Author Topic: Dome headed Allen bolts for a fixed hub  (Read 2064 times)

Nelson Longflap

  • Riding a bike is meant to be easy ...
Dome headed Allen bolts for a fixed hub
« on: February 16, 2018, 04:12:32 pm »
The wheels on my Genesis Day One fixed are held on with m6 dome headed Allen bolts 25-30mm long. One of which has been removed and replaced enough times with Allen keys of variable quality that the socket head is now sloppy. Can anybody point me to a source for these bolts please? Local bike shops don't stock them, nor generic suppliers like screwfix. Cap-headed bolts are easy to source; I could use these combined with suitable washers but am looking for a like for like replacement if possible. Best quality would be good. I don't mind buying two or four for future-proofing.

Given the choice I'd prefer proper track nuts, but the Allen bolts perform ok, until worn out, and it seems daft to discard a wheel for the sake of a bolt!

TIA
The worst thing you can do for your health is NOT ride a bike

Re: Dome headed Allen bolts for a fixed hub
« Reply #1 on: February 16, 2018, 04:33:35 pm »
This ebay store does them reasonably cheaply in different lengths.

https://www.ebay.co.uk/itm/M6-Flange-Bolts-Button-Dome-Head-Bolts-Allen-Screws-Made-From-A2-Stainless-Steel-/111419417922

Not sure if A2 grade steel is OK for this application but maybe someone else knows?
I think you'll find it's a bit more complicated than that.

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: Dome headed Allen bolts for a fixed hub
« Reply #2 on: February 16, 2018, 04:53:04 pm »
Thanks pcolbeck, I don't know what A2 stainless means either (I've also seen A4). If I'm being picky (which I am) I'd prefer no flanges in order to match the originals. (And £1.20 for the bolts, plus £13.95 postage highlights a disadvantage of online shopping!) As I said I could bodge cap head bolts to fit, but they wouldn't look as sleek as the dome headed ones ...
The worst thing you can do for your health is NOT ride a bike

LittleWheelsandBig

  • Whimsy Rider
Re: Dome headed Allen bolts for a fixed hub
« Reply #3 on: February 16, 2018, 04:59:17 pm »
A2 is 304, A4 is 316.

316 is generally more corrosion resistant than 304 but slightly more brittle. Most 316 bolts are somewhat stronger than most 304 bolts but there is a lot of overlap.
Wheel meet again, don't know where, don't know when...

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: Dome headed Allen bolts for a fixed hub
« Reply #4 on: February 16, 2018, 05:39:16 pm »
Thanks for the tutorial LWaB 👍 - it looks like A4/316 is preferable, given a choice.
The worst thing you can do for your health is NOT ride a bike

Re: Dome headed Allen bolts for a fixed hub
« Reply #5 on: February 16, 2018, 05:54:08 pm »
Six probably have some in the workshop but I am not there until Tuesday.
I will report back.
Welding, fabrication and light engineering available to forum members.

Re: Dome headed Allen bolts for a fixed hub
« Reply #6 on: February 17, 2018, 06:58:56 pm »
It's a button head you're looking for, but personally I'd fit a cap head + washer.  Button heads usually use a smaller hex socket than the same size cap head and hence are easier to round out than a cap head.

Re: Dome headed Allen bolts for a fixed hub
« Reply #7 on: February 17, 2018, 10:20:00 pm »
Sanity check... Did you really mean M6? That's a weirdly small fastener for fork ends which were normally designed for 3/8" or 10mm axles. A quick check shows that a Screwfix M6 cap screw has a head just under 10mm diameter, which is going to make demands on washers which would would not be good for the fork ends. I think the cap screws on the Goldtec are M8 & I have more than enough problems with washers for those screws.

handcyclist

  • watch for my signal
Re: Dome headed Allen bolts for a fixed hub
« Reply #8 on: February 18, 2018, 02:26:59 pm »
Thanks for the tutorial LWaB 👍 - it looks like A4/316 is preferable, given a choice.

What Little and Big says above is accurate but it's really not worth paying more for A4, unless you regularly dip your bike in the sea or leave roadsalt on it all year.
Doubt is is not a pleasant condition, but certainty is absurd.

Re: Dome headed Allen bolts for a fixed hub
« Reply #9 on: February 18, 2018, 02:46:27 pm »
It's a button head you're looking for, but personally I'd fit a cap head + washer.  Button heads usually use a smaller hex socket than the same size cap head and hence are easier to round out than a cap head.

