Tubus Tara different?

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531colin
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Re: Tubus Tara different?

Post by 531colin »

download/file.php?id=99826&mode=view (sorry, don't know how to get Colin 54's picture here!)

I would have a go at repairing that with silver solder, if it was mine.
viewtopic.php?t=49335&start=15....Silverflo 40 will bridge about a 1mm gap, you could also put a "patch" on the outside

Thanks Jonathan!
Last edited by 531colin on 6 Feb 2023, 5:53pm, edited 1 time in total.
Jdsk
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Re: Tubus Tara different?

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531colin
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Re: Tubus Tara different?

Post by 531colin »

pwa wrote: 6 Feb 2023, 4:17pm Surely the way to narrow a Tara would be to simply sit on the main (forward) U bend, to put it crudely. No welds anywhere near there, and the amount of extra bend would be quite small. The question is, how to isolate the bending to the U itself.
The danger with just pushing the dropout ends of the "U" piece together is its likely to crack or kink at the drilling(s). (Somebody said the drillings also have a tube or boss welded ?)
....this is basically what has happened to Colin 54's rear rack.

I think Colin could have bent his successfully "mid-leg" by placing a bit of wood between the legs below the welds, but to bend the "U" will require force above the drillings, which is trickier.

E bay has plenty of benders for 10mm tube, cheap enough to make hiring one unnecessary. They are of course designed for plumbing, ie copper tube, not for Tubus' thin wall steel tube, which, as we see, can crack!
slowster
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Re: Tubus Tara different?

Post by slowster »

531colin wrote: 6 Feb 2023, 5:53pm to bend the "U" will require force above the drillings, which is trickier.
The current Tara racks also have a drilling/welded boss at the apex of the bend to mount a front light. Moreover, bending the U bar so that the horizontal strut mounting points were closer, would also bring the drop out mounting plates closer by around twice as much, as well as making them no longer parallel and thus putting them/their welds under stress when fitted (unless additional bends below the horizontal strut mounting points are made on each side to compensate).

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531colin
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Re: Tubus Tara different?

Post by 531colin »

Non-starter, then!

Either set the rail to "U" piece joint, or bend the rails with a bender..correct the slot mount to the fork as well.
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Re: Tubus Tara different?

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531colin wrote: 6 Feb 2023, 6:21pm Non-starter, then!

Either set the rail to "U" piece joint, or bend the rails with a bender..correct the slot mount to the fork as well.
What do you think of filing the faces of the cylindrical bosses to alter the angle at which the horizontal struts rest against them?

Since the OP has the stainless version of the Tara, there would be not be the concern about removing the paint from the cro-mo version and needing to re-paint after filing to prevent rust
cycle tramp
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Re: Tubus Tara different?

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....er, at this point I'm outta this thread.....

The Tara tubus isn't cheap and should be a quality product and fit within the manufacturers limits (in this case not needing a spacer longer than 8 mm).. if it doesn't then, personally speaking rather than attempt a repair I'd swap it for a front rack which does fit either from Tubus or another manufacturer...

.one thing is probably certain bend, file or attempt to make it fit will mean you won't be able to get an exchange or your money back.
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531colin
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Re: Tubus Tara different?

Post by 531colin »

cycle tramp wrote: 6 Feb 2023, 6:57pm ....er, at this point I'm outta this thread.....

The Tara tubus isn't cheap and should be a quality product and fit within the manufacturers limits (in this case not needing a spacer longer than 8 mm).. if it doesn't then, personally speaking rather than attempt a repair I'd swap it for a front rack which does fit either from Tubus or another manufacturer...

.one thing is probably certain bend, file or attempt to make it fit will mean you won't be able to get an exchange or your money back.
Absolutely agree, it should be "fit for purpose" straight out of the box.....and so should everything else,even "non-premium" products.

..........but if it isn't then you are back looking for something else which works ... anybody?
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531colin
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Re: Tubus Tara different?

Post by 531colin »

slowster wrote: 6 Feb 2023, 6:38pm
531colin wrote: 6 Feb 2023, 6:21pm Non-starter, then!

Either set the rail to "U" piece joint, or bend the rails with a bender..correct the slot mount to the fork as well.
What do you think of filing the faces of the cylindrical bosses to alter the angle at which the horizontal struts rest against them?

