# Welding Aluminium



## 18bikes (Jan 15, 2007)

I've got a project coming up that I think might be better if done with aluminium. This is not a complete frame, a subassembly if you like. The part I would need to weld to is made of either 6xxx (can't remember which alloy) or 7020. I've ruled out the 6xxx due to heat treatment and am planning to go with the 7020 and age it in my home oven. I plan to use 7005 tubing from Nova. I'm pretty happy with these decisions, but if someone (pref in the UK) knows how to get round the heat treatment issue I'm ready to listen.

My question relates to choosing a filler material, my initial research suggests that 7020 and 7005 are very similar alloys so I shouldn't have a problem finding a filler. But the suggested filers I have found are 5xxx series, does this sound right? Does the fact that the part is forged make a difference?

The other question is about filler diameter. As I don't have the part in hand I don't know the exact wall thickness but it is likely to be about 2-3mm. It seems like this is a border between using 1.6 and 2.3mm filler. My instinct is to err on the side of caution and go for the smaller filler and increase feed rate if needed. Am I barking up the wrong tree?

I'm planning to get the filler and do some practise on some offcuts before tackling the actual part but any pointers for an experienced TIG welder who's not done much al would be very helpful

If anyone can suggest a good source that will explain how I can work these things out, rather than just telling me an answer that would be greatly appreciated.

thanks,
matt

P.S. I did do a search and found a bit of info regarding 7xxx vs 6xxx but nothing about filler choice


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## RCP FAB (Jun 15, 2011)

I haven't and don't work much with 7000 series aluminum, but 5356 is recommended for joining most 7000 series aluminum.

I would also use 2.3mm for material 1.5mm up to about 3 or 4mm.

This chart has never let me down for filler rod type:

Aluminum Filler Rod Selection Chart - Duramax Diesels Forum


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## Crispy01 (May 4, 2011)

Interesting article for you, from my understanding aluminum get stiffer the longer it sits around, that's why heat treating is called aging. 7000 series aluminum can age to the desired stiffness over a few days, whereas 6000 series often take a month plus and still not be at the desired stiffness let alone ever reaching it.

Aluminum alloy 7020T6 - Materiály - Duratec

With regards to filler choice, i would go 2.4, aluminum is always better with the larger filler as most people inexperienced with it will have a nightmare trying to chase it balling up on the end and dropping off all the time.


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## smudge (Jan 12, 2004)

FWIW I have almost zero experience welding aluminum but I too am interested. I recently visited with a local builder who builds quite a few aluminum production frames and he told me a few things that stand out.

1. preheat it before you weld it. He said that it *can* crack on its own if you weld two pieces together that have dissimilar thicknesses

2. regardless of the alloy, the joints are super soft after welding and to be aware of how the parts will be affected by handling and gravity after you've welded it.

that's all I've got, just in case you didn't already know. Please share your experience when you're done.


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## customfab (Jun 8, 2008)

I wold go with 1/16 filler for something of that thickness. If you want anything smaller than that your probably going to have to get mig wire. 

Welding aluminum is completely different from steel. If you can't afford to scrap your project make sure you feel comfortable before you start. The biggest thing I'll tell you about welding aluminum is that you want the weld in the metal not on top of it. A lot of bike companies seem to lay big honking aluminum welds on their frames, this isn't what you want. Personally I think Cervelo has some of the best aluminum frames on the market. It pains me to say that as I despise those arrogant pricks. If you can track one down you'll see what I mean by 'in' the metal. 

I don't think pre-heat is at all necessary for your project, but that's just me.


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## 18bikes (Jan 15, 2007)

Thanks for all the help. Unfortunately the thickness is a bit of a guess until I get the part in my hand so I may be back to ask again once I've got it. I'm not too concerned about having to scrap the part as my fallback is to make it out of steel. The welding/treatment isn't the only thing that could make it non-viable in aluminium.

