Affordable "Cruzbike" Short Cranks

LarryOz

Cruzeum Curator & Sigma Wrangler
I can't stop thinking whether 165mm crankarms are a good compromise.. but that's for a different time.
The real key to whether 165 would be good for you is how much your knee bend is on your back-stoke. You want you knee bend to be about 90 or more. Anything less is ultimately bad for you knees, and your power making ability. When you knees are bend more than 90 degrees you cannot really make good power until they open up to that point - which will only happen as you continue pedaling - but when that point is reached you have lost a significant percentage of that "10-2" range where you make most of it. Not to mention your knees hurt if you try and push hard when compressed at more than 90 degrees. Hope this helps.
 

ak-tux

Zen MBB Master
The real key to whether 165 would be good for you is how much your knee bend is on your back-stoke. You want you knee bend to be about 90 or more. Anything less is ultimately bad for you knees, and your power making ability. When you knees are bend more than 90 degrees you cannot really make good power until they open up to that point - which will only happen as you continue pedaling - but when that point is reached you have lost a significant percentage of that "10-2" range where you make most of it. Not to mention your knees hurt if you try and push hard when compressed at more than 90 degrees. Hope this helps.
To add to what Larry said, I came across the online calculator below, though Iam yet to try anything shorter than 165mm (which came with my S40). Iam currently using 170mm cranks becuase I got a crank based powermeter on it.


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ak-tux

Zen MBB Master
I finally recieved some "Goldix" 150mm cranks from AliExpress. Costed me $40 total (inclusive of Shipping to Kenya). Quite affordable indeed.

First impression: they look strong and well built. The color is a mat finish. Just functional not flashy.
The spindle is standard 24mm for Shimano HollowTechII bottom brackets. The cranks install just like Shimano ones, with two pinch bolts at 12-14Nm.

The downside is that they are designed to fit mountain bikes and therefore the Q factor results in a slightly wider stance, about +5mm. Not a show stopper though. (When I started pedalling, I did notice this change for a few minutes then I adapted.)

They required some spindle spacers in order to fit properly and apply the necessary bearing preload. I added 3 aluminium spacers (1mmx24mm) between the left crank and the BB. (I had previously acquired these for another project from https://www.aliexpress.com/item/1005003657191586.html)
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I decided to install it on my old homemade recumbent. (I don't want to change my S40 at the moment becuase it has a 170mm left crank based power meter that I have fined tuned to match my fit. )

For the chainrings, I had an old GXP/SRAM Rival 50x34 direct drive set that I bought used from a friend. It fits perfectly on the Goldix.

I first tested it on a turbo trainer to see how it feels. I was afraid 150mm will be too stubby and even comical. However, surprisingly, the 150mm felt very natural! I must admit, I even liked them!:) It feels like one is applying a continuous force all around the pedal stroke unlike the pulse like input feeling of the longer cranks. Hmmm, interesting.

The assesment is positive so far.
Next step, I will fine tune it further and try it outside on the road.
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Don1

Guru
Just got some carbon 150mm cranks of aliexpress. Lease cs-01. 220aud. They look amazing, yet to try them thou. Unfortunately they'll go on the roadbike for an alpine grand fondo. I was able to beat several 10year old pr's on my local hills with 155's and 6kg heavier, so I'm hooked on short cranks
 

ak-tux

Zen MBB Master
Just got some carbon 150mm cranks of aliexpress. Lease cs-01. 220aud. They look amazing, yet to try them thou. Unfortunately they'll go on the roadbike for an alpine grand fondo. I was able to beat several 10year old pr's on my local hills with 155's and 6kg heavier, so I'm hooked on short cranks
Cool! Maybe share the AliExpress link too?
 

Rampa

Guru
Those Goldix are the same ones I got. But I went with 140mm. My legs are kind of short for my height. But same feeling. It just rotates smoother and spins up so fast! :)
 

kizarmynot

Well-Known Member
To add to what Larry said, I came across the online calculator below, though Iam yet to try anything shorter than 165mm (which came with my S40). Iam currently using 170mm cranks becuase I got a crank based powermeter on it.


View attachment 17756
Any idea what the high/med/low BB means? All entries are green (good?), but that's 4 different crank lengths between them.
 

LarryOz

Cruzeum Curator & Sigma Wrangler
Any idea what the high/med/low BB means? All entries are green (good?), but that's 4 different crank lengths between them.
This is talking about the height of the BB in relation to the ground (or your seat bottom). A "low" BB would probably have your BB below your seat and would feel rather odd compared to how most Cruzbike BB's are fit to riders. The only way you get a really low BB on Cruzbike is if you have really long legs and a really short chain stay. Usually you want the BB to be about 5-6 inches above the bottom of your seat. And you never want it so high that your boom in angled down from the BB to the handlebar.
 

ak-tux

Zen MBB Master
Any idea what the high/med/low BB means? All entries are green (good?), but that's 4 different crank lengths between them.
Yes, basically, what @LarryOz said.

Generally, all Cruzbike S40s with the standard (450mm) chainstays that come with the bike, for an average rider (height 178-180cm), will place the bottom bracket (BB) just slightly above the level of the seat base. This would qualify as a med BB. If however you modify the bike and put longer chainstays(which cruzbike also sells) then the BB will qualify as high.