Since the OP has the stainless version of the Tara, there would be not be the concern about removing the paint from the cro-mo version and needing to re-paint after filing to prevent rust
I haven't studied one, but filing where the 2 parts join is a good way of getting them to join at a different angle. Even silver solder a washer on top and grind/file that to shape, but that requires more tools etc.
Probably still need to bend the bolts?
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Re: Tubus Tara different?

Post by slowster »

531colin wrote: 6 Feb 2023, 7:44pm I haven't studied one, but filing where the 2 parts join is a good way of getting them to join at a different angle. Even silver solder a washer on top and grind/file that to shape, but that requires more tools etc.
Probably still need to bend the bolts?
Internal diameter of the cylindrical bosses is 6mm, which I think would give enough wiggle room that the M5 bolts might well not need to be bent.

That said, the resulting amount of slop/play of the bolts in the holes strikes me as undesirable - presumably even with the rack fitting perfectly to the fork, the rack is likely to move around under heavy loads/vibration despite the bolts being properly tightened. (Possibly another argument for the design to incorporate spherical washers.)
531colin wrote: 6 Feb 2023, 7:36pm ........but if it isn't then you are back looking for something else which works ... anybody?
I think in some cases rather than a low rider rack, a traditional front rack might be a better choice (if a suitable one can be found). The big benefit of low rider front racks is that they allow the weight to get closer to the steering axis, and that has encouraged people to carry more weight in front panniers, and I think it is questionable whether a low rider rack which is bolted together, and all the bolts of which are potentially stressed/load bearing, is really suitable. The rigid low rider racks without a U bar seem to me to be an even more flawed design, given the lack of bracing.

Many people might be better served by a traditional full height front rack and smaller/lighter front panniers than standard Ortlieb/Carradice models, with less/lighter/more compact kit in them. If memory serves, the Karrimor front panniers in the image below had a small capacity and were joined by fabric which rested on the top of the rack, i.e. no top rail or top hooks, which if done well/strong enough might be better than a rigid hook mounting system for off-road and rough-stuff touring. A lot of modern kit, especially for camping, is now much lighter and more compact, so is it still necessary to get the weight so close to the steering axis?

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531colin
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Re: Tubus Tara different?

Post by 531colin »

They were also higher than the heather, mostly.
cycle tramp
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Re: Tubus Tara different?

Post by cycle tramp »

531colin wrote: 6 Feb 2023, 7:36pm
cycle tramp wrote: 6 Feb 2023, 6:57pm ....er, at this point I'm outta this thread.....

.one thing is probably certain bend, file or attempt to make it fit will mean you won't be able to get an exchange or your money back.
Absolutely agree, it should be "fit for purpose" straight out of the box.....and so should everything else,even "non-premium" products.

..........but if it isn't then you are back looking for something else which works ... anybody?
Personally I'd contact tubus again, let the know the situation and ask to swap for a tara which was built to spec....
..there's a risk that if you attempt to cold set the hoop or u-bend it's going to crack around the wielded light mount, and if you attempt to bend the horizontal arms it could prove difficult to mount and dismount the panniers.
Short of making two metal link plates (which have a slight in the middle) and attaching the arms to the link plates and then the hoop to the other end of thr link plates I don't have an answer, and I don't think link plates are great because they'll compromise the rigidity of the rack and look terrible.
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gregoryoftours
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Re: Tubus Tara different?

Post by gregoryoftours »

cycle tramp wrote: 6 Feb 2023, 10:30pm
531colin wrote: 6 Feb 2023, 7:36pm
cycle tramp wrote: 6 Feb 2023, 6:57pm ....er, at this point I'm outta this thread.....

.one thing is probably certain bend, file or attempt to make it fit will mean you won't be able to get an exchange or your money back.
Absolutely agree, it should be "fit for purpose" straight out of the box.....and so should everything else,even "non-premium" products.

..........but if it isn't then you are back looking for something else which works ... anybody?
Personally I'd contact tubus again, let the know the situation and ask to swap for a tara which was built to spec....
..there's a risk that if you attempt to cold set the hoop or u-bend it's going to crack around the wielded light mount, and if you attempt to bend the horizontal arms it could prove difficult to mount and dismount the panniers.
Short of making two metal link plates (which have a slight in the middle) and attaching the arms to the link plates and then the hoop to the other end of thr link plates I don't have an answer, and I don't think link plates are great because they'll compromise the rigidity of the rack and look terrible.
I tend to agree - I would send them photos of the measurement of the gap between the rails when the rack is both on and off the fork. Also photos showing that the width of the mid fork mounts is within spec. Quote how far the gap is off spec (I'd include their own spec diagram also so that it's all there in front of them). A major hassle for sure but if they are able to provide you one that is stated spec and that can be used then surely it be worth it. Or if they will work with your fork blade profile then the Tubus clamp mounts might make the rack usable.
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Re: Tubus Tara different?

