How To Fix Your Mountain Bike Gears | Stop MTB Gears From Skipping

usually on our ask q a session we answer all your questions about bikes but we're noticing we're getting loads of specific questions from lots of you about very particular things so today we're going to spin things around a bit and do an ask special all about adjusting your gears and finding out how things are going wrong do your kids skip are they under shifting are they overshifting are they going over into the cassette is it taking its time going down the block any of those questions they're going to be covered in this video and hopefully you'll get your gears working a treat despite the fact you have an external transmission on a mountain bike when they're working your gears are absolutely fantastic the problem is all it takes is a hit of a derailleur or a bit of misalignment or something not quite right and your gears will be all over the place we're talking gears that skip a bit of ghost shifting perhaps if your gear is changing gears when you're not even using the lever there perhaps your gear is not coming back down the block again it could be because your cables clogged up with gunk any number of things now in this video we're going to work through each one systematically so you can trace any issues you might be having right let's get started by having a check of the hardware first [Music] so the first things first is you want to make sure that your chain your cassette and your sprockets and of course the derailleur are in good working order because common sense dictates if there's any issues here this will translate as poor shifting now something that every mountain biker should try and own is a chain wear checker now there's various types on the market this one's a kind of workshop spec one they're a bit more expensive but to be honest even though they're more accurate you don't really need one like this these pressed steel plated ones are super simple they're cheap and they will save you money in the long run now use one of these by literally inserting it into the chain itself and it gives you a reading of how worn the chain is or how one it is not basically it's got a little key on there and it tells you when to replace your chain now in an ideal world you want to replace your chain before it's at the point when this tells you it's worn and the reason for that is you get a phenomenon known as chain stretch now metal plates can't stretch that's not physically what happens and it's actually a bit of a misunderstood uh phrase i guess you'd say so you need to understand the what makes up a chain to get your head around this so you have the pins that go through the middle you have the outer links you have the inner links and you have that roller that's on the inside there that's effectively a bush now what happens is as the chain moves around as it's being used under torque those rollers actually sort of bed out on the inside and the whole thing gets a little bit baggy and the pitch of the chain which is the distance between those pins it stretches very slightly so it's not the plates moving it's just the play in the chain enabling it to get slightly longer the effect this has on the rest of your transmission is actually quite detrimental so if you look very closely at any number of the sprockets you'll see that this roller is supposed to sit perfectly in that trough as soon as everything gets a bit stretched it starts wearing the wrong part of those sprockets and then accordingly those sprockets will start turning into little spiky teeth and you won't have the traction from the chain and then of course your shifting is going to start failing now it's up to you how often you want to check this out how often you want to replace these things but you can get two or three chains if you're vigilant to one set of sprockets at the rear and if you look at the price of the sprockets on your bike depending on what they are you'll know that this makes sense so get yourself one of these and check your chain next up is a bit more common sense so having a look for any damage any missing teeth and things like that the same applies to the sprockets on the front as it does on a cassette but something to not well something to be mindful of is the profile of the cassette teeth themselves now the shifting ramps in particular on shimano's cassettes they're a bit more prominent you can see on other brands they're designed to hook the chain up onto the next pocket and to help pull it back down again now if you look closely it almost looks like there's a few damaged teeth here but you can tell that they're not because they're part of a profiled shape that works between them all in order to hook that chain up so just don't confuse them between damaged ones you could definitely tell when a cassette is warm because it would be uh they'll all be warrantied rather than just having a few here and there but if there's teeth missing completely then you may need to replace your gear now the next step of course is to actually look at the rear derailleur have a look at the sprockets on the bottom here see if they actually rotate freely they should be nice and smooth if there's any grit any sort of grittiness to them or if they're not rotating the chain won't pass over them and again that's going to translate to your gears not working so a bit of common sense really give your drivetrain a little bit tlc and then you can start seeing what's working and what's not [Music] okay so we've had a bit of a hardware