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Old 08-16-03, 07:41 PM   #1
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Newbie Building a BMX from scratch - HELP! :)

Hello all,

Thanks for the wonderful forum, just stumbled upon it today. I am getting into BMX bikes again, as they're building a skatepark in our town, and am working on an old school project, with slight utilization of some of the newer bmx technology that is available today.

I've recently stripped an old *very light* Diamondback frame, and repainted it. The only thing I'm keeping from the orginal bike is the frame, and the fork, which leaves me with a lot to purchase. I bought a set of cw style handlebars, looking for an old plastic seat, and have some mag wheels on order. I'm sticking with the above, as far as looks go, and have some questions regarding some of the other componants.

First, is there ANY advantage between 1pc, 2pc, and 3pc cranks? Is it simply a mere convienence factor, or will a high quality 1pc crank do the trick? I've never been able to get a solid answer from any of the local riders here, they just suggest the 3pc, but have no idea why it's good.

Is there any advantage over a chainwheel verse a chainring, or is it a matter of preference/looks? If so, what is the advantage of the superior? Are most chainwheels/rings compatible with most cranks?

As far as speed goes, outside of the gear ratio, what component makes the biggest difference, the freewheel, or the crank setup? In otherwords, where should I spend the money if I'm on a budget?

And lastly, are there any compatibility problems I should watch out for, or are most parts interchangeable? I noticed the seat post on the Diamondback was a lot slimmer than the seatpost on my brother's bike which is modern; I'm wondering if I'll run into a lot of these problems, and if so, what are the obvious things to look out for?

Any and all help on any of these areas would be GREATLY appreciated. I want to get this old beast back on the road and in mint condition as soon as possible; got a lot of practicin' to do before the free park is built.

Many Thanks!

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Old 08-16-03, 08:07 PM   #2
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3pc only, i would buy profile cranks, chainrings i believe are 2 piece, stick with a one piece, they are much better, seatpost diameter is one of the few things that doesnt stay standard on bikes it is always different. Does it have a standard threaded headset or a aheadset? IF you will be on ramps you want to gear pretty low, like 43 front and 15 rear or maybe even lower, it deonds on you.
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Old 08-16-03, 11:14 PM   #3
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Some frames take different size seat post so make sure you buy the right size
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Old 08-19-03, 09:02 AM   #4
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1pc cranks are cheaper, 3pc are much stroner and usually lighter. Don't bother with 2pc, they're basically the bad bits of 1pc and 3pc combined.

Pretty much all BMXs use chainwheels. Chances are you'll need an adaptor if you want to use a chainring, which is just more weight. Plus chainwheels are much stronger.

A decent freewheel is key to rolling smooth, but setting your cranks up right is important too. You want them as loose as possible without the bearings wobbling or anything. Make sure your freewheel is on the hub good and tight and that you keep it clean and greased (as with everything else).

Most modern BMXs have 1inch seatosts (some have 26.4mm), whereas most old ones use 7/8ths. You might not be able to find a microadjust post that'll fit, but I guess you won't mind since you're willing to put up with all the other problems old school bikes entail

Have fun!
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Old 08-19-03, 09:16 AM   #5
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As far as cranks, I too would recommend a set of Profile 3 pc, they've become the Benchmark of the industry for a good reason. They're strong, easy to install, look good and last forever.

There are a lot of copies, and Profile has made their cranks and put other companies stamp on them. i.e. GT at one time had Profile make their cranks.

As far as chainring, vs chainwheel. A chainwheel is stronger. However, a chainring is easier to change out since you don't have to remove the crank. Also, a chainring sometimes will solve a "Chain LINE" issue.

As far as 1 pc cranks. They are usually forged and not as strong, albeit much cheaper. You can get a set for under $20.

Most 1 pc cranks use 1/2" pedals, most 3 pc use a 9/16" pedal, so remember that when buying your pedals.

The fork and headset may be another issue. Back in the day, most everyone had a 1" steerer tube, now, a lot of people are going to a 1-1/8" steerer. This may cause problems when buying a headset and stem. Most newer bikes are going with a "Threadless" stem, versus the type that had a threaded steerer tube and a big Nut on the top of the headset. Make sure you get the right one for your forks.

"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, "WOW, What a Ride!" - unknown
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Old 09-14-03, 06:58 PM   #6
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if u want mags buy spin they price but worth it
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Old 09-29-03, 09:34 AM   #7
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ok here are some tips, get a 3-peice profile crank dont get a 2-peice a 3-peice is the best choice because they are seald berrings witch keeps dirt and water from rusting the inside body of the crank. If you are looking for some good bike parts go to what type of riding are you going to be doing? that effects everything you need for your bike if you want some more tips go to my message boards its not much yet but I have some people that are signing up on it.

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