I managed to aquire some aluminium filler rods (5356) yesterday and have a go on some scrap I had already (unknown alloy). Here is my first attempt


1st test piece by 18bikes, on Flickr

I don't think it's too bad all things considered and with a bit more time under the hood I think I'll get it nailed. Any constuctive critisism is welcome but please bear in mind this pic is literally the first attempt, I did a few more after which did improve. The filler is 2.4mm and I deffinately think I will need this thickness, don't fancy feeding it in like a mad man.

Is there a more scientific method of working out whether pre-heat is needed. Based on volume maybe?

I'm going to get the part ordered (plus some tubing) and have a bit more practise. I'll read up a little more on fillers but it seems like I'm looking at the right options.

I'll keep the thread updated as I find out more

Thanks again,
Matt


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## RCP FAB (Jun 15, 2011)

You do not need to preheat at all on materials that thin. What machine are you welding with? Can you post some more pictures of the welds? Something just looks off it that pic, I can't tell if it's the weld or the angle of the pic.

Are you pulsing with the pedal?


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## 18bikes (Jan 15, 2007)

I've not got any better pics at the moment, I'll take some better ones when I've done a bit more. I can't realy remember if I was pulsing on that pass, I think by the end of my test pieces I'd moved to running constant and not pulsing (which I normally do in steel). It's a Miller Dynasty 200DX. What looks 'off' about it?

thanks
matt


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## RCP FAB (Jun 15, 2011)

I'm not sure by that pic, can you post up how you have the machine set up? Maybe we can start there.


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## Crispy01 (May 4, 2011)

I think it looks a bit cold and when welding aluminum you get better penetration without a gap.
You really want to judge your heat by what it looks like on the other side.


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## customfab (Jun 8, 2008)

Needs more heat and not a little bit. That weld is definitely sitting on top of the metal. When you can see the 'milk line' on the back side of the joint you know it's hot enough. 

Was your material that clean before you started? Aluminum is a dirty metal and it definitely welds way better when it's sano.


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## Rody (Sep 10, 2005)

Matt,

I do a ton of welding on Al and Magnesium for locals who always tend to find me for projects that are "to thin" for the mig equipped weld shops around here.

A few tips...

- The oxidation layer on AL must be mechanically removed for the best weld results. I degrease, soap and water wash, hit it with a dedicated stainless brush, then with a 3M Scotchbrite pad, then acetone, on BOTH sides if possible.

- The desire to pre-heat is to save precious argon and time. AL conducts your heat away readily, so by pre-heating thicker parts, you will achieve a good depth of penetration more quickly. In mis-matched thicknesses, pre-heating the thicker member allows both sides to come to temp more evenly, protecting against the thinner material peeling away from your torch while the thicker piece laughs at your tiny current input. Not necessary on bike tubing.

- I run most AL and Mg with constant A/C current. You'll find that you will have a variable travel speed; slower at first as the heat level builds in the parts, then quickening as you reach the prime temp for penetration. Pulsing always tended to take too long to get to the top of the bell curve for me...would rather run the hotter edge and get the piece welded with good visual penetration and filler that flows in, rather than sitting bulbously on top.

- 7xxx series AL is preferred for one off and small run projects, as it can normalize at room temp with some calendar patience. 

- Forged parts, no matter how clean, always tend to pop/spit/release gas while welding with enough heat to get good penetration. Clean/prep it well, set your weld balance to a higher clean ratio, and move smoothly with a smaller filler, feeding consistently and quickly. This will allow you to flow in the filler material at a more constant rate, suppressing some of the potential for the forged part to off gas and give you contamination issues.

- Keep a supply of tungsten at the ready, so if you do contaminate the electrode, you can quickly change it up before losing a lot of your built up heat, allowing you to keep moving.

- I normally weld sans gloves or with light weight golden needles. With AL, I actually break out the light weight leather gloves, cause the stuff gets hot further from the weld zone, usually right where you need to rest a hand.

That's all I can think of for now...best of luck.

rody


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## TrailMaker (Sep 16, 2007)

^^^ That is GREAT info, Sir;

If there were a welding FAQ type thread stickied to the top of the forum (which might be a good idea), then this post should definitely be in it!