check the next thing is to make sure everything's actually in line it's all fully aligned and the derailleur is actually fully mounted to the frame as it should be now if you look up close here you have your derailleur hanger bolt so it's typically a five millimeter sometimes a torx t25 and that mounts this to the hanger that's part of the frame now the way the hanger mounts to the frame differs on certain bikes on bikes for the quick release you'll find it often has just a bolt or maybe two bolts to hold it on so check those if like this bike your bike your bike has a bolt through system it's gonna be intrinsic with that so whatever system you have make sure that the hanger itself is straight and make sure it's solid now you can check the alignment of it by looking at the gap here between the smaller sprocket and the hanger itself you want to make sure that that's completely in line that's a good gauge of reference without having to have expensive workshop tools now if it is bent you will need to bend it back now if you're unsure about this definitely take it to a bike shop or someone that has a derailleur alignment gauge especially the tool especially for doing this but if you want to do it yourself an adjustable spanner with the derailleur removed you can straighten these back but go very easy on it because you don't want to snap the thing okay now the next one is to make sure that the actual hanger bolt itself is tight because naturally these can unwind themselves on bikes if they don't have thread lock on them and you've been riding loads of dry rocky trails for a long time they can back out slightly so if that's happening that all affects the alignment of the derailleur now finally you want to make sure the actual lower cage is completely in line with the sprockets so check this on both your lowest gear and your highest gear so that is the biggest sprocket and the smallest sprocket and use line of sight from the back of the bike now if your bike's got really large tires you might struggle with it on the biggest sprocket here but you can normally get a good indication if the derailleur is in line or not if it's not then well it's bent and it does need a bit of work on it now if your lower cage is bent slightly the major thing is to make sure it can't get dragged into the spokes at all because a it can snap the derailleur off it could damage your derailleur hanger and it can ruin spokes as well i can snap them clean out the wheel of course that's going to be an expensive repair so do take care of that you can bend the lower cage back by hand but you've got to be careful doing this because it's easy to go too far so if you're unsure about this definitely time for a trip to the bike shop now the last thing to check is the cable routing itself make sure you have a good route from the shifter at the handlebars all the way down to the back of the bike you want to make sure that the the cable itself isn't too like too short and you need to make sure that the ferrules are actually sat into the stops correctly now on my bike i've got basically a constant length of outer cable that runs from the shifter inside the frame and all the way to the bottom here so the only one i have to check is this one here now if this pulls out slightly then under pressure when you're trying to change into a lower gear let's say bigger sprocket it's going to move around you're not going to get the gear shifting you need so make sure your ferrules are in but your bike might have external routing and it might have several cable stops on there with lots of different points at which the outer cable sits in so check all of those stops and make sure the cable is sat in the last one to check is the actual derailleur cable here the way it actually bolts on check the orientation this because it's super easy to have this going the wrong way and yes the gears will work but they will never be quite perfect so you can see here it just goes around a little a little curved radius and it's held in place by that pinch bolt and it is fairly self-explanatory but just double check yours is in the correct position [Music] next up are your adjustment points of the derailleur of which there are four major things on every system for you to adjust the first one we're going to talk about is your cable tension so the inner cable runs from your shifter all the way down and it's clamped on at the bottom here now you adjust this when you're in the smallest sprocket which is your highest gear now note that this is the point where the system has the least amount of tension on it when you pull the cable through here you shouldn't be pulling it tight just taut okay so it shouldn't be baggy at this point here just enough tension in here that when you tighten up the pinch bolt you can pull on it and you can see it moving just a little bit like this so essentially if the cable here is actually baggy there's going to be a big delay when you change gear at the shifter it's probably not going to correlate to you changing the gear at this end and the complete opposite could be said if it's too tight then you're gonna be overshifting we'll already actually be trying to shift up the block there again it should just be taut okay so make sure that that is nice and secure and then you can fine tune by adjusting the barrel adjuster at the lever now that's typically something you do once you're riding along or once you've got the rest set up to make sure the gears are completely indexed now there's the three other