KIDS CRANKS
One of the biggest issues still today with kids mountain bikes is proper crank length. Aligned hips and a comfortable riding positioning have been put aside by the bigger brands until late. The kids specific brands have changed the game and are forcing everyone else to fall in line but there are many bikes that still suffer from too long of cranks. We like 130mm and under for 20 inch bikes, 145mm and under for 24 inch bikes, 155mm and under for 26 inch bikes and 165mm and under for 27.5 inch bikes. These are just general guidlines though and we always opt for shorter than longer. For instance, we run 130mmm cranks on a converted 26 inch Santa Cruz Bronson for our nine year old!
Goldix Cranks
No excuses anymore! These cheap 3 piece cranks should be on all kids mountain bikes that come stock with too long of cranks. 110, 127, 140, 150, 155, 160 and 165mm alloy arms. You can purchase with or without bottom bracket or chainring. We bought the 150mm set with BB and can attests, they are legit. They weigh in at 528 grams arms and spindle! 24mm diameter axle suitable for frame bottom bracket widths 68mm-73mm. 3 bolt chainring (SRAM style). We purchased with optional BB and it worked well with some spacer manipulation. Those that tried other bottom brackets have reported spacing issues so make sure to grab the BB. Go the Prevelo, Spawn or Trailcraft route if you want better quality control. These are better suited for enthusiast Moms and Dads who are comfortable tinkering with BB spacing or those wanting the value and willing to learn a thing or two.
MSRP: $44 (BB and chainring extra) | Where to buy: Ali Express
Prevelo Heir Cranks
Compatible with 3 bolt direct mount chainrings, these 120 (Q factor 151mm) , 140 and 152mm (Q factor 170mm) cranks are available with 28 and 30T front chainrings. Weight is between 523-561 grams. Fits both 148 boost rear bike and 135mm/142mm rear spacing (make sure to choose 3 mm offset chainring for boost spaced rear ends). Grab a chainring for $39 and a BB for $19. Amazing upgrade!
MSRP: $99 (BB and chainring extra) | Where to buy: Prevelo
Prevelo Heir Carbon Cranks
Compatible with 3 bolt direct mount chainrings, these 145 mm carbon (170mm Q factor) cranks are available with 28 and 30T front chainrings. Weight is 410 g/pair with 30mm diameter spindle. Be sure to pick up 30mm BB for $29. Chainrings available in both 3 and 6mm offsets. These are awesome. The extra 150 grams or so will make a difference in rotational weight for kiddo. If you have a pedaling kiddo, let's say a NICA or Enduro racer, or log a lot of xc miles as a family, these are a fantastic option. They will hold their value as they are niche. With only one length, we would be pumped to see something in the 130 and 150 mm range as well.
MSRP: $300 (BB and chainring extra) | Where to buy: Prevelo
Trailcraft Cranks
Awesome light weight crankset that fits a 68/73mm BB Shell with a 49mm chainline with a Q factor of 168mm. An alloy spindle makes these really light. Crank arms only also available for $169. Weights and lengths (including chainring):
140mm with 26t - 546g, 140mm with 28t - 549g, 140mm with 30t - 558g
152mm with 26t - 570g, 152mm with 28t - 573g, 152mm with 30t - 582g
165mm with 26t - 596g, 165mm with 28t - 608g, 165mm with 30t - 611g
MSRP: $199 (BB not included) | Where to buy: Trailcraft
Brood Bike Co. Styx Cranks
More Great Crank/BB set for the juniors. Available in 130, 145, and 160mm lengths, these cranks will fit sram style chainrings from 26T-36T and provide a chainline of 49mm. Fit standard 68/73mm BB widths. Cranks come complete with bottom bracket, spacers and fixing bolt.
MSRP: $150 | Where to buy: Spawn
XEON mini A1 Crankset
Great 30 mm diameter alloy spindle option cranks from 120mm all the way to 155mm. Boost, Non-boost and even Super Boost options with narrow Q factors that are specified for 9,10, 11 and 12 spd drivetrains. Direct mount chainrings with options of 28T-36T. Weight is 556g (135mm/30T).