:thumbsup:


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## RCP FAB (Jun 15, 2011)

Rody said:


> I run most AL and Mg with straight current.


You run DCEN on thin aluminum?

While DCEN is used to weld aluminum, it's usually done with ultra pure helium, on HEAVY aluminum.

Matt, for your application, I would recommend setting your machine to

A/C
Amperage: 150-200a
A/C Freq: 100-120hz
A/C Balance: 70-75%
Waveform: Advanced or soft, see what you like better
Tungsten: 2% Lanthanted, Sharpened and then slightly blunted

Hope that helps

Ryan


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## Rody (Sep 10, 2005)

Ryan,

As a point of clarification, I run A/C, non-pulsed. Sorry for the confusion, had been up for over 30 hours and was not as eloquent with my thoughts as I should have been for posting.

r


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## RCP FAB (Jun 15, 2011)

Rody said:


> Ryan,
> 
> As a point of clarification, I run A/C, non-pulsed. Sorry for the confusion, had been up for over 30 hours and was not as eloquent with my thoughts as I should have been for posting.
> 
> r


Gotcha :thumbsup:


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## 18bikes (Jan 15, 2007)

Thanks for all the info guys, lots to take in and have a go at. 

The practise welds were done with what I had so I know it could be cleaner (just used my normal scratch brush not a dedicated aluminium one) and didn't do any chemical cleaning. Now I know I'm not completely useless I will be getting a few materials in (stainless scratch brush, more filler, tubes and tungstens) and have a proper play with settings on the actual material I'll be welding. Once I've done some more I will post results in this thread

Thanks,
Matt


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## snydercj7 (Jun 12, 2008)

How is the penetration on the back side?


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## 18bikes (Jan 15, 2007)

Made a bit of progress on this. Finally got the forging through that I will be welding to but haven't measure the thickness yet, looks to be something like 2-4mm (hard to measure/eyeball the bit where I will be welding to as it's thicker at the edges). I've done a bit more practise welding, taking on the advice above. I need to have another read of the welder manual and fiddle with some settings. I'm going to be ordering some tubing and more filler so I can practise with the actual stuff.

This is a (really crap) picture of one of my recent welds. It's just some offcuts of steerer tube so not sure on the alloy but they certainly look better than my other attempts. They also look better in the flesh than this pic

Picture

I know it all needs to be cleaner but any other input is welcome

Despite most people telling me that aluminium welding is hard, I have found it much easier, particularly on the thicker pieces. I've found that running very hot, with no pulse (manual or otherwise) and using the filler to control the 'stack of dimes' look I've managed to get reasonable good welds with very little practise. I'm hoping that once I've made some tweaks to set up, got the proper material and done a bit more practise I'll have it nailed.

I've been talking to a few people about the aging and I think I've got that covered too

I'll keep updating this thread as I make more progress,
Matt


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## 18bikes (Jan 15, 2007)

I've done some more practise with the settings mentioned above and I've settled on 200 ams, 120hz, 60% balance but as this is only practise material this may still change. I need to programme so down slop into the machine and I've still not got round to ordering a dedicated brush for cleaning when I stop/start. I need to get feeding a little quicker to get the beads closer together but other than that I think I'm doing ok. What do people think?
Joint 1
Joint 2

These are only the 3rd and 4th tube joints I've done, with 5 or 6 pieces of sheet before that so I don't feel too bad at all. This is still offcuts of steerer tube so not perfect practise. I'm going to be ordering proper tubes this week so will probably hold off on the practise until I recieve that

Matt


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## customfab (Jun 8, 2008)

Stop worrying about your machine settings and run some more practice parts. Those look like hell, keep your hood down and keep at it. Putt your dips of wire a lot closer together. And try to narrow the bead a little bit.


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## zank (May 19, 2005)

that steerer is anodized. you need to get that oxide off. are you using a pedal? that overrides upslope and downslope.


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## RCP FAB (Jun 15, 2011)

This is the first time I've welded Aluminum in about 6 months, so it took me a few tries to lay a nice looking bead.

