# Twins, project bike constructed



## Eric Malcolm (Dec 18, 2011)

Hi. I have been doing this project for some time now, mostly as a time filler at my workplace/lunch break. It is constructed mostly from non standard bike tubing, scraps and clothed with components from an old unused bike that got passed on to me. I have an interest in old bikes, particularly designs that I feel have potential to look radical with a modern twist. My own cycling background is in road racing, so the themes I tend to style to reflect in the over-all finished bike. My current cycle usage is in the area known as Gravel grinding, and in particular, short distance daily commute over cycle trails around where I live, so this bike is sort of a 'sprint bike' of that genre. The base bike that I have adapted this overall build from comes from a HUMBER cross tubed frame dating back to 1900, and a bike that Alan Crisp showed sometime ago in this forum.









The bike is not fully finished, I have been testing it over a period of weeks now. Sorting out what part of the structure is contributing to the 'feel' that I am looking for, and there is so much unconventional in this frame to warrant taking the time to work through before I paint it.
It is compared to the E-stay as my 'control' bike and all the connection points are the same, I lowered the BB height to take into account the shorter crank used 172.5 vrs 180mm. The Chainstays are 20mm shorter at 385mm, otherwise these 2 bikes are identical twins. Amazing how visual perception can trick you though.... Both bikes weigh in together at just under 10kg (22lb)









I probably have 100 hrs in this frame in actual tinkering and constructing, but as a hobby builder, this means nothing to me, the joy has been in thinking it all out.









Comments made locally focus on the Chainstays, so I will explain that the original Humber had 2 C/S on the drive side and 1 on the non-drive side. I thought about uneven length instead and this is proving to work well and it looks initially challenging, as a ride, I like what is happening from this configuration, very narrow too, using 12.7mm tube. The fitted seat tube does what is supposed to do, I have not made a decision on this style yet.









The rear brake has been connected, no gears yet, I will set them up after paint and are internal.

You may ask about the Handlebars, I need to incline them a little as they splay outwards, which is normal when they are the right way around.

Also, the short C/S was used as I could not figure out a way to do a bridge that I could get my fingers in to clean the bike - got to be practical. This bike will be a nightmare task to keep clean.

Enjoy
Eric


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## Walt (Jan 23, 2004)

My hat off to you, Eric - this is a glorious piece of work!

There was a fellow making chainstays this way in the states at some point recently but I can't recall the name. It looked like a crazy amount of work. But it definitely fits with the theme of the bike here!

Can we get some shots of the bar/stem area? Pretty please?

FWIW, the lack of chainstay bridge will not hurt you in any way. 

-Walt


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## jgerhardt (Aug 31, 2009)

I keep clicking to get bigger images...
Do you have a link to gallery so I can get some detail shots?
Beautiful frame!


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## Clockwork Bikes (Jun 17, 2006)

I second that. Get a free Flickr account.



jgerhardt said:


> I keep clicking to get bigger images...
> Do you have a link to gallery so I can get some detail shots?
> Beautiful frame!


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## Drew Diller (Jan 4, 2010)

Oh my...


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## dr.welby (Jan 6, 2004)

Walt said:


> There was a fellow making chainstays this way in the states at some point recently but I can't recall the name.


Probably thinking of Ahearne:



Double Chain Stay by Ahearne Cycles, on Flickr


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## G-reg (Jan 12, 2004)

Clockwork Bikes said:


> I second that. Get a free Flickr account.


Yup, need bigger pics to properly geek out.


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## Eric Malcolm (Dec 18, 2011)

Walt, the pictures of the Head Tube area as it developed:












































I have used a bi-lam method in some areas, they double up as gussets, and give me more surface area to braze with. The D/T wall thickness is only 0.5mm, so I needed a bit more meat, in other areas, 0.9 tube is used, so they attach directly, and where the load reduces and a large surface area is available, I have simply directly filleted the joint. The upper H/T jointing is done this way, it all just manages to fit onto the 44mm H/T.

Dr Welby,

Thankyou for the illustrated bridges, just what I wanted to avoid.....I'll get a photo of mine (tire and chainwheels) and post it later.

Eric


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## Eric Malcolm (Dec 18, 2011)

*Seat/Cross tube detail*





































I have used a Nova 35mm 29'er D/T for a Seat tube. I wanted the bend and it was 750mm long which was perfect to get my needed seat height.
It suited the geometric style of the frame, but is butted, and I felt that I should Gusset this area as it is in the area where it transitions from 0.6 through to 0.9mm. I took the liberty to style it a bit, 'cause its a long way up to the saddle from the S/Stay joinery and gives anyone following a bit more to look at than my 'knarly' legs....

Eric


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## Eric Malcolm (Dec 18, 2011)

*Twin uneven length Chainstays - the process*

When I began to put the rear triangle together, I taped my tubes into position to have a look at the overall effect and check sizing. When I drew up drawings, I had a side view and a top view. What completely threw me and had my head struggling to come to terms with was the 3D angle as shown in these 2 pictures, I was not prepared for the 2 tubes appearing in parallel. It just looked terrible.
















There was none of the smooth visual flow as seen here in the side view.









So I did a little bending of the lower stay.
















Which yielded a very pleasant flare, which was how I originally imagined it to look like.
