MSRP: $180 | Where to buy: XEON
Samox M7J Carbon Cranks
Samox takes it up a notch with 145 and 155mm Carbon Cranks for kids. A claimed weight of 380 grams, this carbon arm set comes with a 28.99 alloy axle making it the lightest option for the MTB shred kids. 3 bolt direct mount chainring (Sram style). If 145 is what you seek, get the Prevelo Heir cranks which are the same but with a 30mm spindle and 75 bucks cheaper.
MSRP: $375 (BB and chainring not included) | Where to buy: Samox
For those who are looking for the budget Goldix cranks. I just bought a full set including chainring and BB for just 35 dollars during the AliExpress anniversary sale.
It would be good to actual add the link to the product listing 🙂 just use one of the many coupon codes to get to the lowest price.
https://nl.aliexpress.com/item/1005005804968565.html
I bought 127mm ones to replace the 152mm cranks on my son’s Kona Honzo 20 inch.
Just got the Goldix cranks in 140 to replace the square taper ones on a Grand Canyon 24. Weight came in at 706g including their BB and 30T ring. A bit dissapointing given that the original set + Ti axle sq taper BB was 686g! Those Ti BBs from ali have been my goto upgrade for kids bikes before as they save ~145g on their own for ~$30-35.
Other than that things look good. The chainring is ever so slightly wobbly and chain engagement is kind of crude(?) but I don’t think it should be an issue. Used 2 BB spacers on the drive side and 1 on the non for the Canyons 68mm shell. Not sure if that was even enough as the axle bolt didn’t really push the crank arm snug against the BB but feels ok after tightening.
We have a virus20+. I would like to put a little longer crank arm and be able to change to chain ring. Do you know of a crankset in 130mm or shorter that this is possible without changing the square taper BB? I have found the Sinz cranks with 110BCD but smallest chain ring I found is 36T. I’m not against changing the BB just trying not to put to much into the bike. Comes with a 14-28T 7 speed cassette, a 32T chain ring and 114mm cranks.
Check out spawn site, I believe they list their square taper cranks.
Is it possible to use Prevelo Heir Cranks on the bmx racing bike? it seems to have different rear spacing settings.
All depends on the bottom bracket set up/spindle size & length/chainline but you can get pretty short bmx cranks that should work for most kids (we have seen as short as 125mm).
Alex, Aerozine have Xeon-A1 cranks down to 120 mm, that is the exact same brand and model as the stock cranks, so should be compatible.
https://www.aerozinebike.com/product/transmission/crankset/kid-bike-crankset/xeon-a1-mini-crankset-for-kidbike/
I’ve just brought my son a Commencal Clash 24 that has a pressfit BB92, do you have any recommendations for a lighter BB and crank setup??
Thanks!
We are not sure the weight of Aerozine set on the clash but the Trailcraft are most likely lighter. You will need to replace BB that fits a 24mm spindle however. Something like Shimano Dura-Ace BB92.
I got my son the same bike (Commencal Clash v2 24) and would like to replace its 145-mm Aerozine cranks with shorter ones (125-130 mm) and also replace the chainring with 28t instead of 32t in order to maintain the gearing ratio.
There is a ready solution from Aerozine, but it costs 180 USD + 40 USD delivery to Austria +20% import tax upon arrival. More than 250 bucks in total.
I would like to find something more reasonably priced.
Problem is, the bike has PF92 BB and cranks have 30 mm spindle. Most other more affordable options I see have 24 mm spindle.
I would like to avoid changing the BB.
Are you aware of some cheaper analogs of Aerozine with 125-130 mm crank length, 28t chainring, 30 mm spindle and fitting PF92 BB of the Clash?
Thank you for hints!
Anyone know if the Prevolo Heir described above will fit my son’s 2023 26″ reaper. It is a RaceFace Cinch and boost so I believe I need to buy the 3mm offset ring as well but the description above also advises a new bb. Not sure if I need the bb or not. Trying to reduce the crank arm down from description below. If not any other thoughts/experience? New to wrenching. Thanks:
Cranks & Chainring | Race Face Ride Cinch | 30T | 24mm Spindle | 165mm Crank Length
Bottom Bracket | Shimano SM-BBMT500
They should fit. Buy the 3 mm offset chaninring as you mentioned. You should be able to use existing BB as it is 24 mm spindle.