adjustment points to make sure you can understand there's the b screw and there's the limit screws the limit screws are responsible for the position of the guide wheels which are on the sprung cage in relation to the cassette so there's one to adjust it over there or under the smaller sprocket and one to adjust it under the bigger sprocket the derailleur needs to line up completely in line with those two sprockets in order for the indexing of the gears to work correctly so in this case it's the shimano derailleur they're adjusted by allen key sometimes it is a screwdriver for this the upper of the two limit screws is responsible for the the smaller sprocket and the lower one is responsible for the larger sprocket and then there is the b screw this is also known as b tension now this is responsible for the height of the pulley wheel cage underneath your bigger sprocket here and the height of this will differ depending on how big your cassette is on the rear so there'll be measurements anything from three to up to about 10 millimeters depending on the model and the brand and of course with the size that you have so you will need to double check that with the manufacture of your one but if there's not enough distance there you'll actually find the upper guide wheel will be rumbling as it contacts the cassette so it's clearly not right and if it's too too much of a gap there's going to be a delay in shifting back down into a higher gear so that's just one of the things that can happen [Music] so we've checked all the hardware over and we know it's in good functioning order and we've checked this all aligned on the bike so the only other thing that can really affect your gears working correctly is the indexing now this refers to one click at your shifter correlating to one gear changed at the derailleur and really is all about cable tension this is why you have the barrel adjuster on the shifter so you can make fine adjustments whilst you're riding to make sure everything's working now what you want to do to start with is make sure you're in the smallest sprockets that's your highest gear now when you're in this there's the least amount of tension on the system so you may need to add tension with the barrel adjuster in order to get the gears to shift so try one click first as you're just pedaling along it should hop up one gear if it's not apply some tension which means counter-clockwise adjustments on that barrel adjuster until it jumps up do this until it jumps out the first two or three sprockets and it goes back down again successfully if it's not going down successfully you need to back off some of that tension and likewise if it jumps up too many in one click the same thing you've got too much tension it's pretty simple once you've made those limit adjustments and you've got the b tension really it's all down to cable tension so go systematically through those gears like i said experiment with the barrel adjuster on the shifter there and if it's still not playing ball then really there's a couple other things that it could be you in the cable inside the outer housing could be completely filthy so if there's friction in there that's going to affect everything in which case it's time for a new inner cable and whilst you're at it flush out that outer housing with some good lubricant and there's one other teeny thing that can happen as well which we haven't referenced is you might have a stiff link on your chain so if you're noticing any clicking whilst you're pedaling cycle your pedals backwards watch what the pulley wheels are doing if there's a stiff link you'll see it would just jump up and down very slightly as it goes past and to get rid of that you can literally manipulate that chain link by hand or with a good multi-tool that has two sets of jaws on the chain guide put your chain in the closest jaw to you and basically you can use this to just free that link up very slightly you've got to do it just a tiny bit of pressure on it all it does is just enable the outer links just to free up any sort of pressure they have on them that causes the stiff link well uh that's really all there is to gears they're quite simple you just have to make sure you've nailed a few things making sure of course your hardware is in really good condition good working order making sure it's installed on the bike correctly and it's aligned everything has to be perfectly lined up in order for those gears to work and then of course your cable tension now absolutely key to making sure those gears jump up and down as you want them to now unless your bike's snapped or anything else that's dramatically going to affect those things this hopefully will answer the question of why my gear skipping or not working hopefully you like this new format let us know what you think in the comments underneath and uh well we'll see in the next video see you later

Channel: GMBN Tech

Views: 276,501

Keywords: ask tech, mtb tech, mtb gears, mountain bike gears, bike gears, drivetrain, gears, gears skipping, gears clicking, fix gears, maintenance, repair, problem, bike maintenance, gmbn tech, bike tech, mountain bike, Bicycle (Product Category), MTB, bicycle, gmbntech, GMBN, Global Mountain Bike Network, mountain biking, Downhill, XC, Cross Country, Enduro, MTB skills, bike skills, mountain bike skills, bike, bike riding, cycling, gmvn, doddy, andrew dodd, ཅ, ᐶ, scbpgmbn15, 1k, 1o, ኽ, 1d, 1w, Ꮖ, ዝ, ꔇ, ፕ5, Ҫ

Id: sZ-ZeX6npA0

Length: 14min 11sec (851 seconds)

Published: Mon Apr 05 2021