Thorn Cycles Forum

Community => Rohloff Internal Hub Gears => Topic started by: MilitantGraham on April 26, 2009, 08:13:13 PM

Title: Spokes, nipples, eyelets and rims.
Post by: MilitantGraham on April 26, 2009, 08:13:13 PM

I've got a DT Swiss XR4.1d rim and I've noticed after breaking a few spokes that the nipples sit square in the rim so that the larger diameter of a Rohloff hub causes the spokes to bend as they enter the nipple.

Like this...

(http://farm4.static.flickr.com/3359/3474215782_689f14c24b_b.jpg)

The black spoke, centre right, is brand new. Look at the angle between the spoke and nipple. That has got to be stressing the spoke.
I've got a Mavic 717 on my other bike and that's got a similar problem, but not as bad.
Is there a MTB rim, preferably something a little bit stronger & wider as well, with a more ball & socket shape to the eyelets that will allow the nipples to self centre and line up with the spokes ?

Title: Re: Spokes, nipples, eyelets and rims.
Post by: julk on April 26, 2009, 09:02:25 PM

Probably best to speak to SJS to see what is available.
Browsing their site I found this rim (http://www.sjscycles.co.uk/product-Rigida-Rigida-Andra-30-Tungsten-Carbide-26-Inch--559-ATB-Alloy-Rim-32-Hole-Rohloff-Drilling--Black-13269.htm) which has drillings optimised (angled) for a rohloff hub.

Title: Re: Spokes, nipples, eyelets and rims.
Post by: stutho on April 27, 2009, 12:01:17 AM

MilitantGraham,

It is possible to slightly bend the exit holes on the rim.  I have 717 rims on both my wife's and my own bike.  On both I have slightly cold formed the exit holes on the rims.  I haven't had a spoke break yet.  (Take it easy if you decide to try this, it will invalidate your warranty straight away) 

Title: Re: Spokes, nipples, eyelets and rims.
Post by: MilitantGraham on April 27, 2009, 07:54:09 PM

That Rigida rim looks to be what I am after, except that is for rim brakes. I would be paying a lot of money for a tungsten carbide coating I don't need.

I found this in Thorn's Living with a Rohloff article, it's not just me then...

Quote

Unfortunately we had several cases of
spoke breakage on the tandems until we discovered the cause…incompatible
rims! The flanges of the Rohloff hub are so large that, with most rims, the
spokes tend to bend as they leave the nipple, eventually this causes them to
break at the nipple…a type of failure which was unheard of…until it
happened! We solved the problem at source...we now have rims drilled so
that the spokes leave the rim in a perfectly straight line, since doing this, no
more tandems have had broken spokes.

I did wonder about trying to kink the rim at every spoke hole. Maybe next time one breaks, I'll try it. I've been thinking about going for a stronger rim on the back anyway, so if I wreck this one, it's not such a big loss.

Rohloff push the advantage of a wider hub giving more even spoke tension, but they don't mention the larger diameter offsetting that advantage.
There's several frame makers making Rohloff specific frames, it's a shame there aren't more rim manufacturers doing the same.
I guess it's a case of supply and demand. there's probably not that many 100kg cyclists doing stuff likethis on a Rohloff.  :D

(http://farm4.static.flickr.com/3508/3456766580_e5cbf58669.jpg)

Title: Re: Spokes, nipples, eyelets and rims.
Post by: Dave Whittle Thorn Workshop on April 27, 2009, 09:21:05 PM

If your careful you can bend the eyelets by inserting a steel rod into them and twisting to the correct angle, we do this on these rims when built for Thorn bikes

Title: Re: Spokes, nipples, eyelets and rims.
Post by: LWaB on April 28, 2009, 10:20:19 AM

I though it was standard practice for good wheelbuilders to cold-set the spoke at the base of the nipple to allow both the nipple to match the rim drilling and the spoke to have a good straight line.  No problems with any of the wheels I've built in this manner all the way down to 16" rims, albeit with a SA 8 speed hub.

Title: Re: Spokes, nipples, eyelets and rims.
Post by: MilitantGraham on April 28, 2009, 05:07:50 PM

Thanks for the replies everyone. That's three people now have said tweaking the rim is the way to do it, so that's what I'll do.

Title: Re: Spokes, nipples, eyelets and rims.
Post by: MilitantGraham on May 25, 2009, 06:38:53 PM

Since my last reply I have broken three more spokes.
I found a Torx key, I think it was a T20 or T25, was the best thing to use.
It was a tight fit through the nipple and being high tensile it didn't bend when I leant on it.
Those three spokes look a lot better than the others now. I ought to dismantle the wheel and do them all as preventive maintenance, but I'll probably wait until they break and do them one or two at a time.