This is 3mm 6063 aluminum to 3mm 6061. 3/32" 4043 filler. 
Machine set at 140 amps, maybe using 110-120 (no pulsing, manual or otherwise)
75% A/C Balance
120 hz

By no means do I consider this a great weld, but not bad for how rarely I weld alum these days.


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## RCP FAB (Jun 15, 2011)

So you peaked my interest. I would first, get some good material. I set up a joint exactly like the one you pictured, a machined down piece of steerer tube, cleaned it inside and out with acetone. I had a hell of a time welding it with 4043, I don't know if its crappy metal, or a not too happy about being welded alloy of aluminum.

The last 3 pics are of known 6061, that I did not clean up at all due to laziness.


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## zank (May 19, 2005)

could the steerer be a 2000 series alloy?


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## RCP FAB (Jun 15, 2011)

It could be, or it could be something else. Aluminum is a funny metal to mess around with because you never really know what it is.


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## compositepro (Jun 21, 2007)

zank said:


> could the steerer be a 2000 series alloy?


I suggested this to matt off air


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## 18bikes (Jan 15, 2007)

Thanks for all the feedback, I'm going to be ordering some tubes today for practise. I only used the steerer offcuts as we already had them and I wanted to check that it's even remotely feasible that I can weld aluminium. I know I'm not there yet but I'm happy that I can at least join bits together I will try on some stuff that I can be certain of what it is.

RCP FAB - I'm suprised how low you have your machine set, maybe I'm not using as much pedal travel as I thought I was but I'll try turning it down a bit and pay attention to how much travel I'm using so I can get a better idea of what current I'm actually using

Hopefully I can get some material ordered today and will manage some more practise later in the week


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## zank (May 19, 2005)

i'd get some flat sheet too. just run beads and get used to what you are looking at.


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## zank (May 19, 2005)

I've been filling up sheets with beads. This is a 12"x 12" piece of 0.0625" 6061. The eventual goal is to travel the whole width in one go. This is a great exercise because as the piece heats up, you have to keep backing off the pedal. You can practice your bead width, dabbing frequency and deposition amount, and travel speed. The wide width gives you plenty of room to get in a nice pace and keep going rather than having to stop at the end of a piece of metal just as you are getting into a groove. I've been using 3/32" 5356 filler, and that's about 360" worth (10 36" sticks). My machine is a basic transformer machine, so it doesn't have balance control and frequency is set at 60Hz. But I find I can control the cleaning band to some extent with amps and travel speed.


Al practice by Zanconato Custom Cycles, on Flickr

T joints are good practice for tubing.


Al practice by Zanconato Custom Cycles, on Flickr

The challenge for me doing tubing is that you move faster welding aluminum than you do steel, so your optimum torch angle is changing faster. This really challenges your muscle memory and rolling your wrist as you move around the joint. These are 1 3/8" OD x 0.049" wall.


Al practice by Zanconato Custom Cycles, on Flickr

Go back and fill up those two pieces you butt welded.


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## DWF (Jan 12, 2004)

Zank gets it: Practice, practice, practice. 

Some other basic tips: don't over clean (which gives you that big frosty white margin around your weld bead), find the right balance between cleaning and penetration, and don't snap the heat off at the end of the weld, that's what's causing those big suck holes.


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## zank (May 19, 2005)

hey, some of us don't have balance control and can't avoid the wide cleaning zone ;-)

and yeah, crater control is more challenging compared to steel.


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## DWF (Jan 12, 2004)

zank said:


> hey, some of us don't have balance control and can't avoid the wide cleaning zone ;-)
> 
> and yeah, crater control is more challenging compared to steel.


I wasn't really talking about your work, more to the thread in general, but I thought you had a Syncrowave or a Dynasty? It's a lot more challenging when you don't have arc controls but you can still play with your tungsten shape/size/chemistry.


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## zank (May 19, 2005)

Nah, I just have a Lincoln Squarewave TIG 175. Two knobs. One to choose DCEN/AC/DCEP and one to adjust amps. Someday I'll have a machine that I can adjust the waveform on.


