with one link less but it didn't make a difference, also couldn't shift into big/big anymore (not that i would).
the only other thing is that i've been running this setup for quite some time without any issues. when worn out i usually just replace drivetrain components with the same model. i.e have been through 3 or 4 PG990 cassettes on this bike. same for chain, etc. and yes, it still happens even when the whole drivetrain is new.
come to think of it the only change in the setup is that i switched to goodridge cables couple month back. about the same time these issues started ... hmmm ???
cassette: SRAM PG990
chain:SRAM PC991 Hollow Pin
Rear:SRAM X0
Front:XTR (the bottom bracket version)
Cranks:XT
Chainrings:FSA and XT
Cables: Goodridge outer and inners
Did you replace the cable housing?
Ive had similar issues with old worn cable housing.(with new cable)
Hope you get it fixed.
Make sure you do cables and housings at the same time, also check the internals of the shifters and clean'm out
Speaking of frame flex, you dont have a crack in it, allowing for unwanted movement??
thanks guys, nope, no crack in the frame. but it hasn't had an easy life and there is fair bit of flex around the bottom bracket area.
i did put new cables and housings on. now thinking i might try replacing them as it would be fairly cheap and easy to do and i find the goodridge housing to be a little too stiff anyway. (you can feel it restricting the steering)
not to mention that it's the last thing i haven't tried yet and i seem to be out of options otherwise.
guess i could try a different brand chain but don't really want to go there as both the chains i'm using are still at a 100%. (i alternate them)
... ?
Just do the cable to start with for sure.
Don't be fooled into running full length outers on the cables. It just adds to the friction.
Stefan, there is likely a solution to your problem that will only be solved via a non readily available commodity .... experience. The problem that you speak of, I have encountered multiple times before on many different setups. Often it is very fixable.
There is alot of advice being given here that I'd say 80% of the time would be useful. There is also plenty of folks dispensing advice that likens itself to going shooting with a blindfold on or just pissing into a stiff breeze.
So my advice would be consult a paid professional before the fore-mentioned "nasty OTB and knee to the handlebars incident" happens again and you toast either yourself or your frame when you bin it. Could be kinda costly and ouch.
Doctors are there for fixing people
A chippie builds houses
Car mechanics fix cars
A baker bakes cakes.
Kim Kardashian makes videos....
You get where I'm heading. I'm all for learning and havin a go but if you run out of solutions from your current sources of info maybe time to seek a paid professional.
Cheers Brother
Fank
How old is the chainring?
I had to change mine last year due to the exact problems you have described.
@ fankles... couldn't agree more, and since I've now officially run out of DIY solutions it is in fact time to seek professional help. (just did a trial run around the house with new FDR cable and that didn't fix it)
Unless someone here wants to recommend a shop for this i was going to pay mc cyclery in the city a visit... They've been good to me in the past. Just wondering if this might be too specific for them.
Any recommendations?
Thanks
Hmm, hard tail so no suspension to pull the cables. New chain, ring and rear cluster so teeth & chain should be ok. Cable, ok, poor shifting maybe but you can iron this out with the adjuster...
My money would be on the rear mech not putting enough tension on the chain to make it wrap around the cog OR a too long chain causing the same.
By the way, I have had problems like this mixing Sram & Shimano chains & cassettes and now use one or the other. The chainring is less important as it has so many more teeth but the back end is definitely slicker with the same manufacturer.
Good luck
T
You should go to the Maroubra version of MC. The mechanics there are better.
So I hear...
Heres 2 cents worth - not in any specific order.
1) mixed systems - use same chain manufacturer as rear cassette
2) rear Der spring isnt broken or weak?
3) rear der has full movement and no tight spots?
4) chain has no tight or kinked links? (can occur on new chain tho rare)
5) chain line in gears where problem experienced - is it straightish?
6) front rings are true and no bent warped rings/teeth?
7) BB is tight and free running?
8.) middle (Standard?) ring, does it flex under high load?
9) Can you check your BB for flex when stationary, put full pressure on pedals while someone holds the bike?
10) All bolts on any part of the cranks, gears, rings, derailleurs, etc are torqued correctly?
11) chain rings are sitting on the spider correctly and run true?
12) Both Ders are aligned and adjusted correctly
13) no cables are caught anywhere or pinched - are all cables loose when at both 'full lock'? Also the end caps are seated properly - no cable compression?
14) rear sprockets run true, no bent teeth - especially on those where problem occurs?
And Midland Cycles has good mechanics
Hostile Monk .... One of the most comprehensive yet. Top Marks
Still one more thing it could be that does overlap three of your suggestions.
