Pole Voima swing arm CRACKED

[Tomska23]

I'm your huckleberry.
To begin with, long before you start thinking about your swingarm, you need to get to work on that crack in your garage floor.

I feel for you Pole owners. You're really getting boned But I'm not surprised that the company is having problems. Their machined frames caught my eye when they came out. Not because I like them, but because it seemed like a goofy idea. Everyone else is hydroforming or making carbon frames in molds. It's an economical and well established process. But Pole wanted to machine each part in a very expensive machine using a time-consuming process. I couldn't figure that one out, but just assumed that they knew more about production than I do, and wrote it off. In retrospect, we can see it's a bad idea.

But regarding your actual question, I'm not 100% certain. Maybe your idea will help mitigate potential failure. But it will be VERY time consuming. If I was in your position, I'd keep a very close eye on the swingarm. If a minute crack starts to form, I'd reinforce it and weld it up. Maybe reinforcing and welding would be a good proactive measure. I'd do that before grinding it down.

Hello! Welding in practice wont work as 7075 is a nonweldable alloy due to its mixture of metals. The problem is also that once the cracking starts it wont help to keep an eye on it. Fatique cracking happens in three steps (dont quote me im not a metallurgist) and the first step happens in such a way that you wont be able to see if its cracked. The visible cracks happen after more fatique and then its too late.

Thanks to plummets picture on the cracked swingarm. Since the cracking indeed in some cases start from the already smooth surface it would suggest that its a defect that wont be removed after sanding. The warranty thing is another story too which i wouldnt put my bets on for the future. Seems like my original plan to reverse engineer the swingarms just like earlier discussed here might be the best solution if this breaks. If mine breaks im open to share any cad/cam files i make, if someone else takes on the mission to use a coordinate measuring device to locate all the pivot points in xyz. Since you’d have to replace both sides, the location of those points would not matter that much. Im quessing a tolerance of +-0.1mm in xy-plane would be acceptable to not make noticeable difference to the kinematics. Prototyping with printed parts and machining + stocks of 7075 would probably cost around 1000€/set. Its an estimate and does not include any time/effort pricing.

Engineering is fun. Lets wait for mine to crack and we can get designing a swingarm. Anyone with marketing skills could market them in social media and even make a small batch of business there. What do you guys think?

 

[Andorranik]

Add me to the broken Swingarm list.....52yo 90kg in Andorra (gnarly single track) 810km from new.....
I frikkin love this bike........ climbs like a Mountain Goat and soaks up the Gnarl like a good un.
Count me in if there is any cnc group purchase I really really want this bike to keep going......in the mean time back to a Trek Rail (will swap the race motor over from the Voima)

 

[tooFATtoRIDE]

What a mess we have gotten ourselves into....

 

[TheSnowShark]

As a future POLE customer, I was very lucky not to have the financial means before ordering..

 

[tooFATtoRIDE]

As a future POLE customer, I was very lucky not to have the financial means before ordering..

Consider yourself lucky.

But I do hope that Pole eventually raises from the ashes like Phoenix...

 

[Suns_PSD]

View attachment 140740
I will be conducting an experiment on my swingarms. It includes sanding down all the surfaces to smooth finish that are prone to cracking due to fatique and or the combination of heavy riding.
There are multiple sources on metallurgy that study the effects of surface finish to fatique strength. The studies would almost always correlate rougher surface finish to worsened fatique strength in alloys (7075 used in pole). Every crevice between the machining lines that are left during roughening with a ball-head mill leave possibilities for fatique microscopic cracking which then starts its journey to form a visible crack in the alloy. Reducing these stress concentration points in this high stress area most likely will reduce the amount of stress concentrations and give a longer fatique life to the alloy. One could argue that removing alloy from the surface would create a smaller section of the profile and thus lead to higher stress. This is not a thing that should be taken into account since the low points between the grooves are already that minimun cross sectional area and removing the high points of the machining marks would make the cross sections even with the low points. When designing the parts in CAD you make a cross section based on the model and the ball-mills end point will follow that profile leaving a minimun of that designed cross sectional area. All the high points are not considered in the CAD models but rather left from the machining process as additional material. More material in this and in many case does not correlate to higher capability to withstand forces but rather make it more vulnerable to cracking.

Enough said. Id like to hear your opinions too before i make anything permanent. Lets argue!

View attachment 140739

My thoughts are that you can't make it worse. But I'd be more inclined to lay up CF sheets over the parts before they break at the weak areas.

GL. I feel for you guys I really do.

 

[Plummet]

My thoughts are that you can't make it worse. But I'd be more inclined to lay up CF sheets over the parts before they break at the weak areas.

