Handelbars.

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Seth
Posts: 156
Joined: Thu Aug 12, 2010 4:45 pm

Re: Handelbars.

Post by Seth » Fri May 11, 2018 6:35 pm

Wobbly -
I see you're still using the forward mounting holes on the upper clamp.
If you switch to an RT gauge mounting bracket, you can move your bars back to the rear mounting holes.
Shorter reach without raising the bars, and giving more room within the fairing.

Beemerboff
Posts: 48
Joined: Thu Feb 08, 2018 12:11 am

Re: Handelbars.

Post by Beemerboff » Fri May 11, 2018 6:50 pm

Gibson, it is not fine to drill aluminium bars - get your facts right before you post on what is a safety matter with potentially serious consequences!

Wobbly
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Joined: Mon Aug 07, 2017 8:48 pm

Re: Handelbars.

Post by Wobbly » Mon May 14, 2018 4:46 pm

Seth wrote:
Fri May 11, 2018 6:35 pm
I see you're still using the forward mounting holes on the upper clamp. If you switch to an RT gauge mounting bracket, you can move your bars back to the rear mounting holes. Shorter reach without raising the bars, and giving more room within the fairing.
It took a while, but I figured that out. I simply haven't purchased an RT gauge mount yet. All the ones on Ebay simply say "gauge mount", but you're correct, I need the one with the shorter dimension between the 2 mounting positions. It's crazy that BMW handlebar position options rest upon the gauge mount, but there you have it.

In the works, my friend.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

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SteveD
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Joined: Tue Aug 03, 2010 3:29 am
Location: Melbourne, Oz.

Re: Handelbars.

Post by SteveD » Tue May 15, 2018 4:27 am

I might have a RT instrument bracket Wobbly, yours for postage cost from Oz. No idea what that is, but my guess would be around USD20? If they're thin on the ground..it's there. To be sure, I should get dimensions to check. That's if I have one, but I think I do somewhere in a box od bits. I'll check tomorrow.
Cheers, Steve
Victoria, S.E.Oz.


1982 R100RSR100RS supergallery. https://boxerboy81.smugmug.com/
2006 K1200R.

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Gibson
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Re: Handelbars.

Post by Gibson » Tue May 15, 2018 8:51 am

Beemerboff, sorry, You are correct. Renthal warns against this. I suspect even a small sloppy hole with burrs will cause a stress riser as their bars are heat treated and shot peened , I suspect. There are aluminum bars (Woodcraft) that you can drill small locating holes for controls and cut to length. Sorry if I was not clear enough. I still maintain that cutting Renthal bars with a pipe cutter to shorten is fine.

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Gibson
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Re: Handelbars.

Post by Gibson » Tue May 15, 2018 12:07 pm

I contacted Renthal and was informed that any modification including a scratch or punch mark can adversely affect the integrity of their bars and cause failure. They rely on surface hardening for strength and stiffness. I am worried about even a rock chip from a truck. I will be removing these bars from my street bike and replacing with steel. For street riding we have a lot more to loose at 60mph on the pavement surrounded by cars than an off road machine. At the time that I purchased my Renthal bars, this warning was not present. Please disregard my post as it is not ok to modify Renthal bars in any way.

Wobbly
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Re: Handelbars.

Post by Wobbly » Sat May 26, 2018 10:06 pm

SteveD wrote:
Tue May 15, 2018 4:27 am
I might have a RT instrument bracket Wobbly, yours for postage cost from Oz. No idea what that is, but my guess would be around USD20? If they're thin on the ground..it's there. To be sure, I should get dimensions to check. That's if I have one, but I think I do somewhere in a box of bits. I'll check tomorrow.
Many thanks my friend, that's an extremely nice offer. However, these things are extremely common here and it's no problem to find one when and if I need it.

Highest regards.
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

Wobbly
Posts: 247
Joined: Mon Aug 07, 2017 8:48 pm

Re: Handelbars.

Post by Wobbly » Sat May 26, 2018 10:11 pm

Beemerboff wrote:
Fri May 11, 2018 6:50 pm
...it is not fine to drill aluminum bars - get your facts right before you post on what is a safety matter with potentially serious consequences!
It all depends upon the diameter of the drilled hole ! Drilling a 16mm hole in 22mm bars is a definite no-no, while drilling a 3mm hole is probably OK.
Gibson wrote:
Tue May 15, 2018 8:51 am
Renthal warns against this. I suspect even a small sloppy hole with burrs will cause a stress riser as their bars are heat treated and shot peened , I suspect.
Well of course they do. It's much easier to say "No" to all holes, rather than need to inspect every customer's drilled hole and pay an engineer to make a determination about safety. So it's purely a CYA legal defense thing and has nothing to do with reality.

Small round holes do not cause stress risers. If they did, then aircraft makers could not rivet planes together. Sharp corners, as with square holes, cause "stress risers". The beauty of the round hole is that stress flows around the hole exactly becasue it has NO sharp corners.
Gibson wrote:
Tue May 15, 2018 12:07 pm
I contacted Renthal and was informed that any modification including a scratch or punch mark can adversely affect the integrity of their bars and cause failure.
That's a true statement, but what they didn't tell you is whether it's enough to make the bars fail. They are simply taking the easy way out to protect themselves. Think about it, just fitting aluminum bars to the bike puts microscopic scratches on them and they are not as strong. But they still don't fail.
Gibson wrote:
Tue May 15, 2018 12:07 pm
They rely on surface hardening for strength and stiffness. I am worried about even a rock chip from a truck.
But installing a small hole does not reduce any of the surface hardening, unless you use a cutting torch ! If you get a gouge 3mm deep and 30+mm long, then sure, replace the bars. If you catch a rock that leaves a crater 8mm deep and 10mm in diameter, then sure, replace the bars. Use some common sense and you'll be OK.

Hardening (and thereby strength) would be reduced by high heat processes such as welding, grinding, power sawing, any process involving a torch, etc. Again, you simply have to use some common sense here.

;)
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

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Gibson
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Re: Handelbars.

Post by Gibson » Tue May 29, 2018 3:56 pm

I know, but I received a rather harsh response that I should know all the facts before I post. If drilling a small hole causes a stress riser, then why do we do it to stop a crack from propagating? I have a lot of metalworking experience. We used to make racing outboard fins out of 6061 T6.(T-8 would break). Renthal would not reveal the alloy, or the hardening process. I really just wanted to avoid any type of conflict...

Kurt in S.A.
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Re: Handelbars.

Post by Kurt in S.A. » Tue May 29, 2018 4:27 pm

At the tip of a natural crack, the stress risers are huge. Stop drilling reduces that stress riser down to something "reasonable", but it's only a stop-gap measure. In the aircraft industry, stop drilling is not allowed. Typically, any crack that is found needs to have the part replaced or a hole oversized.

As I recall, my /7 front forks have a hole in the side of it about midway down. The proper orientation of the tube is with the hole pointing towards the other tube (or exactly away from the other tube). The reason would be that the highest points of bending stress when the forks are flexing fore-aft is on the forward or aft side of the tube. The state of minimum or zero bending stresses are at the midpoint between the front and back size. Torsional stresses affect any imperfection around the diameter of the tube, but the front forks are not being subjected to torsional loading. So the hole in the position I describe should be fine for typical bending stress environments.

Kurt in S.A.

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