RichinSC1

Curious if the tandem rear axle needs to be solid or will a quick release be strong enough. I have a road tandem riding on very flat land. Thanks

Joint Venture

Hollow QR axles on tandem-rated hubs are plenty strong. Use a good skewer like a DT Swiss. I’ve read that hollow axles are actually more resistant to bending than solid. Makes sense, as the newest standard, thru-axles, are hollow too and they are reportedly the strongest of all.

RichinSC1

Thanks

RichinSC1

Are these ok to use?
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Joint Venture

It doesn’t appear to come in a tandem rear width. The inside dropout faces on your 1990 Duet are spaced at 140mm and QR non-disc road bikes have been spaced at 130mm since 8-speed rear gears came about (MTB and cross bikes were at 135mm before thru axles), so these may be a bit short.

I’ve never seen these in the flesh, but the low price would make me nervous. On a tandem, you really don’t want a QR skewer to break and you need really good clamping force on the rear wheel due to the torque applied by two pedalers! DT Swiss RWS skewers come in a tandem size set up for 145mm inner dropout rear spacing, so they will be long enough for your tandem and they secure as tightly as any I’ve seen since they use a ratchet instead of a cam. This is not a place to skimp!

conspiratemus1

Drilling a hole through a piece of material doesn’t make it stronger or resist bending. It makes it weaker because there is now less material. The bigger the hole, the weaker it gets, obviously. (That’s why termites and carpenter ants are bad news.). Instead, a cylinder resists bending according to its diameter. So if you decide to make a piece with a larger outside diameter to make it stiffer, and it doesn’t have to be any stronger than the original small-diameter solid piece, you will make the piece as a fat hollow tube that weighs the same as the skinny solid rod. There is no magic to the hollowness itself.

The point of through axles on front wheels is to keep the disc brake from ejecting the wheel.

You could make a bicycle frame out of solid steel rods, each rod of a diameter chosen so it used the same mass of steel as the tube it corresponded to. This would be 6.3 mm diameter to have the same mass of steel as a traditional 28.6 mm frame tube 0.7 mm thick. It would weigh the same and be just as strong in tension as a normal frame of hollow tubes but it would too flexible to ride. The rods would soon fail in bending. Tubing is amazing stuff, one of the great achievements of the coal-fired Industrial Revolution.

The canard that hollow QR axles are stronger or stiffer than solid axles of the same diameter has been around for decades. In fact it was the weakness and bendiness of hollow axles that made them break when 7- and 8- speed freewheels came along, and ushered in the modern cassette.

Not trying to pick on you. With the death of Jobst Brandt, someone cantankerous has to step up.

Joint Venture

Makes sense! Supposing the material is the same, of course. I wonder if hollow axles are made of a higher grade steel than solid axles to compensate?

Trakhak

Some, or perhaps most, hollow axles are made of higher-grade steel than most solid axles, but that's because solid axles are for generally used for the least expensive hubs. In any event, the difference in strength between a solid axle and a hollow axle of the same diameter is minimal, as demonstrated by the predominance of hollow axles on better bikes..

RichinSC1

This hollow axle is made from aircraft quality steel. I'm not sure what quality steel solid axles are made from.
https://www.bicyclepartsdirect.com/s...26tpi-x-146mm/

Joint Venture

Might not be long enough for your 140mm rear spacing. Remember, the rear spacing is measured between the inner faces of the dropouts, also known as the rear hub “over locknut dimension” or OLD. 3mm “extra” on each side may not be enough to account for the thickness of the dropouts and provide secure seating of the axle ends in the dropouts. That link indicates it’s for bikes with 135mm rear spacing.

UPDATE: I just checked Tandems East site and Mel has a tandem rear hub from White Industries that is quick release and spaced for 140mm. It’s threaded for a drum and uses cassettes instead of freewheels! Comes in 40 and 48-hole and Mel sells skewers meant for 140mm rear spacing as well. You could run more rear cogs than 6 or 7 that way. It’s worth a phone call to Mel to discuss your options anyway.