GL. I feel for you guys I really do.

There's not enough room between pivot points and stress riser failure point to do anything meaningful with a carbon layup. The stress riser is a design flaw.... no easy way of getting rid of it bar remaking that part without that flaw.

 

[Plummet]

I am considering making some swingarms out of 3D printed titaium. There is also a guy on the pole facebook page looking at CNC'ing some one piece units.

PS My Pole is still going. Just considering my options when/if it fails. Also to make a solution available to other Voima owners who have failed swing arms.

 

[tooFATtoRIDE]

I am considering making some swingarms out of 3D printed titaium. There is also a guy on the pole facebook page looking at CNC'ing some one piece units.

PS My Pole is still going. Just considering my options when/if it fails. Also to make a solution available to other Voima owners who have failed swing arms.

3D printed titanium... that must be $$$

 

[megabobra]

Add me to the broken Swingarm list.....52yo 90kg in Andorra (gnarly single track) 810km from new.....
I frikkin love this bike........ climbs like a Mountain Goat and soaks up the Gnarl like a good un.
Count me in if there is any cnc group purchase I really really want this bike to keep going......in the mean time back to a Trek Rail (will swap the race motor over from the Voima)

View attachment 141598

Just trying to get some context on these cracks, are they all on the underside of the swing sram?

 

[Plummet]

3D printed titanium... that must be $$$

For a one off or small production run it is not cheap but reasonable. The cost tool up for complex cnc machining is likely to cost more unless you know a cnc mate who can absorb some of the set up time.

 

[Darkyhs]

For a one off or small production run it is not cheap but reasonable. The cost tool up for complex cnc machining is likely to cost more unless you know a cnc mate who can absorb some of the set up time.

To be honest, at this moment we do not have anything rather than one guy on facebook that has started working with resin. We all hope Pole will continue to live, but in case it doesnt we will need alternatives. As they have sold quite a bit of bikes. I can only applaud all the people that try out solutions.
To be honest, if I know that it costs me 2/3k to keep the bike going , I would pro-actively get it to ensure my bike to keep pointing down on the hills

 

[megabobra]

So I know there's been several mentions about the inability to weld 7000 series alloys, ruling out a weld fix for these cracks. But I mean, Nicolai's new Saturn 16 is 7020 and it's all welded together. Google says some 7000's are fine to weld while others are not.

Maybe Pole's is fine?

 

[Plummet]

So I know there's been several mentions about the inability to weld 7000 series alloys, ruling out a weld fix for these cracks. But I mean, Nicolai's new Saturn 16 is 7020 and it's all welded together. Google says some 7000's are fine to weld while others are not.

Maybe Pole's is fine?

It's a no go unfortunately. Even if you manage to weld it, welding destroys the heart treatment in that area, the swing arm would need to be normalized and then re-heatreated again, that would in term damage the bonding glue and lead to further failure..... if you managed to weldup the entire bonding successfully them you would still have the same stress riser and failure point which would fail again.......

The answer Is a replacement that doesn't have that weak point.

 

[Tomska23]

It's a no go unfortunately. Even if you manage to weld it, welding destroys the heart treatment in that area, the swing arm would need to be normalized and then re-heatreated again, that would in term damage the bonding glue and lead to further failure..... if you managed to weldup the entire bonding successfully them you would still have the same stress riser and failure point which would fail again.......

The answer Is a replacement that doesn't have that weak point.

I think this is the conclusion we need to accept at this point. Also seems that every single bike will fail prematurely. Has anyone heard any rumours on pole resurrecting?

 

[Andorranik]

Just spoke to BMC in Switzerland to Discuss getting a frame of the SCOR 6080.....very closed minded and not even willing to give me an email address to send a request to...............only "B2B".......great opportunity for them to onboard god knows how many Voima owners as everthing from the voima would swap straight over (minus the shock 250 / 230). they could market it as the "6080 Pole Position" So I have discounted a SCOR from my shortlist.

Edit : Got a good deal on a 6080 GX complete bike from local SCOR dealer.....please see my SCOR 6080 thread to see how it compares to the Voima.

 

[Plummet]

Just spoke to BMC in Switzerland to Discuss getting a frame of the SCOR 6080.....very closed minded and not even willing to give me an email address to send a request to...............only "B2B".......great opportunity for them to onboard god knows how many Voima owners as everthing from the voima would swap straight over (minus the shock 250 / 230). they could market it as the "6080 Pole Position" So I have discounted a SCOR from my shortlist.

You can always buy a complete bike and sell all the parts you don't want.

 

[Plummet]

I think this is the conclusion we need to accept at this point. Also seems that every single bike will fail prematurely. Has anyone heard any rumours on pole resurrecting?