On the other hand, I think Cruzbike V20 will probably qualify as having a high BB for an average rider.

For my dimensions (for an S40 with standard chainstays), both 150mm and 145mm cranks would fit me. However according to the calculator the 150s would give me a knee angle of about 85 degrees, which is what it recommends.1734505033151.png
 
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ak-tux

Zen MBB Master
Happy new year, good people!

A brief report on my short cranks "experiment" :) . So far, I have done about 350Km on these 150mm "Goldix" cranks on my homemade recumbent. The test terrain was rolling flat with some moderate steady climbs ( less than 6%). (I will install on my S40 once I can afford a compatible spider-based power meter)

It's hard to make an objective comparison without a power meter. However, based on feel, my take is:
1. They spin up quick from a dead stop or after a corner.

2. They hold speed really well on flat, rolling terrain.

3. They really feel nice on the knees. The knee does not bend as much on the, very brief, dead spot . (This is the primary reason I will eventually move my S40 to 150mm cranks). The 165mm cranks that originally came with S40 cannot compare to these sweet stubby cranks.

4. Naturally, it's easier to hold a higher cadence.

5. They place the knees further away from the handlebars, making it easier to fit the bike. It allows the hands to have a good natural reach, unrestricted.

6. The climbing requires gears to shift sooner because the cadence drops faster as the grade increases compared to the 170mm. (Currently on 50/34 with 11-34 cassette)
For this reason, I think they will be better on a 1x groupset because of the greater spread of gears on one chainring.
I think on the 170mm cranks (currently on my S40), I can stay on a gear a bit longer before making a shift becuase of the slightly higher torque.

7. Lastly, it feels like one is applying force continously with mimimal dead spots on the pedal cycle. For this reason, the perceived peak power "feels" really good (especially when doing a bridging technique), and I dare say, maybe marginally higher than on my 170mm cranks. However, holding sustained steady power on a climb is another issue. The percieved exertion feels higher on a climb. I think it is fair to say that one still requires practice and an adaptation period to get optimum steady power on a sustained climb.


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RossK

New Member
I'm planning to import a new S40 frameset to the UK and I'm lining up all my parts for the build.

I'm 5'7" and, after researching, I realise my 170mm crank length I've been riding for decades on DF bikes should probably translate ideally to 150mm for the S40. Given that I'm a beginner I feel I should go straight to the short crank option rather than suffer the drawbacks of 170s while learning and then have to adapt to shorter later.

I also note that future Cruzbike S40s will ship with 145mm. So it's a real thing!

This thread has been invaluable and quite fascinating. I love the idea of the cheap and lightweight Goldix cranks which are Hollowtech2 compatible but I'm slightly concerned that they're described as kids' cranks, in respect of durability.

What is the longer term experience of you guys that have ridden on these sorts of cranksets for a while? Do you love them?

Other questions....

Are narrow wide chainrings available?
Are spiders available to make a super compact (28-44) using standard 110bcd and 74bcd rings?
Are 150mm cranks the sweet spot for my height?

Thank you for any information!

Ross.
 

Rampa

Guru
What is the longer term experience of you guys that have ridden on these sorts of cranksets for a while? Do you love them?
I've been riding these Goldix cranks for years now. They are totally great. I do have a narrow-wide chain ring. You may need to search a bit to find larger than around 38 teeth though. Amazon or Aliexpress are your friends here. I have found both a 40 and 44 direct-mount ring with some searching.

If you search "Folding Bike Crankset" on Amazon, you will find a bunch of shorter cranks, including the Goldix.
 

RossK

New Member
I've been riding these Goldix cranks for years now. They are totally great. I do have a narrow-wide chain ring. You may need to search a bit to find larger than around 38 teeth though. Amazon or Aliexpress are your friends here. I have found both a 40 and 44 direct-mount ring with some searching.

If you search "Folding Bike Crankset" on Amazon, you will find a bunch of shorter cranks, including the Goldix.
Thank you, that's great to hear!
I managed to get a 40t narrow-wide ring in the 6mm offset version which gives the best chain line, I understand. Total price only about £40 from AliExpress, incredible value!

I've been a bike geek for decades but all this new stuff for Cruzbikes like the short cranks is fascinating!
 

ak-tux

Zen MBB Master
What is the longer term experience of you guys that have ridden on these sorts of cranksets for a while? Do you love them?

Other questions....

Are narrow wide chainrings available?
Are spiders available to make a super compact (28-44) using standard 110bcd and 74bcd rings?
Are 150mm cranks the sweet spot for my height?
I love my "Goldix" "Kids" 150mm cranks!! :)

Yes, I have found all the narrow-wide chainrings I need on AliExpress that are intended for 3bolt SRAM compatible direct mounts
I have also found 3-bolt SRAM compatible Spiders and powermeters.
My 150mm cranks have worked for me without any issues.

Below shown is my 2019 S40 with 150mm cranks from AliExpress fiited with Magene P505-S1103 spider powermeter for 110mm chainrings.

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