Chris n's taken the words right out of my mouth.
Button heads do use an allen key, one size down from the equivalent cap head.
Fit cap heads and forget about the problem.
BETD do some nice cap heads with a cupped / stepped washer.
If you are really looking for driver / tool efficiency,  with least damage to the fastener,  then Torx is the way to go.

Re: Dome headed Allen bolts for a fixed hub
« Reply #10 on: February 19, 2018, 09:30:21 am »
Sanity check... Did you really mean M6? That's a weirdly small fastener for fork ends which were normally designed for 3/8" or 10mm axles. A quick check shows that a Screwfix M6 cap screw has a head just under 10mm diameter, which is going to make demands on washers which would would not be good for the fork ends. I think the cap screws on the Goldtec are M8 & I have more than enough problems with washers for those screws.

Goldtec do use M8 screws, but they're better designed than most track hubs. ;)  The axle is quite a large diameter and has flats on each end that are 10mm across.  Using M8 internal threads in a M10 or 3/8" axle won't leave much (if any) material in the wall.

The majority (inc. my Surly hubs) seem to use M6 screws in a straight hollow steel axle with a 5mm minor diameter (for a QR).

Re: Dome headed Allen bolts for a fixed hub
« Reply #11 on: February 19, 2018, 05:01:17 pm »
It's more than time to answer OP's question. The last lot of s/s fasteners I bought came from Kay's Fasteners. I've never had corrosion problems with A2 stainless on my bikes. The one-gear-fits-all bike is used in all weathers, & usually only gets displaced by the invalid carriage for medical reasons or if it's very hilly. Many of the roads I use in frosty weather are salted. In winter the bikes are normally only washed when the trees they're parked under while I'm beating up nature reserves let the rain through.

But, purely to satisfy my curiousity, does the Genesis Day One have chain tugs?

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: Dome headed Allen bolts for a fixed hub
« Reply #12 on: February 20, 2018, 04:49:40 pm »
But, purely to satisfy my curiousity, does the Genesis Day One have chain tugs?
Thanks for the comprehensive answer CN; the Day One doesn't use chain tugs of the traditional variety, but has what I'd call 'chain tensioners', ie Allen screws that operate through the closed end of the forkend to push the wheel backwards. They're not as strong as tug nuts but I find them really effective for maintaining chain tension, with the minor hassle of having to slacken them in order to remove the chain to get the wheel out.

It's a button head you're looking for, but personally I'd fit a cap head + washer.  Button heads usually use a smaller hex socket than the same size cap head and hence are easier to round out than a cap head.

Chris n's taken the words right out of my mouth.
Button heads do use an allen key, one size down from the equivalent cap head.
Fit cap heads and forget about the problem.
BETD do some nice cap heads with a cupped / stepped washer.
If you are really looking for driver / tool efficiency,  with least damage to the fastener,  then Torx is the way to go.
Thanks both. The button heads do look nice, but are hard to source in the exact size. <Retrieves vernier calipers> Mine are 5.9 mm diameter across the thread, which I took to be M6. The socket depth is 4.6 mm which I agree is shorter than cap-heads, and the head diameter is 13 mm. It looks as though I'll be going the cap head route; I have a reasonably good stock, but your links will be useful if I get stuck. Thanks again  :thumbsup: :thumbsup:
The worst thing you can do for your health is NOT ride a bike

Re: Dome headed Allen bolts for a fixed hub
« Reply #13 on: February 20, 2018, 05:03:28 pm »
Sanity check... Did you really mean M6? That's a weirdly small fastener for fork ends which were normally designed for 3/8" or 10mm axles. A quick check shows that a Screwfix M6 cap screw has a head just under 10mm diameter, which is going to make demands on washers which would would not be good for the fork ends. I think the cap screws on the Goldtec are M8 & I have more than enough problems with washers for those screws.

Goldtec do use M8 screws, but they're better designed than most track hubs. ;)  The axle is quite a large diameter and has flats on each end that are 10mm across.  Using M8 internal threads in a M10 or 3/8" axle won't leave much (if any) material in the wall.

The majority (inc. my Surly hubs) seem to use M6 screws in a straight hollow steel axle with a 5mm minor diameter (for a QR).

I think the Goldtec axle is aluminium which has to be oversize. And it looks like the screws are off the shelf items.