Just some murmerings. It appears there has been some offers for the business. Though, the longer the process takes the less likely a successful outcome......

There has also been some stuff auctioned off in finland like steel frames and the like. I'm not holding my breath.

 

[Tankboy]

Cheapest and quickest way to make new strong swing arms could be either welded Alu or steel. Alu obviously lighter but would need post heat treatment and re-machining. Weight really isn't so important on heavy all ready ebike.

 

[Plummet]

A guy on the pole facebook page had a novel approach to reinforcing the swingarm after cracking.

Worth a try for those with cracked swing arms. What have you got to loose?

 

[Plummet]

Cheapest and quickest way to make new strong swing arms could be either welded Alu or steel. Alu obviously lighter but would need post heat treatment and re-machining. Weight really isn't so important on heavy all ready ebike.

There comes a point where the bike is too heavy. I am close to that point with the my voima now. For me when I cant lift the bike over a fence easily then its too heavy. With a water bottle on the Voima is 26kg. 26.5kg with lights. Its getting real difficult to man handle over some fences. If i added a couple more kg it would just be too much.

So even on heavy e-bikes weight is a problem!..

The problem with welding tubing on the Voima is there is little width for tubing sections left as the swing arm pivot points are WIDE and the linkage system design is in the way of where you would triangulate traditional tubing. It is neither an easy or straight forward solution.

Also welded tubing requires extensive design, testing and jigging. Weld pull and distortion is real and needs to be understood and accounted for during a prototyping process. Unless you are doing it for yourself at no cost of labour the R&D cost has to be amortized into the part cost. A welding tubing option will be more expensive than one piece Cnc or 3d printed parts for low volume solution

 

[megabobra]

So IF Pole does come back to life, who's going to be buying a spare set of replacement swing arms preemptively, even if your frame is looking fine?

 

[Andorranik]

I am currently dismantling my bike as I will transfer all the parts over to the SCOR that should arrive in next few days. the level of machining is truly beautiful. Would pay for a new upgraded swing arm happily just to help out the company as opposed to just bitching for my new one under warranty.

 

[tooFATtoRIDE]

I am currently dismantling my bike as I will transfer all the parts over to the SCOR that should arrive in next few days. the level of machining is truly beautiful. Would pay for a new upgraded swing arm happily just to help out the company as opposed to just bitching for my new one under warranty.

Did you get the frame only or a complete bike?

 

[NickyTee]

So IF Pole does come back to life, who's going to be buying a spare set of replacement swing arms preemptively, even if your frame is looking fine?

My Voima is running first gen swingarm, so I'd definitely buy a spare set, if made available by Pole.

Not riding my Voima much right now, because I'd be gutted if I killed it.

Mostly just riding my Evolink 140 or my Taival

 

[Darkyhs]

I am currently dismantling my bike as I will transfer all the parts over to the SCOR that should arrive in next few days. the level of machining is truly beautiful. Would pay for a new upgraded swing arm happily just to help out the company as opposed to just bitching for my new one under warranty.

For my information, I read somewhere you cannot change the motor angle(or you don't plan to move the motor?). How big is the seat tube diameter? If it is also the same battery as the Pole, it would be a very viable solution for me in case the swing arm goes banana's

 

[Andorranik]

For my information, I read somewhere you cannot change the motor angle(or you don't plan to move the motor?). How big is the seat tube diameter? If it is also the same battery as the Pole, it would be a very viable solution for me in case the swing arm goes banana's

I want to put my CX race motor in the 6080 so for sure I will find out.....don't believe everything you read!!! ......the seat post dimension is unknown until the bike arrives or someone here chips in.
P.S. I did start a SCOR 6080 Thread where I will document the change over from the Voima to the 6080 (they tell me it will be here Friday)

 

[Andorranik]

I want to put my CX race motor in the 6080 so for sure I will find out.....don't believe everything you read!!! ......the seat post dimension is unknown until the bike arrives or someone here chips in.
P.S. I did start a SCOR 6080 Thread where I will document the change over from the Voima to the 6080 (they tell me it will be here Friday)

I am also purchasing a Commencal Meta Power SX and asked about the motor from the tech guys who were very helpful.
The Angle of the motor is only to adjust the pickup for the wheel magnet. If you run a sensor to the rear disk pickup angle is not required. It will be interesting to compare the SX to the Voima and also the SCOR.

 

[Onetime]

So IF Pole does come back to life, who's going to be buying a spare set of replacement swing arms preemptively, even if your frame is looking fine?

I would buy a set.

 

[tooFATtoRIDE]

Same here.