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rough gear help
just after some advice on a gear roughness issue, does anyone have a problem with gears being a bit rough and crunchy when riding over rough stuff, especially at high speeds? is a problem that has plagued me for well since i bought the bike..have eliminated linkage play (fixed) suspension play, cables and housing have nice freedom to move, and has had multiple deraiileurs (3) shifter has not however been changed (x-9 shifter and med cage x-9 mech)..have also had multiple chains new cassette pg980 and used shimano xt cassette too..am running 11-34 rear and a 34 tooth front with e-13 chainguide. Have learned all active suspension only movement now leaves derailleur/shifting unaffected, however pedalling while supsension is taking a beating does create roughness and "crunching" of gears. im thinking that its the result of the derailleur itself moving about while under bumpy terrain, but is this normal? i know you should choose your moments when pedalling and not but it seems like it shouldnt be this way..any advice appreciated! oh also i dont mean while moving slowly either, you can pedal over as rough as is possible while moving at cross country speed, but while going fast at more dh speeds is where the problem comes in..
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I have found that on new bikes the chain is inevitably 2-3 link pairs too long. What this does is stop the rear derailleur from applying enough tension to the chain. This allows the chain to jump around a lot over the rough stuff, and if you have multiple chain rings makes it very easy to jump off the middle chainring and straight onto the bottom bracket shell, missing the granny ring altogether on a downshift.
Bypassing the rear derailleur (for the sake of the exercise) you should only have enough chain on your bike to complete a loop around the big front chainring and big rear cog, plus 1/2-to-1 chainlink pair.
This advice is included in the instructiosn for every replacement chain I've ever bought, so I don't know why it seems to be ignored on every bike I've ever bought!
This might not be your issue, but it is worth eliminating as a cause. I used to have a lot of trouble with the chain wrapping around the BB until I woke up to this.
Speaking of which, I'd better go check the chain on the hardtail I just bought off ebay...
well i have had a few chains on there, the last installed by the lbs., but yeh i guess removing a couple of links couldnt hurt to see..chain tensioning does seem to be a plausible factor..its hard when you have multiple causes to isolate all of them.. i only have a single front chainring with chainguide, but as you can see in this pic taken a year ago http://nobmob.com/node/2986 the chain is very wonkey under full compression, making me think when fairly active under repeditive bumps, pedalling would not be good..so im thinking perhaps its the nature of the beast? but does anyone else experience this problem at all? particularly those with bikes with a faux 4 bar style linkage etc
Have you ever heard of the expression chain growth? It's a commonly thrown about marketing phrase which attempts to explain why that particular firms suspension design is so clever in causing the suspension to allow the rear wheel to move back as well as up in an effort to get over an obstacle.
Actually it's all a load of nonsense.
The chain doesn't grow. Distance between the bikes main pivot (which would be the instant centre on a linkage bike) and the rear axle increases as the suspension moves through it's stroke. This increase is very small and the biggest I've heard of is 28mm on a Santa Cruz V10 which has 254mm of travel. Also the instant centre moves about on linkage bikes. These types of bikes with less travel have less change.
Most bikes don't work like this. Your bikes suspension causes the distance between rear axle and pivot to decrease and this is common with many bikes. The decrease is very small yet is happening all the same. This is because the design of your Session (and others like it) relies heavily on constant chain tension in order to pedal well whilst remaining active. To increase that distance between axle and pivot would cause over tension at some points throughout the travel. This is commonly referred to as pedal kick back. This is where correct chain length comes in.
When your chain sags then the spring tension of the mech needs to take up that slack. If you are in a tall gear and hit a rock garden at speed or land a jump causing a lot of compression this phenomenon will be amplified. Look at photos of some folk landing and the massive slack in the chain. The mech is unable to take up the sudden slack.
Solutions; Possibly a shorter chain. The crunchiness you report would be your chain attempting to fall off and being held in place by the guide. However it still loses engagement on the cassette.
You need to discover the ideal chain length for your bike relative to the ratios and mech used without it getting too short which would be distastrous for obvious reasons.
Sram mechs and the Shimano Shadow mechs don't flap about like conventional type mechs, which is why they exist and are so popular. Your mech is attempting to take up chain slack that it cannot. I doubt your X9 mech is a problem here.
Many people seem to have an overly long chain. This is an observation I've made over time. I've learnt that bike shops or their suppliers supply bikes like this to prevent the idiots returning with a broken rear mech and/or mech hanger after riding around in the dog and big rear sprocket combo and then landing a one metre drop at their favourite track. The first thing I do when I buy a new bike is strip it and check it over thoroughly and I always have to shorten the chain upon reassembly. Correct chain length is critical to correctly functioning rear suspension.
