Rear wheel of tandem sliding in dropouts under higher power input.

[Phil W]

Hi,

Does anyone have suggestions on this problem.

A blind friend has 1991 Galaxy (531 tubing I think).  If we put a moderately high level of force on the pedals this translates into pulling the drive side forward in the dropout causing the rear wheel jam on the left side chain stay.  So for any hills or starts I have to put the bike in a very low gear and we sift pedal as we get started. Had to reset the rear wheel six time today. I am thinking that back in 1991 it was still bolt axels and so the clamping force in dropouts was much higher.

Any ideas on how to get the rear wheel axel to stay in place when we are putting more power down ?

[PaulF]

Firstly try giving the dropout and qr a good clean to remove any grease.

Failing that could  a chain tug be modified? I’ve only used them in horizontal dropouts so I don’t know the answer

[psyclist]

I am thinking that back in 1991 it was still bolt axels and so the clamping force in dropouts was much higher.

I might be stating the obvious, but have you tried a bolt axle? That’s what I’ve used on singlespeed bikes without any issues, albeit with somewhat less power than you’d get on the tandem.

[The French Tandem]

Have you tried a new QR lever? As far as I know, slipping QR axles are not a common issue on tandems, even with very strong and heavy teams, so I would suggest that your QR lever is probably worn out.

A

[hubner]

Try an internal cam QR.

Make sure dropouts are parallel.

Make sure the QR is not bottoming out on the hollow axle.

Apparently, QRs can exert more force than solid axles and nuts.

[grams]

I had a similar problem with a second hand bike, and it turned out the cones had shifted off centre along the axle so much that the protruding parts of the axle were longer than the recess in the skewer.

[Phil W]

I am thinking that back in 1991 it was still bolt axels and so the clamping force in dropouts was much higher.

I might be stating the obvious, but have you tried a bolt axle? That’s what I’ve used on singlespeed bikes without any issues, albeit with somewhat less power than you’d get on the tandem.

Not my bike so no.

[Phil W]

Try an internal cam QR.

Make sure dropouts are parallel.

Make sure the QR is not bottoming out on the hollow axle.

Apparently, QRs can exert more force than solid axles and nuts.

Good tips. Will check next time I see him. I also have a spare QR so will take that with me next time I see him.

[Phil W]

Just read this on Sheldon. Interesting that he says not to use these type QR on horizontal dropouts i.e. the ones on Sean's tandem. Think I have a spare internal type QR in my box of spares / delights.

Despite the marketing hype associated with these "boutique" skewers, they are actually considerably inferior in functionality to the traditional type. They are often seen under rather prestigious names, as was the one photographed here. (I Photoshopped the logo off, so as not to pick on one particular brand.)

The exposed cam cannot be kept as clean and well-lubricated as the shielded one can.

In addition, the exposed cam has a larger diameter, (typically 16 mm vs. 7 mm for an enclosed cam) so the friction is acting on a longer moment arm (the radius of the cam.)

The result is that the exposed-cam type provides very much less clamping force for a given amount of hand force on the lever.

Fortunately, the move toward "boutique" skewers happened after the industry had mostly moved to frames with vertical dropouts and forks with "lawyer lips."

The exposed-cam skewers are generally OK for vertical dropouts in back, and for forks with "lawyer lips", but should not be relied on with horizontal dropouts or plain forks.

[mcshroom]

I'm going to go for the QR bottoming out on one side or the other. I had very similar when I tried to slim down a wheel to use in an old steel frame, and discovered what it was after fitting penny washers over the axle and finding they managed to keep the wheel in position.

[Torslanda]

The wheel is obvs not the original so my first question has to be is the axle spaced correctly? The disc hub that's on there was probably originally spaced to 135mm, what was the original frame spacing? 150mm?

I'm not a tandem expert, having very little experience of them but I would imagine that the original was a nutted axle.  If the new wheel isn't the correct dimensions the dropouts won't be parallel. Whatever kind of skewer is securing the wheel it needs to be square to the job.

Personally I would measure the dropout spacing of the frame and make sure the wheel is spaced /dished to be a square fit and use nuts.

[Brucey]

in terms of holding force

Nutted Axle > Security skewer > Internal cam QR > External cam QR

So you have the worst retention in the wheel that needs it most.

The original wheel in that machine (or by that time maybe it was only the super galaxy that had the third brake) would have been a Suzue tandem hub with a nutted axle, set to 140mm (or could have been 144mm, it is a long time since I measured it). The super galaxy (and maybe the galaxy as well) had an Arai hub brake too.