Thanks very much!
Are the chain rings that come with the Goldix narrow-wide? I can’t find anything that mentions it.
We went with a chainring from Prevelo as they offer loads of tooth choices and offsets for boost and non boost spacing. We ordered cranks without chainring.
My 10yo is coming off of a 24 in and I picked up a used XS specialized fuse for a great deal. She was too tall for her Woom 5 OFF the last month of summer, but really didn’t want to give it up. I’m a mediocre bike mechanic, so I’ll have my buddy do the install, but she clearly needs shorter cranks. The jump from 130mm on the woom to 170mm is ridiculous. I was going to get 150mm goldix with the BB, the BB on the bike is square taper 73mm.. can you confirm that it will work, or do I need something else? We cut down the handlebar width and the bike fit looks otherwise great, which I’m pretty happy about.
Should not be a problem with a threaded frame…
If only they hadn’t gotten stuck between customs and USPS, trying to decide if it’s worth ordering a second set, but I think probably yes, she’s not even 5 ft tall yet.
We had a friend order the Goldix Cranks. They seem nice, but there is a spacing issue. Spindle is long enough that there is excess spindle when used with a standard Shimano HTII bottom bracket. The bike’s bb shell is 68mm, I have a total of three 2.5mm BB cup spacers in, but crank still has about 3 or 4 mm of excess play. Trying to locate some 24mm id spacers for the spindle, but they seem to be out of stock. You get what you pay for.
Just received the 160mm Goldix crankset and BB to replace the 152mm Trailcraft cranks on his MTB since he’s also now running 160mm 105 and Rival cranks across his road and gravel bikes. Pretty well machined and light, but had had the same issue with spindle width on a Shimano SM-BB51 HT II bottom bracket. It would work with all three 73mm shell spacers in the 68mm BB shell his frame had but the chainline would have been way off. I noticed that the BB51 bottom bracket had a smooth, flat bearing interface while the newer ones and the one included with the Goldix crankset, have a slightly raised bearing interface. Using that included BB (actually pretty smooth and light compared to the Shimano), a single 2.5mm BB spacer on each side worked perfectly. Could have probably used some crank spindle wave or standard washers, but opted to give the Goldix BB a shot. I will say however, that the crankset I received had very tight / poorly cut threads, from the splines, to the pedal threads. Very difficult to initially slide the NDS crankarm on and install the pedals. So difficult in fact, I had to chase the pedal threads, from both the outside and inside of the crankarms.
Same issue using the BB supplied by Goldix. First, the spacers they provide compress under torque, so they instantly went into the bin. Using proper spacers, you still end up with roughtly a .5-1mm gap. A single spacer on the crankarm worked for me, and now everything is running smooth… but obviously annoying if you don’t have parts laying around.
Hi, I’m hoping someone has solved this issue before: trying to get shorter cranks on a 2021 RM altitude A50 – Shimano pressfit Bottom Bracket, Boost Spacing, Shimano Deore Cassette and Chain, XT Derailleur.
From what I can tell, all the readily available short cranks(prevelo, trailcraft, cleary, goldix) (I’m looking for 152mm) have the Sram style direct mount chainring and non boost offset (6mm) To use these shorter cranks with a boost shimano system I’ll need to get the crankset plus an aftermarket 3mm offset chainring that has Sram direct mount AND Shimano teeth. I’ve found a few from Oneup and Wolftooth.
Where you able to get this figured out
I discovered this same issue before ordering the Goldix cranks for my sons RM Reaper. Don’t want to pay for the oneup/wolftooth chainring so I’ve held off on ordering. Curious if/how you get it sorted.
Trying to figure out if the 127mm Trailcraft cranks/bottom bracket would work on a 2021 Norco Fluid FS1 20inch bike.