Title: Re: Spokes, nipples, eyelets and rims.
Post by: bike_the_planet on October 11, 2009, 02:47:38 AM

Quote from: MilitantGraham on April 26, 2009, 08:13:13 PM

I've got a DT Swiss XR4.1d rim and I've noticed after breaking a few spokes that the nipples sit square in the rim so that the larger diameter of a Rohloff hub causes the spokes to bend as they enter the nipple.

I have just experienced the very same problem but with Alex DM18 rims. I have just gone through 3 spokes in the last 100kms and am becoming adept at quick spoke changes on the side of the road!!!

Yes, the larger diameter of the Rohloff hub, along with the smaller 559 mm 26" wheel diameter results in a very acute angle when the spoke exits the nipple.

Some rims have the spoke holes drilled in such a way that they are almost in-line rather than right/left/right/left. This also results in more stress than others.

I suspect too that the spokes breaking are the ones that exit the hub from the outside of the flange rather than those exiting from the inside surface - is that right?

One other option that hasn't been mentioned is buying shorther spokes and relacing the wheel using a 1 x pattern rather than the usual 2 x pattern. I suspect that it MAY be possible to have all the spokes exiting the flange from the inside face using 1 x.

Has anyone done this?

Finally, a useful innovation I have found, is replacing rim tape with little plastic spoke hole plugs. As well as rsulting in marginally less rotating mass at the wheel rim it means spokes can be replaced speedily by the side of the road!

Cheers from the arse-end of the earth...

Tony

Title: Re: Spokes, nipples, eyelets and rims.
Post by: Andre Jute on October 11, 2009, 06:24:06 PM

Quote from: MilitantGraham on April 26, 2009, 08:13:13 PM

I've got a DT Swiss XR4.1d rim and I've noticed after breaking a few spokes that the nipples sit square in the rim so that the larger diameter of a Rohloff hub causes the spokes to bend as they enter the nipple.
Like this...
(http://farm4.static.flickr.com/3359/3474215782_689f14c24b_b.jpg)
.....snip.......
Is there a MTB rim, preferably something a little bit stronger & wider as well, with a more ball & socket shape to the eyelets that will allow the nipples to self centre and line up with the spokes ?

You may want to look into the Exal XL25 rim from Belgium and the Rohloff specific spokes from Sapim, also of Belgium.  Both were designed for and in consultation with Utopia, the first manufacturer to specify Rohloff hubs, specifically to solve this and other problems peculiar to the Rohloff hub (and wide tyres), and are made for Utopia but sold to everyone who wants them. The Exal XL25 rim is 25mm across the beads, 31mm outside. Mine are 622 but I know they make a 559 as well.

Right at the end of this link there is a huge photo of a Rohloff/Sapim/Exal XL25 wheel which shows the spoke entry to the rim is straight:
 http://www.audio-talk.co.uk/fiultra/Andre%20Jute's%20Utopia%20Kranich.pdf

Whether these parts, very likely designed for touring rather than stunts with clear skies showing under both wheels, will be suitable for your use is something beyond my ken. I've been in the air at high speed a few times over potholes and so on in the hilly lanes and farm tracks I ride, but that's involuntary; all up my bike and I in day trip trim weigh over an eighth of a ton, and there was no instantly visible damage from these excursions, though I can't say I felt the need for more than a cursory inspection on arriving home; I ride on 60mm Big Apple Liteskins with the extra light Schwalbe Type 19A tubes at low pressures of around 1.8-2.0 bar, so there's quite a bit of cushion for the thump. Any experienced cyclist just knows when wheels have integrity; of course, the magic of a wheel lies in the build quality rather than being the sum of even good special-purpose components.

Hobbes

Title: Re: Spokes, nipples, eyelets and rims.
Post by: bike_the_planet on October 12, 2009, 09:30:58 AM

Quote from: bike_the_planet on October 11, 2009, 02:47:38 AM

One other option that hasn't been mentioned is buying shorther spokes and relacing the wheel using a 1 x pattern rather than the usual 2 x pattern. I suspect that it MAY be possible to have all the spokes exiting the flange from the inside face using 1 x.

Has anyone done this?

Answering my own question here...

Maria from Rohloff Australia has just referred me to the Mounting section (page 55) of the installation
handbook where it says:

All rims larger than 24" in diameter must be laced in a two cross pattern. All
24" and smaller sized wheels must be laced up in a one cross pattern

(Underlines Rohloff's)

So, it appears that one is not allow to build a wheel using a 1 cross lacing for 559mm or 622mm diameter rims - only the smaller 24" rims

Hmmmm...