Certainly on the right track though....
The cream is rising to the top.
Guys,
1. SRAM chain,cassette and Der.
2-4 tick
5. Straightest gear I've got. Although it's probably the slackest gear that cops full power.
6. New
7. 2 month old - all good
8. currently running a new FSA ring but same problem with a shimano XT ring. No visible flex
9.yes, there's a bit of flex in the frame around the BB
10. Tick, even put new chainring bolts on to see if that would fix it.
11-14 tick...
Now, while checking everything today, I did notice the B-Screw was tighter than what SRAM recommend, so the rear der. was sitting too close to the cogs. Haven't had a chance to ride it after fixing this up.
Will let you know if that fixed it. Otherwise it's back to plan b - the shop.
Thanks
Did you replace chain, ring and cassette all at the same time, or was the old ring on the cranks for awhile before you replaced it?
Reason I ask is a worn ring with a new chain can stretch (wear out) a new chain quickly. You then put on the new chainring and the now-stretched chain either wears out the new ring, or slips, or both... same deal with not changing cassette and worn-out chain at the same time.
The fact your transmission slips in the middle of the cassette is a clue that wear could be a factor - these are your most commonly used ratios.
Unless you catch your transmission wear before the chain reaches 0.5% elongation you need to replace the whole lot - cassette, chain, chainring - at the same time. Big dog can usually be left as it doesn't get that much use or force compared to the middle, which gets a flogging.
I run three or more chains in rotation per bike to get the best life out of my cassettes and chainrings.
Hope it is the B-screw (i.e. #12) Both Ders are aligned and adjusted correctly). let us know the outcome plz.
IF it isn't fixed, I'm suspecting (hopefully I'm wrong) the least likely and most costly, a frame issue, Check your warranty (and health fund).
1)a flexi frame thats got more flexible with age/damage, unlike us humans that get less flexible with age and damage! If you get frame flex while stationary then I suspect you may get more when really honking on those pedals.
2) Alternatively you may want to check for a frame twist, but doubt that on a Scale Carbon, but it is 5 years old. Are the wheels inline top and bottom?
3) Are there any cracks or damage to the frame? You mentioned an OTB incident (or Arse over t*t as it used to be called), is there any damage to the paintwork. Damage may be almost invisible but is likely if you've had a number of offs over 5 years.
4) there is chipped/damaged paint work or exposed carbon on the frame resulting in water absorbtion.
Just a point from the other post on torqueing up the various components. Over tightening (over torqueing) carbon frames/components is probably the most common way of damaging carbon frames, probably more so than crashes. For example where the front der clamps to some downtubes, excess torque may damage the frame. (Buy a small torque wrench
)
Caring for carbon see for e.g. = http://jimlangley.com/articles/caring-for-carbon...
Also can't see a mention of frame size or your weight. IF (stress IF) its a large frame, and you are heavily built and therefore very strong, then frame flex could be an issue and more likely if damage to frame.
Some more "by the numbers"
5) check the rear hub isn't loose or has some side play
6) Rear wheel spokes are correct tensioned all way round and the wheel is dished correctly.
7) (going back to the BB/crankset) - it does have all the spacers on it and in the right place? (soz if this sounds like I'm teaching you to suck eggs)
8.) You haven't had chain suck and 'sawn' into the BB?
Let us know how it goes and good luck :/
Your freehub may be slipping. Full of crud or lack of lubrication, the palls will not engauge properly and fail under load.
Just wondering if Stefan sorted his slip issue
I,ve go a simmilar issue with my hard tail just now I have two sets of wheels and one rear works fine so i'm sure its not a bike issue, but the SLX Hub apears to be slipping as soon as i lean on it. Does any one know if this can be fixed or do i just get a new free hub. Strange though as it only started after I serviced the bearings,(I've checked them several times and never had issues before,the free hub seems to be held together by the inner race, so would i need to dismantle this to access the mechanicals of the Hub(i removed the free hub no worries
Think i'll drop it in to a Bike shop this week, nice to see all the new toy's anyhow
@Darran: have you chnged the cassette when swapping wheels over?
Cassette wear is a common cause, so I'd suggest putting the cassette from the wheel that is *not* slipping on the wheel that is suspect. This ensures it is only the hub that changes and isolates cassette wear out of the picture.
worn freewheel with play is often a culprit. grab the rear casette see if you can move it side to side, if yes, bearings in freehub are gone, it if a leading brand of hub, you will be able to replace the freehub, if no play, well, everyone else has chimed in on some of the other possible causes.