Levo SL Gen 1 Levo SL 1.1 Cranks vs Vado/Creo SL cranks

[G-Sport]

My levo SL (and my knees) could do with shorter aluminium cranks. Does anyone know if the Vado/Creo SL cranks are too different to the Levo SL ones to fit?
My plan is to buy 175mm Vado/Creo cranks and cut them down to 150mm (or thereabouts assuming this leaves a reasonable amount of material between the pedal hole and the scallop cavity on the back of the crank arm).
BUT I cant find any info on differences between the two cranks, I imagine that the road versions aren't as beefy but cutting the length down 14% should reduce the stress a lot and I am not super heavy, but if the Q factor is very different that may cause issues with fit. Does anyone know at all?

 

[Semmelrocc]

What do you mean by "cut them down"?
Why not buy a shorter version of the cranks like these 160mm ones, which Praxis apparently seem to make?

 

[G-Sport]

Drill and tap a new pedal thread 25mm nearer the BB and machine the end off in a nice curve.
The 160mm ones have been temporarily sold out for a year now so I have to try to work with what little is available. Also that would only be a 5mm decrease on the 165mm that came stock.

 

[Semmelrocc]

I don't think that would work, especially as the material towards the middle of the crank arm is way thinner, see picture.

And for it to work in theory, you would have to take the longest available crank arm so your new thread doesn't overlap with the original one, wouldn't you?
Anyway, the 160mm version doesn't seem to be sold out everywhere, I just found it at Hibike, see link.

 

[G-Sport]

Thanks for looking but for me that comes up as out of stock too (?). Interestingly though it does list it as suitable for either Levo Sl or Creo SL s so that suggests compatibility the other way too.
Yes, I need to get the long road version but then 175mm lets me cut to 150mm no problem, 25mm difference and the pedal thread is about 14.5mm on the major diameter so that leaves 10.5mm of material around the new thread which should be plenty.
Running out of full thickness arm is a slight worry but photos look like the road versions have enough space.

As long as they have used the same forging for all the lengths then this photo of a 165mm suggests that there should be enough material (since the existing pedal hole would be 10mm further out than in this shot). If they have used a different forging for the 175mm to save weight then it will be a bust.

 

[G-Sport]

Praxis USA just came back to me and the Q factor is identical so I'm going to order a set and see if it looks like there is enough material where I need it.

 

[Semmelrocc]

Could they give you an update on general availability?
Personally I still can't imagine your hack (or bodge) will work or be reliable in the long term. But please keep us updated with pics.

 

[Zimmerframe]

Someone did do this before, but I think it might have been on bafang cranks when there were no options.

Seemed to work.

 

[G-Sport]

Someone did do this before, but I think it might have been on bafang cranks when there were no options.

Seemed to work.

No options for cranks shorter than 160mm (which is what I think I need/kneed) and even the 160's are proving hard to track down now. As the motor has been replaced by the SL1.2 now with a different interface, I am worried that Praxis wont be inclined to do another run of the aluminium cranks (with no prospect of a big OEM order) when they can just force existing customers to buy the carbon ones.

 

[G-Sport]

Could they give you an update on general availability?
Personally I still can't imagine your hack (or bodge) will work or be reliable in the long term. But please keep us updated with pics.

It's not really a hack or a bodge, just replicating what they do in production as a one-off.

 

[Zimmerframe]

No options for cranks shorter than 160mm (which is what I think I need/kneed) and even the 160's are proving hard to track down now. As the motor has been replaced by the SL1.2 now with a different interface, I am worried that Praxis wont be inclined to do another run of the aluminium cranks (with no prospect of a big OEM order) when they can just force existing customers to buy the carbon ones.

I think even the Forx Hex1's are only available in 160's

HEX1 | 160mm E-Bike MTB Cranks | FORX.bike

HEX1 cranks are designed for Specialized SL M30 1.1 motor, Levo SL and Kenevo SL E-bikes. Check out technical info here.

forx.bike

Presumably because it's a lightweight they assume you need the extra leverage which you don't necessarily need on a Full Fat.

 

[G-Sport]

They are also £300...

 

[G-Sport]

Could they give you an update on general availability?
Personally I still can't imagine your hack (or bodge) will work or be reliable in the long term. But please keep us updated with pics.

Cranks arrived, they looked good, plenty of space for adding a new pedal hole. Little bit lighter than the stock MTB 165mm ones but since shorter means less leverage (in some modes) I think they should be fine once shortened.

So went ahead and cut them down to 150mm.

Very happy with how they came out. Not ridden them properly yet but jibbing about on the bike they feel lovely, I'm very excited to try cranks proportional to my height (5'7" ish).

Probably could have saved a bit more weight off the end but I wasn't in this for the weight saving and the 70g just about balances s the new chain/bash-guard I made last week..

 

[G-Sport]

My cut down cranks are still running great and I really like them so I wont be changing.
But, for the benefit of anyone else searching, had an email yesterday that the 160mm ones are back in stock with the UK distributor, though the link they sent still shows them as out of stock:-

Alloy - Upgrade Bikes

www.upgradebikes.co.uk

 

[crawfishoo]

Great work G-sport! I'm going to do the same thing for a set of cranks for my son's SL. What PN did you use, they are from specialized I'm guessing? Direct from praxis only has 170mm option. And how short do you think is possible? Ideally I would get 130mm cranks for my son but nothing exists for M30 interface. Hoping 140-145mm is possible with these arms.

 

[G-Sport]

This is what I bought.

