I was actually wrong in my statement about the torque . And you were right when you wrote that adding a washer would increase the spring preload. The sketch below shows that bolt 373 is actually torqued against axle 340 end. So the cupped spring preload is purely dependant on distance X (spring built-in length).
I think I now have an explanation for the angular movement of the wheel on my bike: the sharp edges of cupped spring 367 eat the surface of the bottom tube and of washer 364 away (as can be seen here), which increases the cupped spring built-in length. These springs are very stiff, which means that a small variation of their built-in length greatly affects their preload.
I have not checked the dimensions of the cupped spring 367, buit I think they are close to these ones: inner diameter: 12.2mm, outer diameter: 28 mm, thickness: 1.25mm, total height: 2.1mm
So, the wear/deformation that can be stated on both bottom tube and washer 364 will make the preload of the cupped spring drop sensibly.
Looking now to the exploded view of the Strida in the manual, you can see a washer 363 between cupped spring 367 and the bottom tube. According to me, this is a flat washer that prevents the wear of the tube and also increases the preload of the spring. I wonder why they have removed it.
I get mad when I see that such cheap parts and poor design can affect the functioning of this otherwise nice bike.
This poor design has following consequences:
Irreversible damage of the aluminium bottom tube.
Clicking noise
Angular movement of the rear axle + wheel : this can trigger the belt to jump on the flanges of the freewheel and definitively damage the belt.
Bad guidance of the rear wheel: it accelerates the wear of the rear tire and causes bike instability.
I sincerely hope that these problems have been solved on the EVO3, as its high price should go together with a high quality level.
thank you so much for research, explanation and the excellent drawing!
Your conclusions are indeed coherent and comprehensible and they also explain the different part numbers of the exploded drawing.
(I was totally wrong to think that there could be two cup springs in that place - as stated erroneously in the post here)
This is anyway a highly important discovery - which should be definitely reported to Ming - and it should be investigated why the washer is missing.
For the cup spring:
Recently weāve reordered a few springs, therefore it was easy to measure the real dimensions of 5 unused original springs;
inner diameter 12,3 mm, outer diameter 23 mm, thickness 1,7 mm, total height 2,9 mm
So - due to more thickness - the force of the original cup springs might be much higher than the amounts of the example from the catalogueā¦
(Interesting detail at the āGroup2; 1,25 up toā¦ā - radiused edges - aha!!)
According to Bill there are only two āwashersā below the rear wheel bolt of the EVOā¦
Last week arrived finally a few EVOs Vienna, Iāll check their rear bolts asap.
Anyway we should tell Ming our opinion about the cup spring!
Honestly, I donāt have much hope, but maybe Ming cycle has learned meanwhile to respect and follow the advice of experienced customers.
[i]I want to beg here also for assistance of technically versed Strida users and dealers!
Ask the Ming cycle technical support about the frame damage, clicking noises, movement of the rear wheel and the missing washer 363 of your Strida.[/i] contact@strida.com
Please report here in the forum if your Strida does have the big washer 363,
I would really like to know if the washer was mounted on older versionsā¦
So the cupped spring of the Strida does not have standard dimensions, this is really strange. It is maybe made according to Chinese standards
Coming back to the contact surfaces of the cupped spring, here is what you can find on the same website as the one of the catalogue:
I wonder also why washer 364 has a stange shape when used. Is it a flat washer when new or is it also a kind of cupped spring? In the first option, it looks like the steel is much too soft for the loads it has to standā¦
āagreeā is not the fully correct expression, it was more like an enlightenmentā¦
Unfortunately Iām really busy at the moment - the heating equipment in one half of my apartment is out of order and itās getting cold here - therefore just a short interim report:
Should be possible to find out, but will take some timeā¦
For the catalogue citation:
Thanks again, didnāt see that!
Hmmm, if we would now simply put hardened steel washers above and below the belleville (cup) spring then would the spring load raiseā¦
ā¦maybe too much for the bolt 373?
What do you think?
Today I could take a quick look at three original brandnew Stridas, EVO, SX and LT:
All of them equipped with the new EU-conform frame, the EVO was taken out from the original box.
Guess what?
NONE of the three was equipped with more than TWO āwashersā below the bolt 373
(At the weekend it will be time to check two more EVOs and look at the washer 364.)
