New school BB 1pc to 3pc tech question - 2011 Haro jr race bmx - cranks too long

[downlowmatt]

Hello!

I'm looking for shorter cranks and a lower gear for my daughter's 2011 Haro jr BMX (she's 6)

I bought it for Christmas, did a mild resto on it (after parcelforce lost it and smashed it up), anyway she loves the bike BUT being only 6 finds the cranks too long (155mm) and gearing too high. When she rides it her knees come up to her chest!

So,

There seem to be three options:

1. Keep the existing cranks, get some crank adaptors to make them shorter, and a bigger chainring (£50ish, will make the cranks wider which I'm not keen on) http://www.bikecare.co.uk/crank_shortners.html

2. Find some shorter 3 pc arms with a bigger chainring (not easy to find, guessing £50+)

3. Swap the BB and put in a 1 pc crank. Small 1pc cranks are cheap (£15ish) and common so this would seem to be a good option - but can you get a BB?

Here's some photos I've found online of the bike and a crank





Cheers

[oldscool]

I could be wrong but if those are the cranks that came out with the bottom bracket reducer, it should take a standard cheap one piece bottom bracket and cranks. You will need pedals also as they will probably be 9/16.

[downlowmatt]

I could be wrong but if those are the cranks that came out with the bottom bracket reducer, it should take a standard cheap one piece bottom bracket and cranks. You will need pedals also as they will probably be 9/16.

Thanks.... I think it has a USA BB at the moment (smaller than the old school BB that I'm familiar with!)... but looking at that picture above there is an adaptor that takes a USA to old school bb

I guess I don't know what BB you can get to convert a new school frame to a 1pc crank

[Gary72]

Get some pics up of the BB on the bike so we can tell what it has currently. The pics look like a race bike and I suspect it will have a euro BB.

[downlowmatt]

Get some pics up of the BB on the bike so we can tell what it has currently. The pics look like a race bike and I suspect it will have a euro BB.

Thanks Gary... I messaged Alans and they said it's a Euro BB. Yes, it's a race bike. You were on the right track, thank you!

In the meantime I've found theses, which although won't change the gearing, are shorter cranks.... and only £2!


http://www.ebay.co.uk/itm/391194077334

In conjunction with a bigger freewheel I could be onto something.
Thanks again for your help

[Jon The Bassist]

The description looks wrong - the crank length seems iffy, I'd double-check before you buy. Also the chainwheel looks fixed so you'd have to throw it if it wore out. I got my lad a decent 'Lasco' 3 piece square taper crank for only a few quid. Good on you for addressing the high gear and long cranks BTW, a lot of completes have been sold like that - I wonder if it's a US preference?

[Gary72]

If it already has a square taper axle and sealed bearings, You should be able to leave that as is and just replace the arms. Keep the longer arms for when she grows. If you get something like the Sinz cranks as shown above the chainring can easily be changed aswell. Might be worth having a mooch(someone used this word on here awhile ago and I seem to have adopted it) over on BMXTALK as it is more race based and people are always upgrading and selling kids stuff.