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## edoz (Jan 16, 2004)

Another thing to think about is that when you're doing practice pieces you've got less of a heat sink than if you were welding a whole frame and that will change things a little. You may find welding a frame more forgiving in that the practice pieces get fully heated up sooner and you'll need to back off the current sooner and a lot more.


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## 18bikes (Jan 15, 2007)

*I'm back!!*

I finally got some practise material, more filler, brushes and some time so here are my results.

DSCF4994 by 18bikes, on Flickr

I think I'm getting it, but need to not be afraid of more heat. The weld isn't sitting on top so much, and I've sorted the bead spacing. I'm still not getting good penetration and I had the pedal floored so I need to turn the welder up a touch (was at 140A for these) and have another go at it. The numbers are the order they were done in. Any critique welcome


DSCF4995 by 18bikes, on Flickr

These two are among the better ones


DSCF4996 by 18bikes, on Flickr


DSCF4997 by 18bikes, on Flickr

Matt


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## zank (May 19, 2005)

All of that empty canvas. Fill it up with pretty beads!

Keep experimenting, Matt. Great work. Run an edge weld around all of those sheets and then just stack stringers in a straight line next to each other. Overlap a bit and watch the toes washing into the base metal. Run hot. Run cold. Run slow. Run....you get the idea. Don't let all of that space go to waste ;-)


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## TrailMaker (Sep 16, 2007)

Hey;

Getting better.

As Zank infers, the easiest you will have it - the baseline trial - is stacking dabs in a line on a flat surface. If you cant do that to "perfection," there is arguably no point in going further. Do Ray Me Fa So La Ti Do, eh? Repeat, study, repeat, tweak, repeat, refine, repeat. Just like doing endless scales on a piano. It is boring as hell until you allow yourself to realize that you are getting better at it, and it will pay off big-time later. I am forced to admit, to my chagrin, that I've had that much patience. That's how I can fully understand the value of it!! 

Welding on the flat allows you to skip having to deal with differing surface tensions and two heat sinks that must be balanced with an arc that only wants to go to one side at a time, and all the other problems associated with working on two pieces of metal simultaneously. It's where you can most easily learn timing & movement, dab placement & flow out, heat soak, and all the other little intricacies. K.I.S.S.

Using thick-ish material (1/8th or more) will also allow you to "see & feel" the heat come into the metal better because it happens more gradually and is therefor more quantifiable and controllable. Thin stuff goes from zero to blow out far too fast to be of much use in learning to feel the heat range.

If you feel you've gotten that down pretty well, switch directions. When you can do that, go fore & aft instead of side-to-side. Do circles. Weld uphill and down. Then switch hands. Then, switch feet. Yeh... I don't have that kind of patience either, but all of that is great stuff to be able to do if you have the concentration for it.

Doing a flush lap joint would be the next step in the progression, and only slightly more difficult. This step is important because it will clearly show you how much penetration you are getting on the back side of the seam.

Next up would be an overlapped joint. Doing what I call a drop fillet - where you melt the upper piece as filler and fuse it to the lower piece - is pretty easy, and fun. Adding filler to create this lap fillet (when melting the upper piece is not appropriate) is a bit more difficult. Beyond that, anything of a fillet nature (over 30* or so) will be much harder, and will be a step too far in the progression until you've mastered the easiest ones.

It all builds on itself. Makes me want to go practice!


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## bikeabuser (Aug 12, 2012)

Don't know if this will help you, but someone might find it useful - Tig Welding Aluminum - How to Tig Weld Aluminum - Aluminum Tig Welding Beads - YouTube

One of the better Channel's I know of - weldingtipsandtricks - YouTube


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## 18bikes (Jan 15, 2007)

*Update!*

So a bit of an update now I've got the frame finished. This should also explain why I was tied in to aluminium slightly.

