...why Tubus ships M5 bolts with a 3.5mm hex head?

[LittleGreyCat]

Mainly me venting.
However I am starting to fit a Tubus rear rack and having "issues".
[Note that it is over a year since I bought the rack so a bit late to grumble to the supplier.]

I now realise that the packing list doesn't exactly match the contents of the "bits" pack.
However that should not be a show stopper.
The big nuisance is that the hex M5 bolts to screw into the bike frame have a 3.5mm head size.
I don't seem to have a 3.5mm hex key in any of my various hex key sets.
Most seem to go 1.5, 2, 2.5, 3, 4, 5 etc.

I note that a have 4.5mm hex key, not in a set, presumably bought for a previous unusual head size.

I have at least two M5 bolts with a 4mm socket size so I should be able to proceed until the next unexpected hurdle.
I am just wondering why chose a 3.5mm head size when virtually no sets have that.

[cycle tramp]

Possibly so a smaller allen key is used, so you don't strip the threads in the frame....

..or they hate you...

..go and buy some A4 grade stainless fasteners, which have a greater strength than A stainless and be smug about it..

[scottg]

[snip]
I am just wondering why chose a 3.5mm head size when virtually no sets have that.

Are you sure its metric and not Whitworth ? could be 1/8 BSW
Germans think the Brits still use Whitworth for everything.

[Cadence]

Are they dome, flange head or countersunk screws? These all have smaller hex sockets than cap head screws.

[PH]

That's a bit odd, I don't recall any of my Tubus racks requiring anything other than a 4mm. Have you looked at the instructions? They list the tools required, if you've lost them, they're available online. It could be that they've sent the wrong screws, but that would be very un Tubus like.

[deeferdonk]

The reason will be that the procurement person at tubus will have been asked to purchase M5 bolts from a supplier, and they would have got some quotes and purchased the cheapest ones that met that specification.

[Airsporter1st]

3.5mm allen wrenches may not be common in sets, but they are freely available, e.g:
https://amzn.eu/d/9PQSABZ

[slowster]

I agree with PH. It strikes me as very unlikely that Tubus would supply 3.5m allen key bolts with a rack. Firstly, all the various fastening bits will be purchased by Tubus in very large quantities. If the wrong size bolt was included in a pack, it would be likely that a large number of the packs would be similarly affected, and if that happened there would probably be multiple reports of it that could be found by online searching. Furthermore, it would be less likely that such an unusual bolt size would have got into the supply/packaging make-up chain.

the packing list doesn't exactly match the contents of the "bits" pack.

In what other respects do the contents not match the description?

In my experience Tubus supply the various small parts in resealable plastic bags. So it would not be obvious if at some point someone had broken open the pack and removed or substituted any of the pieces. That said, if the rack was purchased from an online retailer that was largely a high volume 'box shifter', it would be difficult to conceive of circumstances under which it would be likely that the packing would be opened to take out any of the small parts. Conversely, I can imagine that in a bike shop which both fitted the racks to bikes as well as selling the racks without fitting or online, a mechanic might have removed small parts from the packaging of a rack in stock in order to use them on a bike in the workshop, and then later replaced those missing parts with what the mechanic considered near enough equivalents.

[mattheus]

Possibly so a smaller allen key is used, so you don't strip the threads in the frame....

..or they hate you...

..go and buy some A4 grade stainless fasteners, which have a greater strength than A stainless and be smug about it..

Seems the best way to go. Annoying to have to spend extra cash, but you'll feel better, I predict!

[LittleGreyCat]

That's a bit odd, I don't recall any of my Tubus racks requiring anything other than a 4mm. Have you looked at the instructions? They list the tools required, if you've lost them, they're available online. It could be that they've sent the wrong screws, but that would be very un Tubus like.

When I started on this yesterday the bits and pieces were still in a heat sealed bag.
I have the original instructions, and everything seems to be listed as M5 but there are clearly two different sizes of bolts and washers.
There are a number of M6 items including two nylock nuts.
The number of washers of one type are not as listed.
The bolts seem to be correct for the rack so I assume something changed but the instructions were not updated.
Not what you would expect from Tubus.

Aha!
Gone back yet again and the instructions include "tools not included" and one is a Torx T25.
As far as I can tell these bolts are just listed as M5 with no indication of the type of head.
That is one mystery solved, but I am still puzzled that all the bolts are listed as M5 when some are obviously M6, and the included hex key that emerged when I went back and shook the bag again is 3mm, which doesn't match any of the bolt heads apart from the couple I extracted from stock. That might have wandered into the larger plastic bag, of course.
No idea why there is a Torx head instead of a hex head.

Anyway, onwards and upwards.
Now trying to cancel the hex key set with a 3.5mm key included.

[PH]

Gone back yet again and the instructions include "tools not included" and one is a Torx T25.

I wonder if that's a new thing, I don't recall any of the Tubus racks I've fitted coming with Torx screws, it would make more sense, to me anyway, to have one or the other. In which case I'd choose Torx, I've changed most of my fixings, it just feels a more secure connection.

[freiston]

Similar but different, I received and fitted a B&M Cyo IQ Premium Senso Plus (I do not like their names) front light yesterday. It came with a T10 Torx key but the fitting requires a T20 key.

[ferrit worrier]

try on ebay search " 3.5mm hex key " I've just tried it and several pop up.
Good luck

Malc

[Airsporter1st]

try on ebay search " 3.5mm hex key " I've just tried it and several pop up.
Good luck

Malc

I linked to some on Amazon, but OP doesn’t seem interested in that particular solution - as he says “he’s just venting”.

[LittleGreyCat]

try on ebay search " 3.5mm hex key " I've just tried it and several pop up.
Good luck

Malc

I linked to some on Amazon, but OP doesn’t seem interested in that particular solution - as he says “he’s just venting”.

If you read the whole thread you will see that is actually a Torx head.