# Rear Hub Axle Flex



## Znugg (Feb 16, 2008)

Hello everyone,

I think this has been an on going problem on our tandem. 

Currently we are using a rear White Industries M16 rear Disc Jockey hub. I got a XTR QR on it. 

We have Magura Julie Disc(7in?) brake in the rear. It only rub when we are cranking up hills. When we are on the flat, there is no rubbing. A local bike shop suggested that we need to beef up that rear axle because is is flexing. Any suggestions? Do you know if I can get a thru axle for the rear with this hub? Or do I need to get a new rear hub?

We are riding: Ventana El Conq.

Thanks,


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## patineto (Oct 28, 2005)

Okay I never bend, break or even flex one to the point of trauma, since I don't have a full suspension tandem.

Then again the lack of serious rear ends is one of the reasons why I'm interested in any tandem currently available.

I can tell you that the difference in between a 135mm QR type and a 135mm x 10MM with a solid trueaxle, is pretty substantial (Giant DH from 2002) in terms of rigidity of the rear triangle









Then again the 165mm x14MM trueaxle of my Nicolai M-pire is so freaking rigid is almost pointless, even for a downhill bike.









But maybe will be just the ticket for the Ultimate Full suspension tandem machine, if the flanges were separated enough to create a very strong, stubborn wheel, plus feature bearing in the center of the hub, to prevent breakage.









I'm sure you can buy rear hubs with 10mm solid axles in 135mm, 150mm but I don't know what other sizes are available.

Oh Ringle's suck, so don't even try. but DT, King and hadley make so awesome stuff.


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## Znugg (Feb 16, 2008)

Thanks-Patineto.


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## patineto (Oct 28, 2005)

Znugg said:


> Thanks-Patineto.


Sorry I don't have a Better picture, but at least in my eyes this is the way a proper rear end on a tandem needs to be like, not as much in the way of the linkage or the pivot point locations but the way the hub is afix to a very rigid swingarm (then again the frame need to be able to take the load provide it by a much more rigid rear end).









Specially if the frame and swingarm are made of aluminum and operated under so many lateral and torsional loads (not to mention the typical upside down rigors of a full suspension bicycle) when ridden hard in the dirt affecting (wearing out and stressing) the linkage mounting points at the seat tube and bottom bracket area and also the hub axle, flanges and cassete interface..


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## TandemNut (Mar 12, 2004)

Hein,
As we discussed, check the suspension pivots on your el Conquistador frame. The torque specs are here: http://ventanausa.com/faq_maintenance.html. Sometimes a new frame may develope 
slop after an initial ride if there is any powder coating residue or other stuff on the facing of the suspension pivot mount.

Also, I'd suggest a heavier steel skewer such as a Kore or other brand. The lighter alloy XTR may be letting the wheel flex within the dropout.

Finally, make sure there's no side play in the rear hub axle itself. I know you recently had the hub serviced and new bearings installed; just make sure they didn't somehow seat themselves more after an initial ride or two and now have some slop in them. Here's a page on WI's website with specific hub instructions:
http://whiteind.com/Tech_Info/INSTRUCTIONS/rear-hub-instructions.htm

Also doesn't hurt to make sure the rotors are properly seated on the hub face, and double check to be sure the rotor mounting bolts are tight.

Hope this helps!


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## Znugg (Feb 16, 2008)

Thanks-Alex.


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## Znugg (Feb 16, 2008)

Here is an update:

Well, I rechecked all the suspension pivots on your el Conquistador frame and it seem to be torque down as what Ventana suggested.

I checked the hub to see if there is any side play, which is also none. I get a little from the spokes flexing, which is normal I think.

I also check the bolts where the rotor and the hub meet. All ok. 

I went on a light test ride today and we still got some rubbing on the climb. 

Next I will try another skewer. 


What kind of setup are you guys running for your rear hub and skewer(axle)? Just wondering if my setup is common or not.


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## Brown_Teeth (Jan 15, 2004)

I'd beef up the spokes, no joke either tighten or go bigger if its flexing.


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## sparrow (Dec 30, 2003)

King rear hub, Heavy Duty steel axle, Fun-bolts, stainless steel rotor body, in 135mm spacing on an El Conquistador de Montanas. Rock solid. Used the same hub, but with a QR conversion and a plain steel Shimano XT rear QR, and it was also rocks solid.


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## Znugg (Feb 16, 2008)

My current wheel setup:
40 hole Sun Mammoth rims,3-cross to White Industries cassette rear hubs, using Sapim 13/14 gauge SS spokes and brass nipples.
I think the rim is pretty strongly built. I will recheck the spokes tension, but I think it is fine.

Yes, my local bike shop mechanic suggested to go with the King hub too. Nice hub, but so price. If only I can get it at a cheaper price.


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## TandemNut (Mar 12, 2004)

That's a White Industries/Sun mammoth rear wheel with Sapim 13/14g spokes and brass nipples. I don't think the wheel is flexing that much in the spokes, and the hub is certainly proven for tandem use. I suspect the issue is somewhere else, unless the spokes just loosened way more than normal. Hein and Susan are not a heavy team, so I doubt that's the case. Until the skewer is changed to something a little beefier, I'd be looking there next.
As I understand it, the rotor is only rubbing while climbing; I'm wondering if there's a connection between the flexing of the rear suspension on the pedal stroke, such as if the caliper mount is not perfectly aligned. 
Hein, did you guys face the disc mounts on the el Conq frame before you transferred the brakes over from the Fandango?


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## Sam Jones (Feb 25, 2005)

Folks, I must be missing something because I don't see how spokes and/or rims have anyting to do with a rotor rubing the brake pad???


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## frisky_zissou (Jun 4, 2006)

The OP was stating that he thinks the axel is flexing under load which is resulting in the rotor moving in the caliper, thus rubbing.