Alcanbrad

I’m not sure if the OP was looking for an axle, however, the axle shown from bikepartsdirect is for a cup and cone hub. If your hub has bearing cartridges you would need to find the correct axle for that hub.

In the past I have had several of those (rear hubs only) cup and cone axles break at the junction where the threaded part ends. The QR skewer does a great job of holding everything together without evidence of failure until you remove the wheel.

New2Two

If you are using a quick release hub, do yourself a favor and get the DT Swiss RWS skewers. When using Shimano XT QR skewers we would get disk rubbing after going around corners, the RWS skewers got rid of that. In addition, when you need to reinstall a disk wheel, it is easy to re-center the brake rotor when you tighten the skewer.
Amazon.com : DT Swiss RWS Tandem Steel 145mm with Aluminum Lever : Sports & Outdoors

Rick

Purchase quality skewers and make sure the fork and rear stays are parallel. I have bent solid axles on a tandem but never bent or snapped a hollow axle. This is because I replaced the cheap wheel set that came on my 1990 Burley Bongo with Phil Wood tandem hubs and Campi SS Skewers. The convoluted rewrite of the laws of physics for Skewers on disk brake bicycles has more to do with manufactures cheapening the parts to the point that they became dangerous. Skewers/Quick Releases have obviously been a mystery to many people.

Leisesturm

What the o.p. is not being told so far in this thread is that solid and q/r (hollow) axles are not interchangeable in the same wheel. The entire hub/wheel assembly would need to be replaced. It does not appear that the o.p. purchased a frameset. They have a complete bike with existing wheels and tires. What are they? We should know that to be able to advise them intelligently. In any case, solid axles are NOT usually stronger than q/r skewers. Usually the opposite. Mainly because of the price point and performance expectations of bikes that use solid axles. IF q/r isn't good enough, for whatever reason, then anything stronger would need to be one of the newer standards coming out i.e. Boost. Taking advantage of that would mean a new tandem, since the frame and fork dropouts are unique to the newer axle standards coming on the market. TL;DR: I'd be very surprised that anyone needs to go away from the q/r standard. One of our tandems pulls a BOB Yak single wheel trailer and they sell skewers in tandem spacing for it. If q/r is good enough for a tandem plus team plus loaded trailer its up to the job of an unloaded tandem.

longpete

I never broke a front quick release. I did brake one steelaxle in a xt rear 8 speedhub long ago. I did break a rear campa qr.
So except for front qr and axle, tsems are the only thing i did not break in my career. For an offoad tandem I don't trust rear
12 mm alu hollow axles even with short threads.

Philly Tandem

As a data point, our Santana triplet has a QR rear axle (160mm spaced) and it's held up fine for 10+ years, even with touring loads when the bike, passengers, and gear are likely pushing 500# total rolling weight.

Alcanbrad

This video from Peak Torque dropped yesterday comparing stiffness between QR and thru axle set ups:


It's an interesting watch. The QR skewer and thru axle are only providing clamping force and are not part of the load path between rider and earth. Single, double, triple, ..., it doesn't matter. Another take away I took is that with the size of the levers, it's difficult to achieve the possible claiming force a QR is capable of so there is little chance of a QR failing. This is somewhat supported by New2Two's experience with one set of skewers over the other.

Bottom line to me is that any skewer is fine just insure you are clamped good and tight. Using a brand name skewer would add to yours, and my, piece of mind.

RichinSC1

Nice bit of information there. Thanks.

Alcanbrad

Peak Torque just dropped a follow-on deep dive where he actually measures the clamping force of different QR's. (He has me now rethinking having a carbon fork on a tandem.)

Chris_W

Quick release skewers do a fine job. I only use skewers with internal cams because external cam models may provide significantly less clamping force - there's a reason why Shimano and several other respected brands only make internal cam models. See the photo at the top of this page to show the difference and an internet search should bring up more discussion on this topic that all reaches the same conclusion: internal cams are far better. https://www.bicycling.com/bikes-gear...hat-wont-fail/