Short crank questions answered here

[Jim Parker]

Cruzbike recently ordered a quantity of high quality short cranks made by Croder Cycling in Taiwan. These are now listed for sale on our website.
We have been looking for high quality lightweight 145mm cranks for many years, and then came across these cranks at the big bicycle show in Taipei, Taiwan earlier this year.

Why are short cranks better?
This blog gives nine reasons. If you haven't already read it, please do so.

What type of interface is the crankset compatible with?
The SRAM 8-bolt standard. Any chainring, power meter, or spider compatible with this standard will fit.
Below are three example photos of the SRAM 8-bolt interface.



Why didn't you put 145 mm cranks on stock bikes before this?
Because quality ones were not available.

Will all Cruzbike models come with 145mm cranks in the future?
Yes, to the extent that we can source them. There are bicycles already in production with longer cranks, but we will make every effort to source future models with the 145mm cranks.

Can you put a double (2x) chain ring on these cranks?
Yes. 1x or 2x is fine. install your chainring(s) of choice on your (compatible) spider of choice.

Can I order directly from Croder?
Sure. Check out their cranks and accessories on their website.

How will these cranks affect my bicycle's fit?
That depends on the length of your old cranks. If they are 165mm, for example, then you may need to extend the boom out 20 mm to keep the same x-seam (165mm - 145mm = 20mm). In practice, some people don't even notice the difference and make no adjustments.

Will these work on my old Cruzbike?
Yes. All models of Cruzbike except the V20c use a BSA bottom bracket. If you have a V20c, then order a set with the T47 BB. If you have anything else, order it with the BSA BB.

Are they hard to install?
It's probably best to have your local bike shop do it, but if you have the proper tools, it is not that hard. We will be putting out an instructional video soon to assist you or your local mechanic with the installation.

 

[Robert Holler]

These cranks are sweeeeeeeeeeeet. Feel free to ask me any Q's here.

 

[ak-tux]

These cranks are sweeeeeeeeeeeet. Feel free to ask me any Q's here.

Is there an adaptation period? When I first moved from 170mm cranks to just 165mm(stock S40 cranks), it felt a bit harder to push (naturally becuase the leverage is reduced) but it took a while to get used to it. Climbing did not improve, despite the noticeable increased cadence (that new cadence was amazing by the way!). I ended up putting back my trusty 170mm cranks.

Maybe I just needed more time but I gave up too soon? Or may be it needed a cleat postion change further torwards the mid-foot together with the shorter crank. I don't know. Moving my cleats an inch behind the ball of my food seems to have done the magic for me.

 

[Robert Holler]

I would say that there is a bit of an adaptation period but for me it wasn't too bad. But I ride many different bikes that have cranks ranging from 145 to 155 to 165 to 172.5's and usually do not ride any one bike for extended lengths of time during the Sean... so I change up every ride or two. If you are used to one bike and its fit that might make for a bit longer time to get used to it.

 

[IyhelM]

Will you change the default chainrings accordingly?

 

[Robert Holler]

The ring that the cranks come with is a smaller 38T ring - mostly aimed for the current set of Q45's and S40's where people want a bit lower gearing. The cranks are GXP 8-bolt standard though, so there are many options for other rings or doubles, etc.

We will not be carrying those, but they are starting to pop up all over, even on Amazon in various sizes and arrangements.

 

[CruzLike]

Currently riding a 165 crank with a compact double. (32/50) How much will I feel it when I'm climbing a hill and gear limited? Will it be just 145/165 = 87%?

On the flats this is a win. Your knees will not rise as high during the pedal stroke. This helps aero and someone with sensitive knees.

 

[DavidCH]

I haven't taken a good look at the scientific paper that says 145 is the best power sized crank. The best way of pedalling a bike is by applying force on the downstroke but in order to get those power numbers for the 145... they must be healing the peddle stroke?

 

[Black Hawk Down]

This sounds interesting. The blog post says that to keep the same gain ratio when going to smaller cranks, you need to reduce the number of teeth in the chain ring. I assume that this is necessary to have the same climbing ability. But what does it do to top end speed? Going to a smaller chain ring would seem to reduce your top end speed at the same RPM.

I have 155 mm cranks on my Q45. My other Cruzbikes have 165 mm. I noticed that I could no longer climb two of the hills in my daily ride when on the Q45, that I was able to do on the V20 and S40. In all cases, my chain rings are 40 teeth with the same cassettes. However, my top end speed on the Q45 is the same as my other bikes with the same drive train. How much would I have to reduce my Q45 chain ring to get the same climbing ability as the other bikes? Would that reduce my top end speed? I would not like that.