This tandem idea is very interesting. Haver never once rode one the idea of racing on one with some close friends sounds extremely fun. I'll be getting a car soon (just turned 17) so I will be able to make it to more races. A tandem is def. something I need to try out.


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## Znugg (Feb 16, 2008)

Hello everyone, 

I finally got some good news after doing some testing and asking bike professionals for advice. 

I went to the Sea Otter Classic and found a vendor that has a beefy rear wheel with thru axle for me to buy. 
It is a Halo rim and I think it is a Halo hub. The wheel is built with 13/14 gauge SS spokes and brass nipples. 
Man, this wheel is super beefy. It is designed for DH. 

I installed it on our Ventana El Conq and went on about 5 rides and no more rear disc rubbing so far. Knock on wood.  
Yes, no more rear disc rubbing. So all this time the axle was flexing. I think most of the flex came from the QR setup. 
Even using a heavier steel skewer such as a Kore or other brand still caused flexing for us. 

Thank you to the all people that took the time to help us out by giving us suggestions in person, over the phone and on this forum. 
Extra Kudos for Sherwood at Ventana and my friend Andy for going the extra mile to help us out.


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## Hurricane Jeff (Jan 1, 2006)

I use a DT-Swiss FR 36 spoke hub on a Mavic D 819 rim with DT 14g spokes w/brass nipples on our Ventana El Testigo, I have not had only problems with this setup.
I highly recommend getting the burliest hub/ rim that you can find to use on any tandem.


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## MTK (Feb 18, 2004)

*Off topic,*



Hurricane Jeff said:


> I use a DT-Swiss FR 36 spoke hub on a Mavic D 819 rim with DT 14g spokes w/brass nipples on our Ventana El Testigo, I have not had only problems with this setup.
> I highly recommend getting the burliest hub/ rim that you can find to use on any tandem.


Sorry,but I just wanted to know if you are one in the same? I lost contact with you
after you closed the Door's. It's been years since I have spoken with you. I'm still
runnin your post baby. I have 3 of them,and a stem. Peace.

MTK


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## Fleas (Jan 19, 2006)

Sam Jones said:


> Folks, I must be missing something because I don't see how spokes and/or rims have anything to do with a rotor rubbing the brake pad???


You are totally right. You can cut the spokes out of the wheel and the rotor is still in the same place.
The rear triangle is flexing. The addition of the heavier thru axle only goes to add rigidity to the rear triangle by virtue of its method of attachment. An axle does not flex over the 135mm - the dropouts flex, the tubes flex, the pivots slop out on the order of a fraction of a millimeter, but the rotor is only clearing by that much, so that's enough.
This subject of axle flex - IN MY OPINION - is hogwash.
I've heard it over on the 29er forum as well.
If you screwed an axle shaft into the wall and stood on it, it wouldn't flex.
If you supported it over a 135mm span, and two people stood on it, it wouldn't flex.
It is the frame.

-F


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## Hurricane Jeff (Jan 1, 2006)

It is me, Jeff from Hurricane Components, who are you?
I did'nt close up, I sold Hurricane after the birth of our son so I could spend more time with him than working in the shop, at the events, in the office, etc.
I really do miss the business and all of the great people I had met while owning Hurricane, thanks to you all!

Hurricane is still around, but they only produce the Fork Up's and a truck bed/ SUV rack.


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## TandemNut (Mar 12, 2004)

I have to agree. That rear wheel was 40 spokes, Sun Mammoth rim, 13/14g butted dh spokes. The new wheel would appear to be similar in spec. I don't think the wheel was flexing. 
I have not heard of this sort of issue/complaint from el Conquistador owners before. I have to think there might have been some other issue involved. 
We're riding that very wheelset on all of our demo tandems, I alone weigh as much as some teams, and we don't get rear rotor rub.
But then gain, if the rubbing has stopped, then I could be full of it...


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## Znugg (Feb 16, 2008)

Hello Alex,
Here is some close-up pictures of the old wheel as requested.




Again, thank you everyone for your feedback and help. As of this point, I still do not have a clear understanding what is going on, 
but the current Halo rear wheel setup is working great after testing it about 700 miles on it so far.


Cheers,


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## jlib (Apr 22, 2009)

Znugg said:


> ...I went to the Sea Otter Classic and found a vendor that has a beefy rear wheel with thru axle for me to buy. It is a Halo rim and I think it is a Halo hub. The wheel is built with 13/14 gauge SS spokes and brass nipples. Man, this wheel is super beefy. It is designed for DH...


That is exactly what I am looking for! Can I I get your vendor info? Thanks!


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## Znugg (Feb 16, 2008)

jlib,

I got it from: Unreal Cycles 
http://mtb.unrealcycles.com/
I checked on their website and it looks like they do not have the Halo wheel. You might want to give them a call. 
You can also do a google search: Halo Wheel SAS Disc 
You should find some vendors that sell it.

I purchased a CK DH rear wheel with funny bolts about 6 months ago and switched out the Halo and I still get rubbing in the rear disc brake. I switched it back to the Halo wheel setup. So far the Halo setup is the only one that works for me with no rear disc brake rubbing.

The whole thing is still a mystery to me. All the suspension bolts and joints are torque down to Ventana recommendation. If I have time in the future, I might look more into the brakes or other things.


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## rbtcha (Nov 17, 2007)

Hey
So i was just browsing and don't seem to have the problem with rotor rub on the rear. I'm running a Hadley hub laced to a Sun Double Wide 36 hole on the Custom Ventana that I have (same rear as the newer El Conquistador). But I also have Magura Gustov brakes on it which are a floating caliper brake. Dont know if that will help but it seems to work for me

Zipper


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## Znugg (Feb 16, 2008)

Thanks--Zipper


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