anyone know how to add shorter cranks to a 2007 walmart sting ray?

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heartlandcruisers

heartlandcruisers

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well I broke my rule and purchased on of those abominations of the sting ray only because it was decently priced and I kind of liked how it looked.
well after getting it home I was going to use the front end on my klunker, but then my wife rode it and decided she likes it .
so it will be spared and fixed up so we can all go riding together ( me my wife and my girls).
but, I have come into a issue that I am not sure how to fix without hacking and welding.
the crank arms are too long for her they are about 3 inches too long and she cannot pedal it.
otherwise the bikes a perfect it for her.
so with that being said, does anyone know if I can swap the cranks out with shorter ones? and if so where would be a good place to buy them?
also can I run a single piece crank arm because I have a star sprocket with modified crank arms already on it and if they would work I will just put that crank set on it.
thanks'
Sean
 
If you got the bike i think ya got, you can easily run any JIS-sized (most common size) square-taper cranks; the BMX world has plenty to choose from, usually with 110mm BCD spiders. I'm afraid you won't be able to run an OPC without major fabrication.... you might be able to run the star sprocket if you could fab-up a spindle to run 3-piece bmx cranks, but that'd be a lot of work for a project like this....
 
Thats the problem with 3 piece cranks. Pain to try and modify in any way. Why people like them is beyond me. If that bike had a one piece I could pick a short one out of my junk and swap it in minutes.

Sent from my GT-P5113 using Tapatalk
 
Second problem is gonna be the sprocket, it's attached to the arm so you're going to have to find either a complete set, chain ring and arms, or find a smaller version of the chopper sprocket. They did make a 16" wheeled version I believe, and that sprocket has got to be shorter...

Carl.
 
is that for gear ratio or estetics ? you could swap the rear cog for a larger one instead of changing the whole crank
 
The 3" cranks on bicycledesigner.com are all one piecers.... they will not fit the OP's bike.

Not to be pessimistically pragmatic, but it sounds like this bike fits your wife very poorly, if you're really going to need 3" cranks for it.
 
I don't remember how long the stock ones are (threw mine away), but I think they are 175mm (length should be stamped on the back of the arms).
In any event, here's a 165mm set:
http://pages.ebay.com/link/?nav=item.view&alt=web&id=360920359131&globalID=EBAY-US

160mm(it's white though....paint/wire wheel can fix that)
http://pages.ebay.com/link/?nav=item.view&alt=web&id=301713201680&globalID=EBAY-US

You might a crank puller tool, here's a good price on a Park unit.
http://pages.ebay.com/link/?nav=item.view&alt=web&id=391213297020&globalID=EBAY-US

Hope this helps.
Cheers,
Dr. T


Sent from my iPad using Tapatalk
 
Well, it seems like folks have missed some details here. The guy in the OP has one of these bikes:
Stingray_red_HiREs.jpg

These bikes come with 3 piece cranks with 170mm-long crankarms. Apparently, the OP needs crankarms that are significantly shorter than the 170mm in order for his wife to fit the bike. 170mm mnus 3"= 95mm long crankarms, which is a tough bill to order.

The thing about these bikes is, they have English-threaded BBs, regular 1.37"x24tpi theads, but the shell itself is extra-wide to accommodate the very fat rear tire. The OCC/Stingray Chopper BB shell is 120mm wide, whereas standard English-thread BB shells are 68mm wide. So, the OP cannot change the BB, at all, without frame mods. He cant's run an OPC or the Sportsman Flyer crank, as these need American-spec BB shells. He can't run a 2-piece or other external-bearing set-up or a BMX tubular crank, as the spindles aren't wide enough, unless he can fab-up a spindle that's almost twice as long to fit the 120mm-wide shell. In terms of bolt-on solutions, he can ONLY run crankarms designed to work on the JIS-spec square taper spindle that came originally on the bike. Even with doing that he may run into some chainline issues, as different cranks will hand differently on the spindle, but that's about it.

I posted a link above to a bunch of bmx mini race cranks with square-taper interfaces and lengths down to 135mm. The smallest thing i found was this redline crank, at 130mm https://www.danscomp.com/products-PARTS/452040/Redline_Microline_Crank_Arms.html
95mm is reallllly short, and the OP will probably have to either go custom, or see if his wife can make due with a crnk that's only 1.5" shorter than stock.
 
This is a question more than a solution, could the crank arms be cut, drilled and threaded or have a section cut out in the middle and welded back together (to retain the current threaded holes for pedal attachment)?
 
yeah it is sounding like this is going to be more of a project then I anticipated.
I might just have them shortened and keep the originals that sounds like the best bet.
ugh I really hate these things not sure what possessed me to buy it :headbang:
 

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