# Pedals pop when pedaling hard; chain sometimes skips



## vassock (Jun 29, 2009)

I have two issues with my mountain bike.

1. The pedals always make a popping noise at the same spot when I am pedaling hard, such as up a hill.

2. The chain occasionally (not often) skips.

I already used a chain stretch meter and it does not appear that the chain is stretched (neither 1.00 nor 0.75 fits).

I tried pedaling backwards slowly and have not seen the chain get stuck in the bent position.

I did some reading and people are suggesting the bottom bracket (where the pedals go into the frame) needs to be disassembled, lubricated, and reassembled. Unfortunately, I lack the tools for this. I don't have a hex key big enough and certainly don't have a cycle crank puller. Will these tools do the job?

Allen Wrench Hex Key 30pc Set Metric SAE Standard Short Long Arm CRV Steel | eBay

New Cycling Bicycle Bike Mountain Crank Wheel Puller Remover Removal Repair Tool | eBay


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## rangeriderdave (Aug 29, 2008)

I don't think it is the bottom bracket .it would do it all the time. The popping could be a just a tiny adjustment in the cable tension . You could have a bent derailleur hanger ,look at it from the rear ,it should be vertical and align with the cassette.


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## vassock (Jun 29, 2009)

rangeriderdave said:


> I don't think it is the bottom bracket .it would do it all the time. The popping could be a just a tiny adjustment in the cable tension . You could have a bent derailleur hanger ,look at it from the rear ,it should be vertical and align with the cassette.


This bike is single speed: it has no derailleur or gear cassette.


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## milliesand (Jun 29, 2015)

On your list, the hex set would be OK for home use on the bike. I prefer ball end type, myself. You might consider, also, a foldable set to bring on your rides. My handlebars have shifted sideways during some crashes (and you WILL crash) Easy to fix out yonder if you have the tool, and PITA to walk back without.

For the crank puller, Make sure it fits YOUR crank.

You're also going to need a tool that fits into the bottom bracket. That will expose the area you need to clean and regrease.

FWIW, these tools are pretty cheap - about what you would pay the LBS to do the job once. While I'm all for supporting the local LBS, some things you should be adept at :Bottom brackets, brakes, cockpit fit, flats.. Good luck


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## mack_turtle (Jan 6, 2009)

popping: so many possibilities here
1. are your pedals tight in the crank arms? I don't mean to insult your intelligence, but I have seen this one several times. remove, grease the threads, and reinstall.
2. what pedals do you have and how are the pedal bearings? sometimes pedals that are worn out or are just junk to begin with do this.
3. chainring bolts- do you have all of them and are they right.
4. crank arm/ BB interface. if you have a splined or square taper BB, those things have to be torqued down properly, usually 29-35 ft/lbs, depending on the design. if they have been ridden loose, the arm is probably warped and needs to be replaced. those bolts are almost always 8 mm, so you need a metric set. 8mm comes on most metric hex sets.
5. BB cups- those cup threads should be treated with a medium thread locker, grease, or anti-seize. if the BB came with the bike, there is a good chance it was never installed correctly and is dry and creaking in the frame.

slipping- what kind of chainring and cog are on the bike? if they were not designed for single ring/cog use, they are going to suck like that.

for instructions on bottom bracket issues, look for help on parktool.com


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## watts888 (Oct 2, 2012)

single speed is the devil.


Is the rear QR loosening up enough to add just enough slack you're getting some chain slap induced skipping?

shark finning of crankset teeth?

cheap rear hub, and every time you're "skipping the chain", you're actually skipping a pawl inside the freehub?


and get the tools. If you only use them once, still worth it. My bet is once you have them, you'll do maintenance a bit more often.


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## mack_turtle (Jan 6, 2009)

watts888 said:


> cheap rear hub, and every time you're "skipping the chain", you're actually skipping a pawl inside the freehub?


that will be an important distinction to make. is the chain jumping over a tooth on the ring/ cog, or is the drive mechanism in the hub failing?


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## vassock (Jun 29, 2009)

mack_turtle said:


> that will be an important distinction to make. is the chain jumping over a tooth on the ring/ cog, or is the drive mechanism in the hub failing?


I don't know if the crank puller will fit MY crank. Any suggestions?

I will place the order for the hex keys now since you guys seem to approve.

Regarding testing some of the items you mentioned, I don't even know what some of those words mean. Sorry, I have very limited knowledge of bikes. My maintenance experience includes repairing and installing bike tubes, replacing bike pedals (the ones I have installed are cheap stock pedals I got off of a ~7 year old bike after my current stock pedals snapped in half), and replacing my mechanical disc brakes with hydraulic disc brakes: all simple stuff.

Any troubleshooting you can recommend? Any photographs I can take of the bike to help?

Bike is Gravity G29.