Post by slowster »

As I posted back on page 2 of the thread, I have a stainless Tara and it similarly measures ~150mm. That measurement is dictated by the positions of the two cylindrical bosses in the U bar. The hole of each boss is at 90 degrees to its respective tube section. Furthermore, the two holes are in the same 2D plane as the majority of the U bar. The bosses are clearly welded in that precise position using a jig.

In other words, both the racks the OP and I have are made like that by design, and I doubt Tubus would be able to replace them with one that fits better. The fact that Spa have confrmed that they often need to bend the racks to fit on some of the bikes they sell seems to confirm that.
PT1029 wrote: 5 Feb 2023, 5:38pm U bar sprung in to 120mm outside dropout width, rack mid fork mount point width 145mm. Actual fork width 120mm, so 12.5mm spacers per side
U bar sprung in to 125mm outside dropout width, rack mid fork mount point width 154mm. Actual fork width 120mm, so 17mm spacers per side
NB. I think Tubus blurb said recc max 8mm spacers.
NB. Using 17mm spacers each side is too much in my view, in terms of bolt stress.
NB. Spinging the U bar into 120/125mm dropout width didn't need that much force, and its a chunky bar, so OK to do in my book.

Tubus rec dropout width of 124 - 134mm, so the 2nd line (in bold) applies.
Tubus rec mid fork width is 130 - 140mm, so 2nd line in bold is 14mm over the upper limit for mid fork width.

If the pannier hook rails were parallel, the mid ford mount width would be 23mm less (no taper) than 154mm, so would be 131mm wide, which is within Tubus spec. of 130 - 140mm width.
I might be misreading or have misunderstood and apologies if so, but the mounting instructions* show the supplied four 8mm spacers** being used both at the drop outs and the mid-fork mounts. Therefore 16mm needs to be added to both the b1 and b2 ranges of permitted dimensions. In other words:

- the spacing of the rack at the drop outs should be between 140mm to 150mm.
- the spacing of the rack at mid-fork mounts should be between 146mm to 156mm.

I am sceptical that Tubus would accept that the racks are out of specification. I suspect that Tubus might acknowledge that at the opposing extremes of the ranges of b1 and b2 dimensions, the fastenings might be tight/somewhat stressed, but maintain that was within the tolerances of their design. They might also point out that they stand behind their design by guaranteeing the rack for 30 years, and for the first 3 years will courier one to you free of charge ASAP wherever you might be on tour.

* https://www.tubus.com/fileadmin/user_up ... .0_web.pdf

** The titanium version is supplied with larger 11mm spacers for the drop out mounting, which indicates that the titanium racks are less tolerant of being stressed than the steel racks, and Tubus have decided the larger spacers are necessary, despite the bolts themselves presumably being subject to more stress with the larger spacers.
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Re: Tubus Tara different?

Post by pwa »

531colin wrote: 6 Feb 2023, 5:53pm
pwa wrote: 6 Feb 2023, 4:17pm Surely the way to narrow a Tara would be to simply sit on the main (forward) U bend, to put it crudely. No welds anywhere near there, and the amount of extra bend would be quite small. The question is, how to isolate the bending to the U itself.
The danger with just pushing the dropout ends of the "U" piece together is its likely to crack or kink at the drilling(s). (Somebody said the drillings also have a tube or boss welded ?)
....this is basically what has happened to Colin 54's rear rack.

I think Colin could have bent his successfully "mid-leg" by placing a bit of wood between the legs below the welds, but to bend the "U" will require force above the drillings, which is trickier.

E bay has plenty of benders for 10mm tube, cheap enough to make hiring one unnecessary. They are of course designed for plumbing, ie copper tube, not for Tubus' thin wall steel tube, which, as we see, can crack!
Yes, I see the need for care. My own inclination would be to go for an application of squeeze to the U tube just above the welds, closer to the main U, using a woodwork clamp with a trigger type mechanism (e.g. Irwin Quick-Grip), and spreading the force on the tube by taping on some wood where the pressure is applied. And I would go for the least amount of cold setting that would do the job, so still requiring a little springing to fit to the fork. This is all assuming that the rack isn't going to require a huge amount of bending, which, I admit, would be pushing one's luck.
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