S191600012 Specialized CRK Turbo SL 1.1 Road/Active 175mm L/R Arms Alloy Praxis

They are still going strong and I am still very pleased with them.
If you look at the photos above you can see that the original 165mm arms have an oval marking and the end of the crank arm comes quite close to it, the 175's have a similar oval but the pedal hole is at the outermost position. So my guess is that they have one forging for the MTB cranks and another for the road and then the only difference will be where they put the pedal hole and cut it down to.
I did 150mm and you can see in the photos that that is about as short as it is probably sensible to go for an adult, but 145mm would probably be OK for a lighter rider. If you are going 145mm then 170mm would probably be OK as a starter too as you would have shifted the hole the same amount so should be clear of the old hole. Just try to find a picture of the back before you buy them.
Good luck.

 

[crawfishoo]

G-sport,

Would you be willing to measure the length between the crank center and the end of the scallop on the backside of the arms? Wonder if the road vs the mountain arms are different. Based on the pictures it looks like the road arms theoretically could be made shorter, but that might just be an illusion. I want to start with the arms that have the shortest scallop. Thank you.

 

[G-Sport]

G-sport,

Would you be willing to measure the length between the crank center and the end of the scallop on the backside of the arms? Wonder if the road vs the mountain arms are different. Based on the pictures it looks like the road arms theoretically could be made shorter, but that might just be an illusion. I want to start with the arms that have the shortest scallop. Thank you.

Can do if you really want, fairly sure the road have a shorter scallop but don't think there is much in it.

The main concern is that there isn't already a pedal hole too close to where you need to put the new one.
Going from 175mm to 150mm only gave a hair over 10mm wall between the original pedal hole and the new one. So I think you need to shorten at least 25mm on the original length to have a nice bit of material there.
I think you could do 145mm OK with the road cranks but you want at least the 170mm length ones.

 

[crawfishoo]

I would be comfortable putting 1/3 of the hole into the scallop. The crank arm on the SL kids are that way, specialized made them as short as possible without changing the forging. If I can get 5mm shorter with road vs MTB cranks that's worth it to me.

Looks like i can shorten my current MTB 170mm cranks about 25mm, that would give 145mm. But would still really like to be closer to 135 so hoping the road crank scallop is shorter.

 

[crawfishoo]

G-sport. Yes if have the chance to measure your road cranks I would really appreciate it. The MTB cranks are 142mm from spline center to end of the scallop. Really hoping the road cranks have a shorter scallop.

 

[G-Sport]

G-sport. Yes if have the chance to measure your road cranks I would really appreciate it. The MTB cranks are 142mm from spline center to end of the scallop. Really hoping the road cranks have a shorter scallop.

Sorry for the delay.
Road cranks are a tiny bit better for your purposes.
From the 36mm raised boss around the axle the scallop on the road cranks extends to 121mm.
On the MTB cranks this dimension is 124mm
So from axle centre should be 139mm and 142mm respectively.
The end of the scallop is quite gentle on the road cranks too so you could overlap it a little.
Hope this helps.

 

[crawfishoo]

Thank you for checking, that is exactly the details I needed. The 3mm difference between MTB and road crank scallop is not enough for what I want. Guess I will bite the bullet and machine the ends off, mill a pocket, and weld in a puck at 135mm. Was hoping for an easier solution but don't think it's an option.

 

[G-Sport]

Thank you for checking, that is exactly the details I needed. The 3mm difference between MTB and road crank scallop is not enough for what I want. Guess I will bite the bullet and machine the ends off, mill a pocket, and weld in a puck at 135mm. Was hoping for an easier solution but don't think it's an option.

I have successfully had 3d printed aluminium arms made to fit the spline well. You can do hollow section and just the length you need that way.

 

[KnollyBro]

I have successfully had 3d printed aluminium arms made to fit the spline well. You can do hollow section and just the length you need that way.

You designed your own cranks and had them 3d printed? Was that expensive?

 

[G-Sport]

You designed your own cranks and had them 3d printed? Was that expensive?

More expensive than the forged cranks but not ewings territory either. Currently paying about 60 cents (US) per gram for Aluminium. With a short crank and good design to make full use of the printing you can save a lot of weight. The ones I did were about 275g for the pair so with shipping just under $200.

 

[KnollyBro]

More expensive than the forged cranks but not ewings territory either. Currently paying about 60 cents (US) per gram for Aluminium. With a short crank and good design to make full use of the printing you can save a lot of weight. The ones I did were about 275g for the pair so with shipping just under $200.

That's very good! So, you designed your own Cranks? What software did you use? Do you have any pics? Where does someone get something 3D printed in aluminum? Are 3D printed parts as strong as cast Cranks? Thanks!

 

[G-Sport]

Designing bike parts is my job. Can't show the ones I did unfortunately, but picture of the test bosses I printed to check the spline fit are below.
I use Solidworks which is kind of the standard in the bike industry but the files I send to the 3d printers (in China, using online upload links) are STL's which most (if not all) CAD software can produce, so there are cheaper/free alternatives.
They claim pretty decent properties for the material but I would/do put a hefty safety margin of error in there, comparing to cast (not forged) material is pretty reasonable.
Because it is 3d printed you can put material exactly where you need it rather than where it would need to be to be manufacturable so you can get good strength at a lower weight. However you do need to consider where any internal cavities can vent the un-used material after printing.
Last lot of printing I had done was using In3dtec, came out pretty decent.
Printing small stuff is generally much more cost effective.
I did these Magura brake dropper perches and they were so light they worked out cheaper than the proper Magura ones with the advantage of putting the lever where I actually wanted it rather than at a really awkward angle.

Also worth remembering that you can't print the pedal threads or the threads for the removal cap at the motor end. Drilling the pedal hole to size and cutting the threads is no problem but the removal cap is a lot trickier. I opted to print some features on the crank to accept an alternative remover instead.