Btw, could you please tell us your meaning to this post?
Yes, that is a solution I was thinking about. If you want to keep the same preload, then you have to put a small washer of the same thickness as all the hardened washers you are adding, between bolt 373 and axle 340. Then the spring built-in length will not change. You just have to make sure that bolt 373 is screwed far enough into axle 340. If it is too short, use a longer one.
I thought washer 364 was centered on axle 340, but it is actually clamped between nut 373 and axle 340. So if you add a washer under the cup spring you need to add another washer 364 but of the same thickness to keep the same spring preload.
In my case, I want a higher preload, so I will not add an extra washer 364.
Calm down, most of us will not have realized that
The drawing is still very good, I was quite unsure about this detail and therefore I wanted to disassemble a few bolts at the weekend.
Seems that we need in sum three washers to reach the target of a fully functional rear jointā¦
Iām also quite unsure how to proceed with this post because it will belong to several known issues of the rear Strida region. To merge the posts is not that good, I thinkā¦maybe pin this post and edit with links to the other posted problemsā¦
Well the proposed solution is less simple than I thought: the distance āXā is only 2mm. The cup spring thickness is 1.7mm, so it can only be compressed by another 0.3mm before being completely flat. It is not advised to push a cup spring until it is flat as the stresses in the spring become too high.
Adding a washer under the cup spring is therefore not advised, if the washer is about 2 mm thick (like the stainless steel one I found in a DIY shop), the cup spring will not be centered anymore and bolt 373 will not be screwed against axle 340.
Overtightening the bolt will damage the cup spring.
Adding a third washer between axle 340 and washer 364 is not ideal because it will not center perfectly and the inner edge of cup spring 367 will not be well guided.
On my bike, I replaced the soft steel washer 364 by a stainless steel one, which seems to be a much harder material. The original washer was quite deformed/worn out, and my first impression today is that the rear wheel swing movement has been reduced by almost 50% by bringing the preload of the cup spring almost back to its inital value.
Had no chance to examine more Evos, sorry for the delay
But Iāve found a good pic of a 3.0 Stridaās rear area- there is an additional washer below the cup spring!
For this pic Iād like to get the permission to use it from [size=150]florian[/size] - are you still here?
Please look at your mailboxā¦
Yes, perhaps not idealā¦but if the thickness of the third washer is below that of the cup spring and the outer diameter very close to that of the axle it should work, I believe.
The third washer should fit inside of the cupspring; imaginable as some kind of axle elongation - shown in red color below.
(Iām here also thinking about a method for easy retrofit - a longer axle, like mentioned by Xentrax here, would be the better solution, but it would also need much more effort for exchange.)
Hope you donāt mind that Iāve used your image for illustration:
I agree with your ā3 washersā solution. However, for a retrofitting solution, the difficulty will be to find standard stainless steel washers with the proper dimensions (diameters and thickness).
You can of course order custom washers made by laser cutting or etching but it could be quite expensive, especially if you have to buy the raw material in large quantity
Well, the drawing was āenhancedāā¦
(Just amazing that the recessed (!) snubber bolt 386 with its nut (!) 387 was not updatedā¦)
For approval are here a few pics of a brandnew Strida EVOās rear joint parts - exactly like the newer drawing - the cup spring (now 367-3) and the washer 364, there is no third āwasherā.
Red arrow: Inner edge mark of the cup spring in the brushed aluminium surface of the frame.
Green arrow: Border of the silver paint, obviously was this area masked before the painting process.
The washer 364 is already deformed, outer edge marks of the cup spring are visible (red arrow).
Below, - sorry to use your pics without permission, florian - the rear area of a 3.0 Strida:
There ARE three washers!!
Could any 3.0 Strida owner please supply more info about dimensions and material of the āmissingā washer 363?
My rear wheel developed some wiggle room last year. I took it out to ride last Saturday, after being stored since December, and the frame broke while riding. Iāve emailed photos to the admin to have them posted. I think the Strida is unreliable after being ridden for many years.
Iām indeed sorry to hear that.
Broken frames are a very special issue I believeā¦
Would you mind to send me the pics too?