This could be your answer. Or it may not be...
hmm that sounds like very likely thanks mate, ill try anything! so should i take the previous post length guide on board given this circumstance? or just remove a link and repaeat till problem goes away? how do i know what is too short? should i just bypass derailleur run it over big rear cog and front and make that minimum? or plus 1/2 to 1 pair ontop is minimum no matter what? cheers!
... One bite at a time.
Learned from too long spent racing go-fast toy cars: the only way to isolate the problem is to fix the problems you find, one at a time, until the unwanted behaviour is solved. Good luck with it, and let us know what you find.
Edit: try to get your suspension to the point in the travel where the chain length is the longest (could be min travel, max travel or somewhere in between, depending on the bike) and then set the length as I've described with the suspension in that position. That will guard you against breakage.
If you're going to go trial and error, you'll know it's too short when your chain snaps (ouch!).
Sell the Shrek and buy a Cannon
ah Im funny , told you that was coming mate payback is a bitch.
yes speaking of bitches i ran into your mu...no i cant get that low brow here lol
hawkeye, delicious, i owe you guys a nice big beer that seems to have done the trick! my chain is about 6 link pairs longer than a loop around the big and front cogs! i took out 3 and its running better already, is it right i can go right down to 1/2 to 1 link above the loop? that seems small, is that risky? does my chain only gain slack under suspension load or would it stretch at points too?..cant belive i never thought about that..actually both new chains were put on by bike shops and i assumed they would have done it properly, but it does make sense they would give more then less slack so u cant blame them for damage.. is definantly a combination of things, but now my re-routed derailleur cable doesnt pull anymore, and the lower pivots have no more playthat and the chain, hopefully i maybe able to ride a fully functional bike again! *touch wood!
but seriously thanks heaps guys it took 3 bike shops and a year and noone even suggested chain length might be a factor..
is this more a problem with 4 bar style linkages? seems chainstays that dont alter under load such as specialized etc might not suffer from this problem? i know its a risk even putting a chain on a cannondale much less a rider
Bike shop guys are an odd breed. They tread a fine line between giving creative advice that's outside the square type thinking which they know damn well is useful and being sued for creating a situation which is not endorsed by the bike manufacturer which then goes pear shaped and a rider stacks and attempts to blame bike shop guy all the while pointing his finger at said bike shop guy claiming the modification was all his idea.
I've said this many times. And I'll say it again. Correct chain length is crucial to correct rear suspension operation. Absolutely critical. No matter who is the manufacturer. No matter if the design is a true single pivot with a direct drive shock or an FSR type four bar or a dual link type with a virtual pivot, regardless of which way the links swing. I can assure you that the designers never meant for the finished bike to be supplied with a chain that is too long. It is unfortunate that guys like Joe Graney and Jon Whyte aren't the same blokes building the bikes we ride. Otherwise they'd end up set up correctly.
So then Alex if your bike rides along nicely don't mess with it and for heavens sake don't make the chain too short. Your chain only slackens under compression yet returns to an even tension upon rebound. And I hope you have your suspension set up correctly as sag needs to be taken into account for all this also. Anyway as I said if it rides nicely and you don't feel a tugging at your pedals then all should be ok.
Now Alex onto other matters...
You seem to have a beef with the corporation known as Trek. You need to relax. Why? Well what were you doing with your eyes when you bought your bike? That rocker was always going to hit the seat and a qr seat clamp was definitely going to gouge it. What did you think that banging sound was mate? Did you not pause to address these issues? The Session bikes had some flaws which is largely why they were discontinued. Ditto for Liquids and Remedys. Ultimately you have been stung for buying a bike that was sitting for years doing nothing in a showroom. Your brake issues spring to mind.
Trek aren't a bad bike company. Clarence St isn't a bad shop. Overpriced yes. Bad, no. The new Treks with the ABP and full floater work well and I'd happily buy one however I'd never buy an early production anything. It takes time to work the bugs out of the manufacturing process. Early production new Fuel EX have been breaking. I'm confident that this will get sorted and you are the only guy I've heard of to have a problem with Trek warranty.
Now to Cannondale. I do realise that a bit of friendly sledging here and there about brands other than a personal favourite is tons of fun. Yet Cannondale aren't bad bikes. The problem here is that some people buy one and expect big things out of it. Some bikes, such as Konas are renown for being extra tough. Others are only as tough as they need be. So don't buy a Rush and huck off big ledges with it, over and over and over again to then slag off Cannondale when it breaks.