I am interested in buying these cranks for my V20, which now has 2 x 11 Shimano Ultegra 165 mm 34/50 cranks. My cassette is 11x42. Any idea what chain rings I would need to compensate for the shorter cranks? I'm not sure that I can find chain ring sets that are smaller than these.

Thanks!

 

[IyhelM]

@Black Hawk Down you can find « subcompact » chainrings in 30-46 or 32-48 from FSA or Shimano (GRX series) and most others.

 

[Black Hawk Down]

@Black Hawk Down you can find « subcompact » chainrings in 30-46 or 32-48 from FSA or Shimano (GRX series) and most others.

Thanks. I'll look into it.

 

[ak-tux]

This sounds interesting. The blog post says that to keep the same gain ratio when going to smaller cranks, you need to reduce the number of teeth in the chain ring. I assume that this is necessary to have the same climbing ability. But what does it do to top end speed? Going to a smaller chain ring would seem to reduce your top end speed at the same RPM.

I have 155 mm cranks on my Q45. My other Cruzbikes have 165 mm. I noticed that I could no longer climb two of the hills in my daily ride when on the Q45, that I was able to do on the V20 and S40. In all cases, my chain rings are 40 teeth with the same cassettes. However, my top end speed on the Q45 is the same as my other bikes with the same drive train. How much would I have to reduce my Q45 chain ring to get the same climbing ability as the other bikes? Would that reduce my top end speed? I would not like that.

I am interested in buying these cranks for my V20, which now has 2 x 11 Shimano Ultegra 165 mm 34/50 cranks. My cassette is 11x42. Any idea what chain rings I would need to compensate for the shorter cranks? I'm not sure that I can find chain ring sets that are smaller than these.

Thanks!

I think, if the leg speed remains the same, then the shorter the crank the higher the cadence. So, to compensate for the increased cadence, for the same power, the chainring has to get smaller. But it is not clear by how much. (Probably there is a good gear calculator online that we need to use. Anyone?). Additionally, there has to be a boom extension to match the reduced cranklength.

As for climbing, if the chainring is reduced to compensate for the reduced torque of the shorter crank , then theoritically we should be able to produce the same power at a higher cadence. However in practice, I think it must require some adaptaion period IMHO. I mean, surely, after all the years we may have spent pedaling on longer cranks, it's got to feel a bit strange at first.

 

[Karl42]

I think, if the leg speed remains the same, then the shorter the crank the higher the cadence. So, to compensate for the increased cadence, for the same power, the chainring has to get smaller. But it is not clear by how much. (Probably there is a good gear calculator online that we need to use. Anyone?). Additionally, there has to be a boom extension to match the reduced cranklength.

As for climbing, if the chainring is reduced to compensate for the reduced torque of the shorter crank , then theoritically we should be able to produce the same power at a higher cadence. However in practice, I think it must require some adaptaion period IMHO. I mean, surely, after all the years we may have spent pedaling on longer cranks, it's got to feel a bit strange at first.

As someone who has tried different crank lengths on my recumbent, I can certainly attest that the shorter cranks need a lower gear for the same climbing effort. That can be achieved with a smaller chainring in the front, or a larger gear on the cassette.
As for how much, that probably comes down to personal experimentation. If you don't already use the extreme ends of your current gearing setup, you can probably just keep using it.
Here is an article with some specific recommendations (however, in practice I would only use that as a starting point to try out what works for me personally): https://bikepacking.com/gear/crank-length-test/

To quote:

Gearing​

Shorter cranks require more force to move the same gear at the same speed, and while not everyone will require a smaller chainring when moving to shorter cranks, I think most bikepackers will. Appleman recommends trying a 1/2 (one half) percentage change of crank length reduction in gearing. “For example, going from 172.5 with a 40t chainring to 155mm cranks is a ~11% change. Finding a gear that is about half of that 11% would be a 38t, a 5% difference. Or, say you’re currently riding a 32t chainring, then a 30t would provide a 6% reduction in gearing.”

 

[ak-tux]

As someone who has tried different crank lengths on my recumbent, I can certainly attest that the shorter cranks need a lower gear for the same climbing effort. That can be achieved with a smaller chainring in the front, or a larger gear on the cassette.
As for how much, that probably comes down to personal experimentation. If you don't already use the extreme ends of your current gearing setup, you can probably just keep using it.
Here is an article with some specific recommendations (however, in practice I would only use that as a starting point to try out what works for me personally): https://bikepacking.com/gear/crank-length-test/

To quote:

Gearing​

Shorter cranks require more force to move the same gear at the same speed, and while not everyone will require a smaller chainring when moving to shorter cranks, I think most bikepackers will. Appleman recommends trying a 1/2 (one half) percentage change of crank length reduction in gearing. “For example, going from 172.5 with a 40t chainring to 155mm cranks is a ~11% change. Finding a gear that is about half of that 11% would be a 38t, a 5% difference. Or, say you’re currently riding a 32t chainring, then a 30t would provide a 6% reduction in gearing.”