We got asked to build a frame with the new Pinion gearbox. Pinion only make their mounting bracket (they call it the 'bridge') in 6000 or 7000 al, no steel option (yet). I was originally going to recreate the aluminium piece in steel but after a conversation with a friend who deals with composites, he suggested a bonded structure may be easier (less machining) and lighter. I've not done any weight comparisons as I've not made a steel version but the frame came out at 5.5lbs for a med/large 853 hardtail with swinger dropouts, tapered headtube, 31.6 seat tube based around a 150mm fork. All things considered I don't think that's too bad.

So first I had to creat my dummy bottom bracket 'lug' using the bridge piece supplied by pinion. Once I was happy with my welding everything was mitred, the aluminium tubes had an external taper machined onto them to remove visual weight and they were welded together. The whole unit was heat treated in my home oven (careful use of a thermometer to ensure accurate temperature) then blasted.


Bridge piece weight by 18bikes, on Flickr

Then the rest of the tubes were bonded in and the frame completed.


Finished Frame (Side View) by 18bikes, on Flickr

It certainly wasn't the easiest way of doing it and I'm not 100% sure if it is lighter than a steel version, but i don't think I could have made a steel version lighter. There are lots of pictures on Flickr and I'm happy to answer any questions you have.

Thanks for all the advice
Matt


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## mickuk (Jul 6, 2007)

I saw this on your flickr last week - suddenly explained your need for aluminium welding. I presume it will be on display at bespoked? (I'll be in new-builder room - ironworks frames).


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## Walt (Jan 23, 2004)

That is awesome. Nice work! It looks like (to me, a total aluminum goober) that you've got the welding down pretty well and that piece came out gorgeous!

Is there any reason you couldn't just use the drive body of the gearbox as a structural part of the frame to allow just welding your tubes to some separate bolt-on plates?

As an aside, though, I hate planetary gear systems. Like pedaling in sand, and I think I've tried 'em all (ie Hammerschmidt, Schlumpf, Rohloff, Alfine, etc) at one point or another. I wasn't even willing to run one on my cargo bike (the least fast/efficient thing ever) because it drives me crazy to have the drivetrain sucking up that much energy. It's like riding when you're having a really bad day and feel awful - all the time. 

-Walt


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## 18bikes (Jan 15, 2007)

Yes the bike will be at Bristol, come and say hello

The gearbox cannot be used as a stressed member so would need steel connecting the tube ends together, I've got ideas on how to do it but I don't think it will be light. One advantage of the bonding method was the alignment was absolutely spot on.

The pinion isn't planetary, it's like a motorbike gearbox. I've not ridden it yet but can't wait to give it a try

Matt


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## Walt (Jan 23, 2004)

Well, planetary or not, if you're meshing gears and then driving a chain, the efficiency is going to be pretty bad depending on how you lubricate the system and what kind of gears you decide to use. Have they measured it? 

Too bad that they did not design the box as a structurally capable member, that would really simplify building frames with a variety of materials. My guess is that steel/ti is not really on their radar anyway, though, so the aluminum plate/shell/adapter is probably the way it'll be.

Anyway, sorry for the hijack. Awesome work!

-Walt


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## 18bikes (Jan 15, 2007)

I don't think Pinion have measured in the same way rohloff have but when rohloff did it it was only a handfull of % diff to a 'normal' set up (both being low 90's) the main difference being that the rohloff efficiency stays there regardless of conditions whereas a mech falls off pretty sharpish. The pinion should be better simply because of the number of moving parts (the pics on this page Precision | PINION / P1.18 / DRIVE TECHNOLOGY show the internals pretty well). Everything runs in an oil bath and is completely sealed (like a rohloff). You need to remember that what makes a multi speed chain system inefficient is the way the chains are designed and the tooth profiles that allow shifting. A properly tensioned single speed set up is pretty damn efficient.

I did question using the gearbox as a stressed member and was told it isn't possible. I guess if they made the case stiff/strong enough for that it would make it stupidly heavy. They did seem to suggest that a steel bridge would appear at some point but probably not soon. I know how I would make one quite simply but I would need a press brake/access to one.