Iām quite unsure if Garry has enough time to post themā¦
A There seems to be a tolerance stack buildup due to:
Torque on how axle is screwed into rear forged joint
Thickness of rear forged joint
Surface texture of rear forged joint
Finishing of of rear forged joint
Thickness and wear of Large dia Nylon washer
Thickness of Bottom tube (and its nylon insert/end cap)
Surface texture of Bottom tube
Finishing of of Bottom tube
Axle length tolerance
Spring washer biting into rear tube ā¦ or ā¦ Thickness and wear of any thin washer under Spring washer
Spring washer, thicknessā
Spring washer Hardness
Spring washer edge sharpness
Spring washer surface finish
Spring washer consistency - (taiwan supplier ??)
Lubrication (clear grease).
Small washer Thickness/quality/surface finish
M8 Bolt torque & Thread lock condition.
B The part(s) that takes up all this tolerance stack buildup, and keeps the best combination of folding stiffness vs Joint stiffness/no play is the [b]spring washer/b. This/These should fit between the bottom tube and the āsmall washerā.
The small washer should be torqued up and ālocked solidā by the M8 Bolt, on the end of the axle. Such that the Bottom tube rotates.
The spring washer should rotate with the bottom tube (as its larger diameter, left sloping, bottom end of the cone has more friction than the smaller diameter ātop end of the coneā ā¦ which in turn runs against the harder, more wear resistant (and lubricated) underside of the small washerā¦
thanks for your message - after a long while; Iām happy that youāre still here
Teaching us is very nice indeed, just we did already know several of the mentioned facts and of course weāve read all informations available.
But it seems that Ming cycle didnāt read itā¦
Good to know how it should be, but in reality (at least on Strida EVO and 5.0) is the small washer definitely softer than the cup spring.
I have a Strida SX bought from Velorution, London UK in 2013. Itās been my daily commuting bike (5km, so not far). I started experiencing problems with the belt about a year ago - twisting there times. Velorution replaced the belts and then recently the flywheel and the belt, because they were worn. But now the bike appear to have sideways movement in the rear wheel as quoted in this thread - enough that it caused me to stop the bike whilst riding, fearing that the rear wheel had worked loose. In examining the rear washer (364) inside the bolt, it appears totally deformed. I donāt know the state of the cup-spring (367-3) because I have always left the repairs to Velorution as they are authorised Strida mechanics. I will try and post photos now. Has anyone come up with a fix for this yet? Iāve asked Velorution to order new 364 & 367-3 parts to see if I can at least get back to square one.
Iām 1.89m tall and 87kg so put a fair amount of power through the bike, but not close to the 100kg maximum. I expect mechanical parts to wear. Iāve actually upgraded to the Strida alloy chain set because the flexing in the plastic one worried me, but I had belt issues before this upgrade.
Every time I have taken the bike into Velorution, I get āOh weāve never seen that beforeā which doesnāt fill me with confidence. It looks like a simple fix thoughā¦if as you say the bottom hole has not become oval.
Iām not optimistic, being two years old that it wonāt be oval. Iāll have a look this weekend. Whats the solution then - drill out the hole and fit a sleeve on the axle? Or a new bottom tube?
thank you for the feedback
Yes; there are still companies which are interested to sell - but not support
Hmmmā¦hard to tell; it will be oval; but how much?
If it is much deformed will be a new tube the easier way, they are not that expensive as one might think (accidentally depending on distributor).
I believe the bottom tube, once worn, could be saved just one way:
Replacing of part 100-07 (plastic tube insert) by Aluminium, equipped with needle bearing.
One, two securing bolts of the perhaps also elongated insert across the tube in 90Ā° alignment to the axle. Creating of a fine adjustable pretension mechanism (= friction between bottom and seat tube) would complete a durable rear joint.
Maybe you want to help me forcing Ming for realization?
Perhaps youāre just too pessimistic and the tube hole is fine.
Took off the rear bolt to assess the state of the cup-spring and washer, plus the damage to the bottom part of the frame from the cup-spring.
Washer is totally deformed - you can clearly see the shape of the bolt imprinted into it.
Sideways view shows the deformation further:
Cup-spring has eaten into the frame:
I didnāt want to take the bike apart further, so hard to judge how ovalised the bottom hole might be. Both your fix Chris, and the Canadian option which Bill emailed me about seem like the way to go. Can I order one of your kits Chris please? Thanks Alistair