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: Dome headed Allen bolts for a fixed hub
« Reply #14 on: February 21, 2018, 01:59:55 pm »
I think the Goldtec axle is aluminium which has to be oversize. And it looks like the screws are off the shelf items.

I have a Goldtec hub on another bike, and the screws are oversize. Not really sure about the longevity of aluminium either.

On the whole I prefer track nuts, and put up with carrying a spanner; an old idea that ain't broke ...
The worst thing you can do for your health is NOT ride a bike

Re: Dome headed Allen bolts for a fixed hub
« Reply #15 on: February 21, 2018, 02:23:37 pm »
I've just had a look at the bolts on my Goldtec hubs - they're stamped A2.
I've been using the same bolts on the Pompino since 2013, I do them up b@st@rd tight, and although there is some deformity in the socket, there's plenty  of life left in them.

Re: Dome headed Allen bolts for a fixed hub
« Reply #16 on: February 21, 2018, 05:55:59 pm »
But, purely to satisfy my curiousity, does the Genesis Day One have chain tugs?
Thanks for the comprehensive answer CN; the Day One doesn't use chain tugs of the traditional variety, but has what I'd call 'chain tensioners', ie Allen screws that operate through the closed end of the forkend to push the wheel backwards. They're not as strong as tug nuts but I find them really effective for maintaining chain tension, with the minor hassle of having to slacken them in order to remove the chain to get the wheel out.

It's a button head you're looking for, but personally I'd fit a cap head + washer.  Button heads usually use a smaller hex socket than the same size cap head and hence are easier to round out than a cap head.

Chris n's taken the words right out of my mouth.
Button heads do use an allen key, one size down from the equivalent cap head.
Fit cap heads and forget about the problem.
BETD do some nice cap heads with a cupped / stepped washer.
If you are really looking for driver / tool efficiency,  with least damage to the fastener,  then Torx is the way to go.
Thanks both. The button heads do look nice, but are hard to source in the exact size. <Retrieves vernier calipers> Mine are 5.9 mm diameter across the thread, which I took to be M6. The socket depth is 4.6 mm which I agree is shorter than cap-heads, and the head diameter is 13 mm. It looks as though I'll be going the cap head route; I have a reasonably good stock, but your links will be useful if I get .stuck. Thanks again  :thumbsup: :thumbsup:

Your button heads sound rather special. After I'd posted I measured some of my screws. The M6 cap screws have a socket 3.5 mm deep. The button heads' are only 2.5 mm deep. Depth is critical since a shallow socket doesn't support the Allen key well. That is normally only critical when the wheel has to be removed on a cold wet night to fix a puncture. Is it possible to get Genesis replacements? Meanwhile, cap screws will need decent washers - ideally form C, though form A may be OK. Both are 1.6 mm thick. With your chain tensioning screws, the axle screws shouldn't need to be especially tight.

My preference fwiw would be a good quality q/r skewer.

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: Dome headed Allen bolts for a fixed hub
« Reply #17 on: February 21, 2018, 07:11:04 pm »
Your button heads sound rather special. After I'd posted I measured some of my screws. The M6 cap screws have a socket 3.5 mm deep. The button heads' are only 2.5 mm deep. Depth is critical since a shallow socket doesn't support the Allen key well. That is normally only critical when the wheel has to be removed on a cold wet night to fix a puncture. Is it possible to get Genesis replacements? Meanwhile, cap screws will need decent washers - ideally form C, though form A may be OK. Both are 1.6 mm thick. With your chain tensioning screws, the axle screws shouldn't need to be especially tight.

My preference fwiw would be a good quality q/r skewer.
Thanks very much Nick, I didn't know those details. The expertise of forumites is what makes yacf special.  :thumbsup:
The worst thing you can do for your health is NOT ride a bike

Nelson Longflap

  • Riding a bike is meant to be easy ...
Re: Dome headed Allen bolts for a fixed hub
« Reply #18 on: March 10, 2018, 04:11:15 pm »
My preference fwiw would be a good quality q/r skewer.

By way of a conclusion, I followed Crumbling Nick's preference, and on a short test ride it works very well, using an old Hope QR from the pile of miscellaneous stuff. I'll see how it performs hammering up some hills tomorrow. Always my biggest worry on fixed wheel is spinning wildly downhill on the edge of control; I'll save that test for later.
The worst thing you can do for your health is NOT ride a bike