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-   -   Reducing dish vs. unsupported axle (http://www.bikeforums.net/tandem-cycling/931230-reducing-dish-vs-unsupported-axle.html)

Bezalel 01-24-14 02:51 AM

Reducing dish vs. unsupported axle
 
My tandem currently has a 135mm OLD rear wheel. While a true tandem wheel is out of my budget, I was thinking around widening a MTB hub to 140 or possibly 145mm.

My question is will this result in a stronger or weaker wheel? There would be less dish in the spokes but there would end up being more axle unsupported on the NDS.

ironhanglider 01-24-14 03:37 AM

Quote:

Originally Posted by Bezalel (Post 16436615)
My tandem currently has a 135mm OLD rear wheel. While a true tandem wheel is out of my budget, I was thinking around widening a MTB hub to 140 or possibly 145mm.

My question is will this result in a stronger or weaker wheel? There would be less dish in the spokes but there would end up being more axle unsupported on the NDS.

Do you mean 145mm or are you planning on widening your frame?

Is there already a problem with your current wheel?

Are you planning on building/rebuilding wheels yourself or do you expect to have to pay for it?

FWIW I think that you are right, if you put a longer axle and spacers into a MTB hub, the wheel would be stronger but you are more likely to bend/break axles. Do you have a supply of suitable axles available?

Otherwise I'd be tempted to keep the frame as it is and use a MTB hub with as many spokes as you can easily find (32 or 36), built into deep section rims (like Velocity B43) this will build a wheel that will be strong enough, but not weight weenie.

Cheers,

Cameron

Bezalel 01-24-14 05:03 AM

Quote:

Originally Posted by ironhanglider (Post 16436636)
Do you mean 145mm or are you planning on widening your frame?

My current wheel is 135mm but the frame itself is about 138mm.

Quote:

Originally Posted by ironhanglider (Post 16436636)
Is there already a problem with your current wheel?

One of my other bikes needs a replacement wheel so I was thinking about giving it my tandem's (MTB) wheel and building a stronger wheel for the tandem.

Quote:

Originally Posted by ironhanglider (Post 16436636)
Are you planning on building/rebuilding wheels yourself or do you expect to have to pay for it?

I'd be building it myself.

fietsbob 01-25-14 12:00 PM

Quote:

My tandem currently has a 135mm OLD rear wheel
Quote:

building a stronger wheel for the tandem.

get a 36 spoke shell Rohloff hub , they are 135, and you can just run a double crank on the stokers BB.

the whole drive train is simpler ..

<[people tour the world on them already, many on tandems too ..

the 36 hole hub-shell an alternative to the 32 hole that has been use successfully
in tandems and touring riders world wide and riding around the world entirely..

The new case was
created to serve tandems and heavy load carriers .. (perfect as a 3 X build. )

inherently stronger wheelbuild, than any cassette hub ..

ironhanglider 01-27-14 05:10 AM

The Rohloff option would certainly be a neat solution, but it doesn't come cheap.

It sounds as if the frame was originally 140 and had been brought in when the smaller OLD wheel was fitted.
Since you sound as if you are both able and prepared to tinker, which opens up a world of possibilities that you would otherwise have to pay through the nose for in the first instance, and secondly others might not be prepared to go 'outside spec' due to liability issues.

It would be tempting to slot a spacer onto the LHS of a MTB hub (assuming rim brakes) and bring it out to 138 - 140. If you have cup & cone hubs you could also likely use the same axle by shuffling it over a couple of mm and having less overlap within the dropout.
If you did this you would gain a bit of strength by having a slightly less dished wheel. As for the axle, it depends on the riders and the way it is ridden. Obviously there is more of a risk with heavier riders. I ride a tandem with a total weight of 220kg and I would certainly give it a go, but I am a thrill seeker. Those with more conservative leanings would be on the lookout for a proper 140mm hub.

Good luck,

Cameron

Bezalel 01-27-14 10:25 PM

The tandem was originally speced by Raleigh for a 135mm wheel but I don't know if that was the intent when the frame was designed. I'll be using a Shimano 36 spoke hub, (Deore or higher) keeping the existing axle if I go to 140 or getting a 158mm axle if I go to 145. (I'm having a hard time finding a 151mm axle and can't figure out why Wheels Manufacturing makes a 158mm axle instead of a 156mm one.)


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