a clunking sound from bike crank?

[raggie33]

i am mad i mean it took me a long time to save to get this bike 250 is a lot to me and i get crap i cant afford to get it fixed unless its something i can do my self i cant belive they dont check this stuff before they send em out

 

[mechBgon]

I can't afford to get it fixed unless it's something i can do myself

If your bike has the problem I suspect, then unfortunately the specialty tools required to fix it yourself will almost certainly cost you more than just having the bike shop do it, even if all you need to buy is the crank extractor and a cartridge-BB tool (one of the simplest cases).

I can't believe they don't check this stuff before they send 'em out

At a decent bike shop, that stuff does get checked before we send 'em out. But we're not a mass-merchant box store... it matters to us that you're happy and safe, not just that we got clean away with $250 of your money before sending you off on a bike with brakes that don't work, etc.

 

[es2qy]

I echo the others, a bike shop is your best bet. For your wheels, they true in much the same way as regular spokes - right spoke pulls rim to right, left pulls to left, both pulls concentrically, be sure to use a good nipple wrench as paired spokes take high tension. Sorry to hear of your troubles.

 

[raggie33]

is it goinjg to get worst i can live with the noise long as it dont break like i said i dont own a car so this is my only transportation

 

[nisshin]

Here are links to famous DIY bicycle repair/maintenance websites:
Sheldon Brown
Park Tools Repair

 

[wmirag]

Without seeing your bike (the Amazon picture didn't have enough resolution) , I can't tell if your problem is the same one I had many years ago.

If and only if one or both cranks is secured to the crakshaft with a wedged bolt, read on.
If not, don't bother, I can't help you.

I had a problem where the bolt that secured the pedal was not originally tightened down enough. With repeated hard presssure, the wedge action loosened and I had a clunk upon every downstroke.

I put the threaded end of the bolt into a 1 foot long 3/4" I.D. pipe and pounded the crap out of the bolt head. That seated the wedged bolt firmly against the flat of the crankshaft. Then I tightened the nut at the other end of the bolt. I never heard another peep out of it.

Hope that helps.

W.

 

[mechBgon]

Is it going to get worse? I can live with the noise as long as it doesn't break. Like i said, I don't own a car, so this is my only transportation.

If it's the problem I think it is, then it can potentially get worse, yeah. The crank-bearing unit could continue loosening, with various ramifications. When you get a chance, put up some close-up photos so I can see what type it is.

By the way, most bike shops would charge between $10 and $20 to get this handled, and you can ask them to assess it and give you a price estimate before you have to commit to having it done.

 

[orbital]

If it's the problem I think it is, then it can potentially get worse, yeah. The crank-bearing unit could continue loosening, with various ramifications. When you get a chance, put up some close-up photos so I can see what type it is.

By the way, most bike shops would charge between $10 and $20 to get this handled, and you can ask them to assess it and give you a price estimate before you have to commit to having it done.

+1

When I said take your bike into a shop and get a bottom bracket overhaul (or bottom bracket reinstall may be better wording),
I didn't mean to scare you away.

What they need to do is put your bike on the stand, pull off your cranks and bottom bracket.
Then, its putting it all back together with the right wrenches and torque, bit 'o lube....:huh:
Just be real nice and they'll work with you.

Ask them to snug up your pedals if you haven't already,...they both tighten toward your front wheel....nothing crazy here.

~ If you say its impossible to take your bike in, either you burned your bridges at every bike shop in your area,....or,.....

 

[raggie33]

ty everyone lots of options to consider

 

[greenpea76]

On my Shimano bottom bracket cartridges, the splined shaft or the tapered square shaft the cranks slips on to, required lube. This is assuming that its a threee piece crank and in the amazon link, it looks like it is. I didn't read through all the posted suggestions, but I am a fairly experienced bicycle mechanic and have dealt with many similar sypmtoms of a popping type clunk sound. Use a thick viscous grease if you can find some at a bike shop or even a hardware store. Target folks that do assembly don't usually know what they're doing when it comes to assembling and lubing components"properly".

I don't know how mechanically inclined your skills are, but most 3 piece cranks require some sort of puller to pull the crank itself away from the bottom bracket. Some can be rocked back and forth a few times and they will come loose. Then coat the bottom bracket shaft liberally with grease and reinstall the crank and torque to proper spec.

There are many vids on youtube that can give you an idea on how to do this. I did a search for "bottom bracket crank removal".

Hope this helps.

 

[PhotonWrangler]

Raggie, I've had the same clunking behavior on my cheap-o bike. It's annoying but I didn't try to fix it because I'm a complete putz with mechanical stuff and I figured I'd only make it worse if I messed with it. Now I know what the problem is. Thanks for starting this thread!

 

[jtr1962]

If it's a cheap Schwinn from Target then it likely has an Ashtabula crank, not the 3-piece type. Bad news is these are much more likely to make all sorts of clunking sounds and otherwise come out of adjustment. Good news is you don't need crank pullers or any special tools to work on them, just a large, adjustable wrench. That being said, if it were my bike I'd buy an adaptor (scroll to middle of page) to convert to the much more reliable 3-piece crank. In fact, I did exactly that on my second bike (an old Huffy).

 

[PhotonWrangler]

Thanks, JTR. It looks like that Ashtabula crank, so that must be the culprit.

 

[orbital]

+

This is the bike, those are not one-piece cranks.

 

[raggie33]

im not 100 percent sure if the noise is coming from crank but id say 95% or higher its mostly under big loads like when im going up hill.like i said i live on a bottom of a huge hill .the noise realy makes me crazy

 

[Coop]

This class of bike usually comes with the cheapest of cheap cartridge bottom brackets. The nois usuall comes from damages bearings. Not much to adjust here. The decent quality Shimano square taper Bottom Brackets will usually cost about $15-$20. Having it installed at a bike shop will probably be cheaper than buying the tools to do it yourself (you'll need a crank excractor, BB tool that fits current BB, BB tool that fits new BB too if you're unlucky and a torque wrench. Torque wrench is vital, without it you will most likely over tighten it which is probably the no. 1 cause of BB problems).

If you take a little care of your bike, the new BB will last you 10 years easily.

 

[raggie33]

maybe ill try that i love the bike other then the noise bad thing is it only does it when im going up hill or pedaling very hard.and a course at that point im so tired with pedaling it just gets me madder lol.it has altus in the rear which ive heard aint the rest

 

[Coop]

I saw somewhere online that the bike you posted the pic of comes with a Shimano BB, this is most likely the low end Shimano UN-26.

I recommend investing a few dollars in getting this one: http://www.jensonusa.com/store/product/BB309F06-Shimano+Un54+Bottom+Bracket.aspx

This model has proven itself over the years and will last you a looooong time when properly installed and taken care of.

Keep in mind that bottom brackets come in a lot of different sizes. You have to look at:

Cup thread (Most likely 'English' for your bike)
Shell width (68mm & 73mm are most common, you can easily measure this by holding a ruler along the crank housing on your bike, measure between the cups)

Spindle length (what you need depends on Shell width and the number of chainwheels on your crank. If you get this wrong, your chainline will be off and shifting will become a pain)


As there are a lot of factors to take into account, it's best to have it checked at the bikeshop.