I'll stop there...
yeh look mate ill always bash cannondales just for fun because its silly and people often take themselves and their riding far too seriously in my opinion and theres nothing like a good cannon bash to make the day a litlle lighter
i actually think cannons are a reasonable bike and the designs in the past have been quite good (delta v's etc were tops back in the day) i do think 10k for a 7" freeride "carbon" bike is dubious and ridiculos but thats personal opinion..
as for treks, i speak from experience so thats why im pissed, those who remember will know i was super happy about the trek when i got it, loved the look the design and everything about it, and actually, i still do, regardless of my issues. clarence st are not a good shop sorry, they have been unhelpful in my problems, unknowledgable about all of my issues, or simply careless, and even accused me of braking incorrectly hence my previous brake failure. yes it was on the shop floor yes it was discounted, but it was a new bike purchased for good money, and when the issues came up, they didnt want to know. seriously i argued with 3 mechanics all telling me that when you hold a brake lever on its supposed to fail..i shit you not.
so is poor design my fault? should i analyze all the functionality of a bikes linkage before riding it? im not an engineer, but if the the clamp doesnt fit through the linkage it shouldnt be on the f&^&ing bike! lets not forget they gotta 6.5k retail on these bikes they should at least know that the clamp dont fit..and yes of course i paused, i thought the bike was bottoming out violently and the few times i sat on the bike caused the gouge, god help me if it took longer to find out. and furthermore, bypassing clarence st as everytime i call them about the issue they claimed was covered by warranty, noone knew anything about it and gave me the run around..contacting trek by email returned no response whatsoever.. ..as for the brakes, they tried to fix that problem by selling me some out the back juicy 7's "discounted" just for me for 700 a pair..not a good bike shop at all mate.
i like the treks and i like the new ones too, and i would buy one again if the price was right., do i like trek? no i dont i have had more help at tbsm and on line that i drive 30mins to get there just because they actually try to help me and not rip me off, which counts for a lot when u get nothing but a headache from the company and distributor that sold it to me..
I had no clue you were treated so badly. And I don't suggest you are to blame for a design flaw. I find it incredible that bike shop staff can be so useless. I'm glad you still like your bike, Alex because it's a shame when I hear of issues such as yours. I still get about on my Liquid after all these years and even though my other bikes show up it's limitations I still enjoy it.
I'm pleased you like TBSM because I also think they are a top shop.
As for your brakes. I have some pretty strong opinions on this sort of thing, so brace yourself. Those brakes should never have been there in the first place. They are not a downhill brake. Neither are Juicys. You have been wasting your time and energy fighting with a bike shop about it. I know you don't want to hear this but a warranty isn't going to help with a bad product choice. You can go around in circles banging on about what product should be fitted and what shouldn't be. If it were me I'd have removed those brakes the day I brought the bike home. And replaced them with a more suitable one.
My Glory for instance. The oem brakes were Juicy 5. Not a bad brake. Work rather well. A downhill brake? No way. Did I go harrasing the bike shop about it? No. Being a bike rider means one has to take a certain amount of responsibility in how their bike functions. I didn't like the oem brakes so I changed them. I now have Hope Mono M4 which are excellent. It doesn't matter which brand you choose. Just choose the correct model. It has often baffled me the horrible choices that product managers make when speccing a bike. Quality brakes are so important. I'd rather put money into brakes and have a lower spec transmission any day. I didn't like the oem transmission so I changed it. I didn't like the oem bars and stem, seatpost or seat. Or tyres. So I changed them. Not really happy about the fork either and that's next on my hit list. Yet I have better things to do than create havoc at the bike shop about the foibles of how my bike was presented in it's stock format. Actually what really makes me cranky is the inability to purchase a Giant frame only in Australia. Or other big brands for that matter. I'll avoid buying a complete bike ever again. If possible.
You see Alex, you've got yourself into a past time which is ripe for customization. So embrace that and get the very most you can out of that Session because I have ridden one once and they feel rather nice. I doubt that you have even scratched the surface of what your bike is capable of. I have a fair idea of the parts pick on your bike and I can tell you it's pretty bloody jane. So for goodness sake do yourself a favour. When something on your bike fails (provided it's not a weld) then don't go running off to Clarence St with all guns blazing about your warranty. Just replace that item with something better. A lot better. And lighter. And perhaps in a nice colour (Hope make brakes in pink y'know...) And then you'll end up with the best Session in town.
