[Kntr]

Who makes the shortest cranks? I need a set for my kids bike. She is currently running 165mm and they hit the ground when she turns and pedals. Any ideas?

 

[jvnixon]

I think you can get track cranks down to 150mm or so.

 

[HAB]

What sort of BB? And what chainring setup?


Sugino makes a 152 square taper, 110mm 5 arm triple.

 

[freeridefool]

I see 3piece cranks on kids bikes in 120 all the time. Im not sure of the companies but I know they exist.

 

[Kntr]

She is currenty running:
CRANKSET--Truvativ Blaze w/ Truvativ Box guide
CHAINRINGS--34T, 4 bolt, compact 104mm pattern
BOTTOM BRACKET--Truvativ Power Spline, sealed cartridge bearing

 

[HAB]

OK, so those Suginos would work. You'd need a different ring and BB, but could get the same gearing and all that.

 

[Kanye West]

Check Profile. I believe they make them down to 150mm or 155mm.

 

[Brian HCM#1]

I have some cheapo FMF's 155mm on my kids.

 

[ianjenn]

Check Profile. I believe they make them down to 150mm or 155mm.

Profiles go down to 145!

http://profileracing.com/profileracing/estore2/index.php?catid=1

 

[Sonic Reducer]

got a drill press? you could redrill some older cranks to whatever length you wanted. that would be light, cheap, and you get the best length you want. even old square taper cranks would be strong enough with light weight rider and the shorter leverage on the parts. plus its a kids bike, not like it needs to have nice ass parts.

 

[Nagaredama]

Sinz BMX ISIS cranks get as short as 135.

http://www.danscomp.com/452036.php?cat=PARTS

 

[Kntr]

The cranks on her bike are 165mm and she has 5" of travel with a 12" bottom bracket.

They are waaay to long now. They hit the ground when she pedals and turns on FLAT ground.

Any ideas how short I should go? I was thinking 140mm.

 

[syadasti]

shortest cranks are probably off mini bikes:

 

[HAB]

Christ, what 5" bike is that low?


Yeah, I think you're about on track with the 140s. That's about what it would take to give her normal ground clearance on that bike.

How tall is she?

 

[Kntr]

She is 60 lbs and 4'2". Here is a pic of the actual bike. See how close to the ground the pedal is.
Anyone ever hear of SINZ cranks?

Isis?
http://www.sinz-racing.com/productpages/sec-10.html

Square taper?
http://www.sinz-racing.com/productpages/sec-19.html

 

[freeridefool]

Sinz is huge in the bmx world. They make some pretty high end stuff for kids minis and what not. If she isnt that heavy they would be fine.

 

[CBJ]

They look good too and would be great on that killer ride.

 

[Kntr]

So Im going to get the cranks soon. Any idea what size I should get? Will the 135mm be too short? Any ideas?

Bike BB height is 12" and has 5" of travel.
Rider is 4'2" and 60 lbs... for now. I can alway keep the 165 mm for later.

 

[manhattanprjkt83]

shortest cranks are probably off mini bikes:

always a great help

 

[Kntr]

So Im going to get the cranks soon. Any idea what size I should get? Will the 135mm be too short? Any ideas?

Bike BB height is 12" and has 5" of travel.
Rider is 4'2" and 60 lbs... for now. I can alway keep the 165 mm for later.

Anyone have an idea? I have no idea what length to get.

 

[verticult]

I have built a few kids bikes and I usually cut, drill and tap a set of long cranks. I think they usually come out to 150 or so.

 

[jcaramia]

I have built a few kids bikes and I usually cut, drill and tap a set of long cranks. I think they usually come out to 150 or so.

That frame looks awesome! Actually, that whole bike looks awesome.

 

[Patan-DH]

hey kanter 145mm is going to work, that is 20mm shorter wich will solve clearance issues

 

[spocomptonrider]

She is 60 lbs and 4'2". Here is a pic of the actual bike. See how close to the ground the pedal is.
Anyone ever hear of SINZ cranks?

Isis?
http://www.sinz-racing.com/productpages/sec-10.html

Square taper?
http://www.sinz-racing.com/productpages/sec-19.html

That has to be one of the best looking kids bikes I've ever seen, I would've been so stoked to have something like that when I was a kid.

I have seen a few sets of custom cranks on kids bikes, as someone has already said I think they just drill/ cut down normal cranks to get the right length, obviously not as strong as stock but should be fine for a kid.

 

[weedkilla]

My 9yr old lad gets away with 165mm cranks on his older big hit, its low but he manages. If I had found a 150 or 155 crank I would have gone with it, however now (after 6 months) there is no point changing. Out of interest his bb height is 12.5" so a 10mm shorter crank should make it manageable for her.
I doubt you will go wrong with a 150mm crank.

 

[Kntr]

Thanks for all the help. Im upgrading a few parts to lighten the bike too. I bought a used Thomson seatpost so far. The stock seatpost is a boat anchor. Im hoping to get the bike under 30 lbs. We went for a ride last night and the long cranks didnt bother her too bad. I might just try smaller pedals first. The Specialized pedals on the bike are super thick and huge. Wellgo makes a road platform that is light and super small. hmmm