Matt


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## Walt (Jan 23, 2004)

I personally think the Rohloff numbers are bogus, just based on subjective feel of pedaling Rohloff equipped bikes, but I don't have any hard numbers to back that up. I know the Hammerschmidt is like riding in molasses in the overdrive setting but that one isn't really intended to be super efficient (and with XX1 out it's irrelevant as well). 

It's always good to remember that gearbox transmissions for bikes have been around for 100+ years and have been worked on by hundreds or thousands of very clever people - and for performance oriented bikes we're still using chain/derailleur drivetrains. 

I think the pinion would rock for a DH sled, personally, or for an urban commuting bike. Looks like that is mostly the market they are aiming for.

As an aside, I wonder how the Type2/clutch derailleurs affect drivetrain efficiency. In theory you don't need much spring tension on the lower cage anymore.

-Walt


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## BenCooper (Feb 25, 2013)

I've found that a lot of the "drag" from a Rohloff is psychosomatic - if you go straight from an almost-silent derailleur to a Rohloff which makes some noise, you automatically think it's draggy. I tried riding with earplugs in, and instantly the effect went away.

I use loads of them - you'd never use one in the TdF, but for 95% of situations they make a lot more sense than an exposed delicate derailleur. As long as you can afford one ;-)


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## 18bikes (Jan 15, 2007)

I think a lot of the percieved drag is also assumed, people *think* it should be draggy so they feel it. I've ridden normal derailleurs, rohloffs and both alfines and can't notice any real difference. I notice more from a change of tyres. I think it is partly due to conditions. If you always ride in the dry and can keep you drivetrain clean and running in good condition then you may notice a difference. Where we are that is virtually impossible. We are surrounded by gritstone that forms a grinding paste that destroys things extremely quickly. I know people who have gone through a set of sintered pads in 1 ride. A gearbox makes a lot of sense in these conditions, even if it's slightly less efficient to start with, if it stays the same then that's a bonus. Plus all the bits that wear won't be exposed to our grinding paste.

It's not for everyone but I think it would make a lot of sense for a lot of people

Matt


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## TacoMan (Apr 18, 2007)

A CR/cog drivetrain once shifted, is only using one CR/cog at each end. With a gearbox, you are also using a CR/cog at each end BUT you are adding in more parts and more friction. 

The gearbox looks like it uses more than one pair of gears, with a typical bevel gear at 90-95% efficiency vs. 98-99% for a sprocket, that is 4-9% extra loss for one reduction or 9-19% loss for two reductions. I sure would not want to have that much loss of power on a bike.

Cars use gearboxs becasue they can shift fast and handle lots of power in a small package. But that is not really needed on a bike since you already have a CR/cog to transfer the power from the crank to the wheel, so having it double as a transmission does not add much more friction to what is already there.


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## 18bikes (Jan 15, 2007)

I'm just speaking from my experience, I don't notice any drag and I know lots of other people who don't. If drag matters to you then gearboxes/hub gears probably aren't for you, if wear/maintenance matter then they probably are for you


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## Penetrator (May 20, 2012)

Please tell me where i can buy pinion bridge?


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## crank1979 (Feb 3, 2006)

Walt said:


> Well, planetary or not, if you're meshing gears and then driving a chain, the efficiency is going to be pretty bad depending on how you lubricate the system and what kind of gears you decide to use. Have they measured it?
> 
> Too bad that they did not design the box as a structurally capable member, that would really simplify building frames with a variety of materials. My guess is that steel/ti is not really on their radar anyway, though, so the aluminum plate/shell/adapter is probably the way it'll be.
> 
> ...


Great looking frame build.

I have bikes with regular derailleur set ups in 1x, 2x and 3x, road Di2 (7970 and 9070), a Rohloff and a Pinion gearbox. I cannot feel any noticeable drag or reduced efficiency in the Pinion gearbox compared to any of the derailleur systems. The gearbox is awesome and completely sealed so my only servicing in two years has been an oil change. The Pinion does not have the same feel as the Rohloff in the reduction gears, it is a consistent feel through the gear range.

My ideal set up would be Di2 shifting for the Pinion gearbox.


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## 18bikes (Jan 15, 2007)

From Pinion


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