Ive just purchased a 2nd hand diamond back bmx. The chain ring seems to be moulded in with the pedal arm.

I bought it to practise wheelies but the trouble is the gearing is way off for me and could do with a smaller chain ring.

Is there anything i can do?

Bigger freewheel?

APF

The fronts 44 and back 16t.

Is there anything much bigger than 16? Are the freewheels pretty universal fit?

Sheldon knows.

https://www.sheldonbrown.com/freewheels.html

Looks like there are 18T about, which will help.

You’d have to confirm the thread pitch et c.

APF

Actually it looks like i can replace the sprocket.

Its a one piece crank. Will any sprocket fit?

Woah, getting into BMX specialism here.
A bit above my pay grade I’m afraid.

APF

Look about for a 42t front ring-

https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p4840.m570.l1313.TR0.TRC0.H0.Xbmx+42.TRS0&_nkw=bmx+42&_sacat=0

You’ll have to bugger about with the chain length if the axle slots aren’t long enough though.

edit- or fit a spider and use bolt-on rings-

https://www.ebay.co.uk/sch/i.html?_odkw=bmx+42&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xbmx+spider.TRS0&_nkw=bmx+spider&_sacat=0

cookci – Member
Ive just purchased a 2nd hand diamond back bmx. The chain ring seems to be moulded in with the pedal arm.

1, 2 or 3 Piece crank? I can’t imagine any self respecting BMX has an in moulded/stamped ring though Diamond Back have become pretty much BSOs in BMX terms these days

Pics?

Does it look like this?

If so THIS will lower it a fraction but it’ll look awful and you’ll have to strip the BB and reinstall which is a loose ball nightmare even if you’ve got the tools (though I used to do it all the time at 14 so it’s not hard)

It’ll almost certainly be equivalent to 44:16 gearing like every BMX in history no matter what no of teeth it has either end – what I’m getting at is do you really need lower gearing? It’s usually pretty much perfect for everything which is why there’s not much variation.

Wheelies? Just pull harder.

And a wheely is sitting down, standing is a catwalk

Its a diamond back viper.

Its a one piece crank by the looks of things so can i not go much lower on the teeth of the sprocket and just shorten the chain?

Something like this?

Look at this on eBay http://www.ebay.co.uk/itm/262744943616

You can do that but what the hell are you trying to do that you want to fit a 28T ring?

So im getting the feeling the standard ratio im on is ok for a catwalk… feels a bit stiff to me but i have never ridden a bmx before!!!

The best bike for learning wheelies on is a mountain bike. Do you have one? They often have variable gear ratios, too.

Hth

Seriously though,BMXs are pretty difficult wheelie (low seat, cramped knees, rubbish brakes, narrow bars). Manuals on the other hand, completely different.

Agree, great for manuals but rubbish for wheelies (unless you get a ridiculously long seat post but even then it still won’t be long enough.

BMX race warm up / down seatpost 🙂

44/16 is standard oldschool BMX gearing – nuskool equivalent is 25/9 or 28/9 (with a mini cassette hub) – if you fit a 28T ring with a 16T freewheel your gearing will be waaaay too low. I’ve run 39/17 before now (but I’m a wimp) – go 42T or even 40 if you want to make things slightly easier and yup, cheap pressed chainwheels are pretty much universal fit and freely available on ebay.

25/9 pedals almost the same as 44/16 right?

Its all about clearance, weight and strengh from what i read?

Yup, most modern day BMXs will be spec’d with a cassette rear hub and 25/9 – better clearance but more chain wear iirc. I run 39/15 on my early 2Ks ride which is a little lower but suits my wimpy legs fine.