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## mack_turtle (Jan 6, 2009)

if you don't know a term, take ten seconds to Google it and read it again. all this information is useless to you if you don't take the time to try to understand bike terms.

that tool you posted looks like the right one for Powerspline and square taper cranks, which you seem to have. I know Bikesdirect is notorious for changing parts without warning, so I am not 100% certain about that. if your crank arm says "powerspline" on it or has a square-shaped axle on it, you can use any puller designed for a square-taper crank arm. be sure to look up instructions on how to use that tool because you can strip out the threads on the tool end of the crank arm if you do it wrong. Park Tool's help site is your best friend here.

when you reinstall that bolt on the arm, you have to do it up pretty darn tight. I always use a torque wrench so I can get the torque just right according to the manufacturer's specs.

when you get the arms off, you will need to remove the bottom bracket, clean it up, treat the threads with very durable grease or medium thread locker and reinstall. you will need a "bottom bracket spline tool" of some sort. note if the threads are dry or if they were treated upon installation. once again, read Park Tool's instructions are very helpful. the tool looks something like this:










regarding the slipping- it could be the chain popping over a worn tooth on the chain for some reason, or it could be the ratcheting mechanism in your hub that is failing. you know that rapid-fire clicking noise your hub makes when you are coasting forward? if you drive the wheel forward and the ratchet does not catch but slips instead, that will have the same effect as "slipping" or "skipping."


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## vassock (Jun 29, 2009)

So it can be anything from the hub at the rear wheel to the bottom bracket at the pedals.

What kind of grease do I need for these parts and which do you recommend I try to disassemble first? Any way to troubleshoot without first disassembling?


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## mack_turtle (Jan 6, 2009)

grease is grease on applications like this. use thick bearing grease, whatever kind smells nice from Walmart, a auto store or a bike shop.

you described two issues, so we are diagnosing two problems: a popping noise/sensation and a skipping drivetrain. the two seem to be unrelated.

popping noise:
1. do the pedals spin smoothly or do they feel crunchy? if they feel smooth: remove pedals, grease threads, re-install ride. if the sound persists, move on to...
2. remove crank arms.
3. while you're at it, remove the bottom bracket. chances are, it's dry in there and starting to corrode against the aluminum because the factory didn't bother to treat the threads with anything to prevent corrosion and shifty noises. clean it up, grease it up and crank it back down. torque should be around 30 ft-lbs which is pretty darn tight.
4. if you have Power Spline cranks, grease the splines and torque the bolts back down with an 8 mm allen. the torque on those (35 ft-lbs?) is higher than a square taper bolt (more like 29) but it's pretty friggin tight. ride. button everything up and ride.

as for the popping rear wheel, there might not be much you can do if the free hub (the splined part on the rear hub that the cog is attached to) is starting to go. you might learn how to overhaul your hub, pull the freehub and flush it out and reinstall. if not, you're going to want to start shopping for a new rear wheel. when that thing goes, you might end up stranded with a scooter instead of a bike because the wheel will not drive your forward anymore.

cheap hubs don't last long under load. if you're riding a SS mountain bike hard, a cheap hub will not survive very long.


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## watts888 (Oct 2, 2012)

vassock said:


> So it can be anything from the hub at the rear wheel to the bottom bracket at the pedals.


Oh, it could be more. Loose seat post, loose seat clamp, brake rotors not tight, loose rear axle bolt, headset loose, stem clamp loose. Lots and lots of things. Basically, check all the bolts.

If your seat clamp (under the seat) is tight, and the seatpost height adjust clamp are tight, my next guess on popping would be cheap pedals, crankarms loose (simply try tightening the bolts) or bottom bracket is loose (kind of notorious on online bikes, have to remove the crankarms to get to it)

Word of Warning! On the crankarm tool, normally there is a little cap that's removable. You want to remove that cap, or when you start threading it down to remove the crank arms, you'll bottom out against the crankarms instead of the bolt, and that's when you strip out the crankarm threads. If you strip out the threads, nothing you can do other than throw the arms away (after hammering them off and probably damaging the bottom bracket in the process). Watch youtube video's about removing them. Don't try it until you feel comfortable doing it. It's easy to do, but easy to mess up too.


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## vassock (Jun 29, 2009)

watts888 said:


> Oh, it could be more. Loose seat post, loose seat clamp, brake rotors not tight, loose rear axle bolt, headset loose, stem clamp loose. Lots and lots of things. Basically, check all the bolts.
> 
> If your seat clamp (under the seat) is tight, and the seatpost height adjust clamp are tight, my next guess on popping would be cheap pedals, crankarms loose (simply try tightening the bolts) or bottom bracket is loose (kind of notorious on online bikes, have to remove the crankarms to get to it)
> 
> Word of Warning! On the crankarm tool, normally there is a little cap that's removable. You want to remove that cap, or when you start threading it down to remove the crank arms, you'll bottom out against the crankarms instead of the bolt, and that's when you strip out the crankarm threads. If you strip out the threads, nothing you can do other than throw the arms away (after hammering them off and probably damaging the bottom bracket in the process). Watch youtube video's about removing them. Don't try it until you feel comfortable doing it. It's easy to do, but easy to mess up too.


Since the problem might be the chain, I thought I'd get this to reduce troubleshooting time (not worth it for a <$10 product).

KMC Z410 Bicycle Chain 1 Speed 1 2 x 1 8 inch 112L Brown | eBay

Will it fit?

The only difference I see is that the chain above is marked 5H-2. My chain is 4F-2.


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