Bicycle Mechanics - My new bike ... stuffed? Please look

Hi i am a new user from Australia. I recently, 1 and a half weeks ago, purchased a MONGOOSEPRO Calafornian 2002 model *1st hand* (Race bike bmx) Not sure if they sell them in other countries and i am pretty new to bikes.

A few days ago I jumped from a platform about half a meter and landed pretty hard on concrete. This caused my seat to get really loose and wobble. So i tightened it with an allen key real hard. It was very tight so i take it out for a test, about 10minutes (not jumping the bike for the whole 10 minutes) it becomes loose again. So again i tighten it real hard and once again 10-15 minutes of riding the seat becomes real loose and wobbly. Now that is just one problem from yesterday. Because today i realised when im pedaling it makes this weird noise, like a screetching sound. It's hard to explain but it sounds like its cracking or something. Now i am not sure where the sound is comming from because the front brakes where acting weird too.

Please if anyone can help me, Please tell me how to solve my problems. Thanks

Hard to tell from your limited description. Do you have access to a digital camera that you could take some pics of your bike?

That would help.

1) I think your seat clamp is stripped out, New one only 3 or 4 USD (Don't know the currency exchange)

2) Creaking maybe from loose cranks. Grab a crankarm in each hand and move sideways to see if there is any play in the bottom bracket.

3) Creaking could also be from a loose front hub. This may explain the brake rubbing as well. Grab the top of the wheel and move it sideways. Is there any play in it?

My suggestion. Take it to a bike shop for an estimate (ONLY!) if it costs more than $20.00 (USD again!) Take it back to the store where you bought it! Get the money and go back to the bike shop and put a downpayment on a better quality bike!

Good Luck & L8R

Like a2psyklnut says, you should check the seat-post collar to see if you stripped it.

If the collar and bolt seem OK, then check to see if you concaved the seat post. It is hard to see with the naked eye. The way to check is to pull the seat post out a little or push it in a little to see if the other area of the post is tighter and not prone to looseness. This would indicate that you concaved the post around where the collar was.

As for your other problem, check your front wheel. You might have warped it. Maybe you can get it back with a wheel tuning.

It is normal for a new bicycle to require readjustment after initial break-in. If you have aluminum cranks, make sure they are securely mounted onto the bottom bracket spindle; you will quickly destroy them if they are loose. When one buys a decent-quality bicycle from a reputable bike shop, one or more break-in tuneups are built into the selling price.

As far as the bolt that secures the seat post goes there is a chance that you have stretched the bolt (as you said you tightened it real tight), although that would make the bolt/nut more difficult to tighten when it would normally be free. I could be completely wrong but a similar thing happened to me with one of the bolts that holds the clamp for my handle bars although I had clenched a wrench onto the allen key.

:crash:

ok, i found out when i pedal (not seated) when i get near the bottom of the rotation of cycle about 4oclock stage thats where you hear a EEERRRKK squeek sorta noise. For both left and right cranks. And then stops making noise at about 8oclock stage and starts again to 4-5oclock stage.

Also if there are scratches that take a bit of paint of, how will i patch them back up again. Like i know if u just put normal paint the texture wont be the same and will look different. Is there any things i need to know to respray scratched off paint?

Thanks

Originally posted by Cheatz
ok, i found out when i pedal (not seated) when i get near the bottom of the rotation of cycle about 4oclock stage thats where you hear a EEERRRKK squeek sorta noise. For both left and right cranks. And then stops making noise at about 8oclock stage and starts again to 4-5oclock stage.

Also if there are scratches that take a bit of paint of, how will i patch them back up again. Like i know if u just put normal paint the texture wont be the same and will look different. Is there any things i need to know to respray scratched off paint?

Thanks

It sounds like your cranks are bent.

Paint wise to get a perfect finish you'll need a professional respray - otherwise try thin layers of auto touch up paint or nail polish.

Richard

Check the crank arms to see if there is any play in them, all your jumping may have loosened the nut holding on the crank arms.

Use automotive touch-up paint for painting, you get cheapest at a car parts superstore like Rocca Bros/Marlowes/Super Cheap etc.

I had the same probvlem with my primo rod seat post as cheatz, i tightened it as hard as i could and it still got lose. After a while the teeth on the post ground away and now its smooth. What do i do to stop this?(im already getting a new post)