Thanks for the link! Great info there!

 

[Karl42]

I just found the original website that the article I linked in my last post refers to: https://www.applemanbicycles.com/resources/riders-guide-to-crank-length/
It is an in-depth guide to crank length. Well worth reading.

 

[ccf]

When I switched from 172.5 down to 145, I compensated by switching the cassette from 36t up to 42t. That works well.

 

[ccf]

Cruzbike recently ordered a quantity of high quality short cranks made by Croder Cycling in Taiwan. These are now listed for sale on our website.
We have been looking for high quality lightweight 145mm cranks for many years, and then came across these cranks at the big bicycle show in Taipei, Taiwan earlier this year.

Why are short cranks better?
This blog gives nine reasons. If you haven't already read it, please do so.

What type of interface is the crankset compatible with?
The SRAM 8-bolt standard. Any chainring, power meter, or spider compatible with this standard will fit.
Below are three example photos of the SRAM 8-bolt interface.
View attachment 17285
View attachment 17283 View attachment 17284

Why didn't you put 145 mm cranks on stock bikes before this?
Because quality ones were not available.

Will all Cruzbike models come with 145mm cranks in the future?
Yes, to the extent that we can source them. There are bicycles already in production with longer cranks, but we will make every effort to source future models with the 145mm cranks.

Can you put a double (2x) chain ring on these cranks?
Yes. 1x or 2x is fine. install your chainring(s) of choice on your (compatible) spider of choice.

Can I order directly from Croder?
Sure. Check out their cranks and accessories on their website.

How will these cranks affect my bicycle's fit?
That depends on the length of your old cranks. If they are 165mm, for example, then you may need to extend the boom out 20 mm to keep the same x-seam (165mm - 145mm = 20mm). In practice, some people don't even notice the difference and make no adjustments.

Will these work on my old Cruzbike?
Yes. All models of Cruzbike except the V20c use a BSA bottom bracket. If you have a V20c, then order a set with the T47 BB. If you have anything else, order it with the BSA BB.

Are they hard to install?
It's probably best to have your local bike shop do it, but if you have the proper tools, it is not that hard. We will be putting out an instructional video soon to assist you or your local mechanic with the installation.

@Jim Parker can you provide a recommendation for a 2X spider that will fit these cranks and that will support chainrings smaller than 50/34?

 

[Robert Holler]

@Jim Parker can you provide a recommendation for a 2X spider that will fit these cranks and that will support chainrings smaller than 50/34?

With their adapter (SRAM 8 bolt) like the link below nearly any stock rings can be used:

SPIRIT Spider 5-Arm

TYPE | SPIDER 5-ArmWEIGHT | 49 g/pair (Road)MATERIAL | AL7075-T6 PROCESS | Full CNC MachinedB.C.D. | 110 mmCOMPATIBILITY | STANDARD 5-ArmSPIRIT is the modular crankset that allows you to select the crank arms, axles, spiders, and

www.crodercycling.com

They also have doubles:

Gearmate Chainring Standard 5-Arm

CRODER® all new Gearmate series, made of AL7075-T6 aluminum material by full CNC machined are not only solid, but also durable. We find benefits of super compact, especially for 46T/30T and 48T/32T. By using this, cyclists can cl

www.crodercycling.com

They have a 46/30 even.

 

[Black Hawk Down]

I most definitely saw a loss in climbing ability when I moved from 165 mm to 155 mm on my Q45 cranks. There's two hills I used to be able to grind hard to get up that I can no longer climb. My cassette is already maxed out at 52t and my chainring is 40t, so I'll have to reduce it. The bigger problem for me is the V20 where I have a 42 on the back (can't go higher) and 34/50 chain rings. For this bike, I'm not sure if I will need to change the chain rings if I go to 145 mm cranks, but I'm guessing I will. I will need to get them with a return policy in case they don't work out and I have to change them.

Thanks @Karl42 for the article link. I will read it later today. Thanks @Robert Holler for the chain ring links.

 

[DavidCH]

I think, if the leg speed remains the same, then the shorter the crank the higher the cadence. So, to compensate for the increased cadence, for the same power, the chainring has to get smaller. But it is not clear by how much. (Probably there is a good gear calculator online that we need to use. Anyone?). Additionally, there has to be a boom extension to match the reduced cranklength.

As for climbing, if the chainring is reduced to compensate for the reduced torque of the shorter crank , then theoritically we should be able to produce the same power at a higher cadence. However in practice, I think it must require some adaptaion period IMHO. I mean, surely, after all the years we may have spent pedaling on longer cranks, it's got to feel a bit strange at first.

On android there is an app called GearCalculator which I use quite often