I've used an internal cam QR (Campag Nuovo Record skewers and axles used to be available in the correct length) for tandem TT racing and it was just about secure enough for a good crew, provided you didn't start using a chainring that was too small; smaller chainrings generate higher chain tension and this pulls the wheel over if you have a strong crew. 

I'm pretty sure that an external cam QR would have allowed the wheel to pull over on every start or major effort

You can fit a skinny chain tug (sandwiched between the dropout and the gripping parts on both sides) but this is a mixed blessing; it normally lowers the grip of the QR, and this means that it doesn't so much supplement the grip from the QR as replace it.

Most QR rear hubs with steel axles have an M10 x 1 threading and you can buy (from SJS amongst others) solid (nutted) axles in the correct length and threading  for this job. I'd fit one of those.

They also do an extra long internal cam QR skewer; if the hub is currently spaced to 135mm  this is a bodge for this frameset, but the axle will be about 145mm long and can be respaced to 140mm with extra spacers and so forth. It doesn't make any difference if there is 2mm or 4mm of axle in the dropout, BTW.

hth

cheers

[mzjo]

in terms of holding force

Nutted Axle > Security skewer > Internal cam QR > External cam QR

So you have the worst retention in the wheel that needs it most.

The original wheel in that machine (or by that time maybe it was only the super galaxy that had the third brake) would have been a Suzue tandem hub with a nutted axle, set to 140mm (or could have been 144mm, it is a long time since I measured it). The super galaxy (and maybe the galaxy as well) had an Arai hub brake too.

I've used an internal cam QR (Campag Nuovo Record skewers and axles used to be available in the correct length) for tandem TT racing and it was just about secure enough for a good crew, provided you didn't start using a chainring that was too small; smaller chainrings generate higher chain tension and this pulls the wheel over if you have a strong crew. 

I'm pretty sure that an external cam QR would have allowed the wheel to pull over on every start or major effort

You can fit a skinny chain tug (sandwiched between the dropout and the gripping parts on both sides) but this is a mixed blessing; it normally lowers the grip of the QR, and this means that it doesn't so much supplement the grip from the QR as replace it.

Most QR rear hubs with steel axles have an M10 x 1 threading and you can buy (from SJS amongst others) solid (nutted) axles in the correct length and threading  for this job. I'd fit one of those.

They also do an extra long internal cam QR skewer; if the hub is currently spaced to 135mm  this is a bodge for this frameset, but the axle will be about 145mm long and can be respaced to 140mm with extra spacers and so forth. It doesn't make any difference if there is 2mm or 4mm of axle in the dropout, BTW.

hth

cheers

I can confirm that Galaxy tandems, at least the 1990 model, had a Suzue tandem hub with an Arai drum brake threaded on the lhs (naked the hub is just a big double threaded hub, same thread both sides). I think the later hub had cartridge bearings perhaps; it was not quite the same as the early one that I didn't fit to my tandem. Perhaps 140mm, or perhaps the earlier model was narrower as I fitted mine to a 126mm oln solo frame (without the brake) without much trouble. I think they were also 48 spoke, mine was, and probably both nutted - again mine was, I can't remember for the one in my mate's Galaxy. There must have been an importer's catalogue for these things, possibly Ronkit, to check the details; I bought my hub new as a separate item. The 1990 Galaxy was 7speed freewheel, can't remember if it was Sachs ARIS or Shimano but I think possibly Sachs.

[Brucey]

From  when they (re?) started Dawes tandem production in ~1985, 48H Suzue hubs with cartridge bearings were fitted, with a proper wide rear spacing.

 I still have the very first Super Galaxy Twin they built.

cheers

[Phil W]

I have a spare XT internal cam QR plus I have some penny washers. So I will se how well that cures the problem. We have arranged a test ride with pub stop on Tue. If that does not work then I will look at the proposed options beyond that.

Brucey - by security skewer I presume you mean something beyond an allen key skewer of which I also have a spare. Do you have a link to an example, same for the thread bolt version that may possibly fit?

[Phil W]

Correct the wheels are nor original. Think we braked through the rims about two years ago.

[Brucey]

https://www.sjscycles.co.uk/hub-spares/wheels-manufacturing-cromoly-10-x-1-shimano-thread-rear-axle-solid-nutted-187mm/

should fit most 10x1 threaded hubs and is long enough for 144OLN on a tandem.

By security skewer I mean a long allen bolt type. I am not sure if the extra holding power comes in part from the fact that these are commonly chrome plated, and therefore have very low friction (inside the nut and under the head) so that when greased, you get more tension for a given torque.

cheers