I am told the bike has a standard threaded BSA 73mm bottom bracket with a boost/3mm offset for chainring offset.
Would these cranks/bottom bracket work with this bike? Do I need to worry about the 49mm chainline or any other detail?
Its crazy that 20 inch bike has a boost rear but you should be able to make it work as the 140mm stock are samox cranks (samox makes “trailcraft” cranks). Fortuantly, chainline not a s big of a deal with a 10 spd cassette as a 12 spd. Plus the new fuid 20 still is a boost rear and uses 127mm cranks and they again are Samox. Might take some fiddling but you should be good. An yes, you will need a 3mm offset chain-ring, prevelo has them if Trailcraft does not.
Hi. I just ordered an XS Rocky Mountain Element A30 for my 9 year old, she’s an inch or 2 too short, but growing fast so decided to go to a good bike now. Their Website says the A30, even in XS has Shimano swore, 170mm cranks, 24mm.
How can i install smaller cranks on this bike? The bike is 2-3 weeks from delivery, so I’d like to order the crankset now too.
Also, I have opportunity to purchase 26” rims and tires that will fit, built by a dad in a similar situation. Realistically, how much will this drop the standover and ease of riding for this year? They are $600 but it may mean being comfortable on tbe bike this year instead of next.
Thanks. I love this site
Cranks are pretty easy to install, you can always take to a bike shop, its a quick job for them. 26 inch wheels would be a good idea as she is only nine and coming off 24 inch wheels.
This is all super great info – thank you! I’m considering buying the Goldix 140mm cranks for my son and his new 24″ Reaper (a few rides in and he’s constantly smashing pedals/cranks).
I believe they will fit (without needing to buy a new BB)….can anyone more mechanically inclined confirm they’ll work with the Reaper (and with the stock bottom bracket)? Has anyone swapped the cranks on this bike? I appreciate the input.
https://ca.bikes.com/collections/reaper/products/reaper-24-22-23
Yes, they will fit your reaper’s BB. These are also 24 mm axles like the stock cranks.
Thanks for the quick reply. Placing order now, I’ll report back with a review.
Wondering how long shipping for the Goldix cranks from China to the U.S. is taking on average…
less than two weeks for us.
Hi, any idea if the Goldix Cranks fit with a Frog bike road 70 2015 model?
I think it does but just want to make sure I dont miss anything.
I could not find the specs for the 2015 model but the Frog bike road 70, 2023 has this bottom bracket: Neco, square taper, 68/113.5, cartridge bearings
https://www.aliexpress.com/item/1005005335472302.html?
These are only a single chain ring, not sure you would want that on a road bike. You can get square taper kids alloy cranks on ali preprocess as well.
I was thinking that my 9 year old could use it for CX races as well, so thats why I am thinking 1×9 or 1×11 (need to change wheels for that)
I just ordered my daughter a yt jeffys 24″. Do you know what 145mm crank arms I could buy to use with the installed bottom bracket? or would any dub style crank arm work?
DUB BB’s are 29mm so just pick up the 24mm bottom bracket with new cranks. They are cheap, $20 at most. Only the carbon samox cranks are 28.99 spindle.
Great info. What is the Q-Factor on the Goldix 150mm?
Have not installed yet but they are going on a boost bike. I’ll try and measure….stay tuned.
Installed yet? Any clearance issues? Thanks!
I just received a set of Goldie 150mm arms. W-Factor = 172mm
Doing a new 24″ build for my 9 yo son who will race MTB. I want light weight and seems like the Goldix weights listed are similar to trailcraft (140mm) besides maybe the axle. Will goldix hold up ok durability wise? I love the price!
For sure, they are very similar alloy crank arms just one has the alloy axle and the other chromoly. I would think samox makes them both.
I reached out to Cleary and they gave me the mass info for the scout crankset. The 140mm with chainring and BB weighs 1 lb. 9 oz. Exact same weight as the goldix.
pretty sure these are all made by Samox.