Why use a gun when you have a Cannon
Ahh Im so biting my tongue right now
See you at OXY on Monday mate , Ive got a spare bike hanging around here if you need to borrow one .
yeh i hear u mate but i dont think u get my point, the front brake failed after only weeks of purchase..im talking major failure, like pull the lever brakes grip, then loose it..it caused a big crash. there was something clearly wrong with it and it should have been replaced. but i was told it was my fault (??) so after bleeding attempts which i paid for, then a new master cylinder and hose which i paid for, the problem was still present..they were faulty is my point end of story..i replaced them now with code 5's and couldnt be happier. but remember many people ride with hayes mags and have had no troubles..as they should, its not a question of how good a brake they are, its a question of a faulty product..turns out there were a few faulty products on the bike, such as my fork i just found out, but its now a boxxer (thanks dave!) but we wont go there
Fair enough mate. I want you to know I didn't set out to attack your mtb wisdom. And you're right, I was missing your point. I didn't understand how quickly your parts failed and how poorly treated you were. Let's move on...
If your bike is in good shape now then tops. If you have any issues with any parts then look for your answers here, among fellow riders, not at a shop. There's always a place for a good shop in all our lives (TBSM and Maroubra Cycles come to mind) yet it's ineffective to rush off to a shop for every little problem. I point to your long chain issue. I reckon a lot of shops would hesitate at shortening a chain for reasons I've mentioned.
Just one last thing. The next time you buy a new bike, don't buy a discontinued model that's been sitting on the shop floor for three years. Any faults in the brakes or elsewhere can be attributed to those parts not being used, the fluids not moving about within and so on. A bike that you wish to operate safely and securely every time you come in for a landing is not the place to scrimp and save. Quite often you get what you pay for.
But you already know this, don't you Alex.
I like some of the points that have ben raised on this thread:
Like relaxing.
And pausing.
And opening your eyes was a great point that was mentioned earlier.
Alex, if you had relaxed, paused and opened your eyes during the test ride of your session on the dh track at clarence st then you would have noticed the banging sound. I can't believe you would think one of the biggest bike companies in the world would build an expensive bike that didn't have flaw in the suspension design, and I can't believe that you didn't take your engineer with you to find this.. IF ONLY YOU'D PAUSED TO OPEN YOUR EYES!. And relaxed.
Alex. I'm concerned that you have not scratched the surface of your bike's potential. Because that's what it's all about to me, scratching the surface. But not on a cannondale because the f'er will break. Jokes, I love cannondales. They make my bike look more masculine.
I love bike shops like Clarence St too, who not only offer free vitamin K and amyl nitrate coctails with every bike purchase so they can ____ ___ __ ___ ____, but they also put on the sales charm to shift stock, then act like they don't know you when you chase up on issues that they are obligated to help you with. But they are not a bad bike shop, they are just shifty mother f$ckers with no ethics. But they are a good shop. A great shop.
When your bike breaks, don't take it back to the shifty pr!cks who jibbed you, what you should do is pay more money that you really could be spending more wisely elsewhere on new parts that should not have broken in the first place.
Just one last thing. I want you to embrace being ripe and cutomise bloody jane. But you already know this don't you Alex? Or is it the oracle that knows it? I'm confused.
well yes but we asked the guy when it was looked at what the 2008 model would be like and whether the frame would change and he said it was going to be the same so i had no idea it would be discontinued until the 88's reared there head, in fact noone did. i agree one shouldnt skimp on such things where poss, so i avoided a 2nd hand bike. But some of us cant drop thousands and thousands on bicycles and swapping parts that we dont like as much just cause we want something a bit better or lighter, is a bit extravagant for many! but let me remind you a couple years inside a shop aside it was still a new bike, with top of the line specs, and its their responsibility to make sure the bike is still fit to ride as its in their care till you buy it, and its sold as unridden, just like a car would be.. they slapped the 5 year parts lifetime frame to help sell it (which i later discover does NOT apply only to the session which gets 3 years, although i was told lifetime) and what parts are we talking here? cause ive replaced em all, and all are apparently not covered, in fact id love to know just what is covered..and if they were, id prob die of old age before i got them~! anyway whatever dude its all good, i still got a kick ass bike for nowhere near retail, and so did lee (who has had none of my troubles!) and even with the 2k ive had to put into repairs, its still a couple of grand less then retail, but seriously you would have to be a retard to drop $6500 on one! I just hate it when people dont honour their agreements, and screw you over..it really, really shits me!