Where on the earth did you find 115 mm cranks for the 20″? I just picked up a 20″ Commencal Ramone, and it’s perfect for my daughter in every aspect but the cranks, which are 145mm, waaaay too long. I’m on the struggle bus trying to figure out a shorter option for her.
https://s.click.aliexpress.com/e/_DENzP7L
We bought them in 150mm length with BB. They are legit. Shortest is 110mm.
Anything out there for about 50 bucks?
don’t think so but try alibaba…
Prevelo Heir 120mm $60 https://m.pinkbike.com/buysell/3555115/
Aliexpress
Goldix and Cruz Bikes brands have 150-165mm cranks.
They use HTII BB (not GXP though that is what is stated). $35usd. SRAM direct mount chainrings. Not for heavy riders or enduro/dh riding.
They actually go right down to 127mm…they appear to be the samox cranks like that of the re-branded Prevelo and Trailcraft. Look like the Steel axle of the Prevelo cranks not the alloy axel of the Trailcraft.
Any idea what the weight is on the 127mm Trailcraft cranks? Looking to see if I will save a significant amount of weight over the cranks on my sons Yama Jama.
Not sure about the 127’s but they do use an alloy spindle so will be lighter as I believe spawns are steel (double check this though), probably 80-100 grams lighter. Just email Trailcraft and they can give you weights for 127.
Thank you for this article and all the helpful replies above. I’ve bought the goldix cranks and bottom bracket. I’m replacing a square taper and have what I need to remove this, but I’m wondering what tools I will need to install the goldix bottom bracket and crank? Thanks
You will need appropriate BB wrench and some allan keys, very easy install.
Hi,
Hello
Hope makes cranksets for kids ($$$) :
https://www.bike-components.de/en/Hope/Kids-No-Spider-Crank-p74887/
and vpace too, like trailcraft :
https://www.vpace.de/vpace-leichte-kinderkurbel?c=25
And hope have a new classic evo crankset size in 155 !
Regards
Pierre
Do you think it’s time to revisit ideal crank lengths for kids mtb? I think they’re still too long. Have you compared Lennard Zinns formula to suggested inseams for bikes? I like 115mm and under for 20” and 130mm and under for 24” bikes. This would help kids get on bigger wheels sooner too.
Totally agree. Especially when you can design more BB drop and make smaller fitting 20 and 24 inch frames to gain the benefits of bigger wheel size. We primarily ride full suspension mountain bikes and our kids currently have 115mm on their 20 inch bikes, 120mm on 24 inch bike, and 145mm on 27.5 bike. We ride shorter cranks too. One of us is 5’8 and runs 160mm and the other is 5’11 and runs 165mm. The premium kids brands have done really well bringing down length but probably could go a bit further depending on geo/fit of bike.
I’m 6’1 and run 165mm. No downsides.
Some more options for short cranks.
Many Sizes, light, bling bling ($$$): https://ride5dev.com/collections/cranks/products/new-crank-product-page?variant=41500200960162
A “Robust” option for enduro racing groms that may have broken the Trailcraft Spindle interface: https://canfieldbikes.com/collections/cranks-chainrings/products/canfield-bikes-am-dh-cranks?variant=32779298635851
Many size options, adjustable by up to 5mm. Additional ~100 grams over Trailcraft: https://www.aerozinebike.com/product/transmission/crankset/for-mtb-bike/xeon-series-for-mtb-bike/aerozinexeon-a1-crankset/
If you read the Trailcraft site it says “BB Weight in specs below” so you need to add 113g for the total system weight
Thanks for the links! Just ordered some 140mm prevelo’s for my son
I recently bought Commencal Clash 20, but it has bb92 pressfit 30mm bottom bracket, and unfortunately 135mm cranks, it is too long for me. Are there any options for bb92 with 30mm spindle shorter than 135mm?
We are not aware of any 30mm spindle cranks under 145. You can always switch out BB for 24mm…
Alex, Aerozine have Xeon-A1 cranks down to 120 mm, that is the exact same brand and model as the stock cranks, so should be compatible.
https://www.aerozinebike.com/product/transmission/crankset/kid-bike-crankset/xeon-a1-mini-crankset-for-kidbike/