Eric


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## Eric Malcolm (Dec 18, 2011)

*Twin Chainstays, some thoughts, the performance, does it work*

With this build, comes lots of questions, so now having spent more time on it and constantly testing new ideas, I submit these conclusions.

The rear drop-outs are cut from 6mm plate. Cross drilled and a 3/8" x .035" tube fitted. A flanged M10 Drop-in masonry anchor is sacrificed and over-sleeves the tube to give me the Drop-out.









The overall attachment is brazed, filed and is very strong. The drop-outs weigh 180grams.









The left-hand side does nor suit Disc Brake attachment - more on that later.









The BB area gives 55mm width, good clearance for the 35mm tire.
The inner chain-wheel clears the chain-stays by only 1.5mm. Now this is where other factors take effect. I have a 34.9mm seat tube and 2 x 22.2mm down tubes attached to the BB shell, so there is no rotation of the BB. The 12.7 x .9mm Stays must stay firm and not flex, or the chain-wheel will rub the stays. There is no rubbing taking place. Also, this bike tracks rigidly from the rear, I am getting excellent drive out of the drive train.









So, this is how I conclude the experiment. YaHoo!!!

Right, serious applications that could work very well. Humber, who followed this path in the early 1900's described this feature of their bikes as suitable as heavy duty compared to the conventional chain-stay. They used it only on the chain side and used a conventional stay on the left, leaving a modern interpretation able to use disc brakes. Lately, there has been a lot of Chain-stay manipulation taking place, and I suggest that this is an option to add to the list. It has the advantage of offering easy tube bending to get around tight spaces, though setting up to weld takes a little longer. Depending on whether you use unequal or co-join onto a drop-out, there is merit in this option.

Eric


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## TrailMaker (Sep 16, 2007)

Funny;

...How one aspect of a design can slap you across the face like the original stay layout did. How can two tubes that are never parallel look... parallel? Short of a full blown 3D CAD program, there's just never any knowing until you see it in front of you in the flesh. Your solution was simple, and in the end brilliant. The stays look almost impossibly spindly on first glance. Bird-like and fragile, yet the amalgam is anything but. It all has an elegant, industrial, architectural sophistication about it that is very intriguing. 

That it actually works is a nice bonus, of course!


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## Eric Malcolm (Dec 18, 2011)

Some pictures of the finished Bike. The ride that the forks give is really supple, the bike tracks well, fork flexes a little, but not enough to be concerned about on gravel roads where it excels. The whole frame is pleasantly communicative with a nice mix of rigidity and comfort for a bike of this type. Its seems strange to be riding along with a bike well below you, hands attached to stalks. I have had recent opportunities to ride in a Pace line with road racers on a Sunday morning ride which covered an especially bad piece of asphalt surface where we all got a jarring through the bikes. Mine did not suffer anywhere as much as the Alloy framed/Carbon fork and full Carbon bikes so I have to feel pretty happy with this build.
















All the jointing came up well after Powder Coating, though it has a second coat due to not getting full coverage in some hard to get at tight spots that this frame presented for the powder coater.
















Just enough room for dry pack riding.









I have been asked to make another, so, I'll be busy for a wee while. The ultimate compliment.

Eric


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## todwil (Feb 1, 2007)

B!TCHEN.......JUST B!tchen!!!!!!!


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## jgrano (Dec 5, 2011)

Love the build.


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## Drew Diller (Jan 4, 2010)

(I might have come back to look at this thread several times now.)

(Just saying.)


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## WA-CO (Nov 23, 2013)

I spend quite a bit of time looking at bikes and bike building. I would like to think I have a pretty decent eye, at least for the aesthetic. I think this is really cool and very novel, especially, the prolific use of dual (double) tubing, which I find quite neat. 

Great work!


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## dump (Nov 14, 2005)

Wow, that's quite a lot of intricate work - congrats.

Would you mind explaining/showing your jig? I haven't seen something like that before. It looks like a combination of a production part mixed with some custom fab. Also, how did you do the alignment? Thanks.


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## Eric Malcolm (Dec 18, 2011)

dump said:


> Wow, that's quite a lot of intricate work - congrats.
> 
> Would you mind explaining/showing your jig? I haven't seen something like that before. It looks like a combination of a production part mixed with some custom fab. Also, how did you do the alignment? Thanks.


You can find a wonderful array of jigs in 'Your home made jigs' thread, about halfway down the index to this forum (present day).

It is a converted Diamond drilling rig. Worn out and twice around the clock, I heard of it being dumped so I asked if I could have it. It came with 2 Columns, and I was able to cobble it together sufficiently to build a frame off it. I have no problem doing the main triangle of a frame, I need to tidy up the rear axle positioning a little better than I have it, I can also build the fork off it as well. The trolley has proved very versatile in doing fork/frame tasks.

Eric


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## Eric Malcolm (Dec 18, 2011)

I'm not sure how to explain the responses that I have received when I am out riding this bike. I built it with the thought of the engineering design challenge being utmost, how it looked was secondary, the historical base combined with the 'Hot-rodding' of a 1900 original is novel, but I did not intend it to receive the attention that I have experienced.
I have been escorted to the kerb to be asked about the bike, cars slow down and the occupants give it the look over and I receive a thumbs up. Stopped at traffic lights, there have been conversations before the green appears, Motorcyclists give it a double take as they overtake me, etc. Funny thing is, it appeals to non-cyclists far more than dedicated riders. I guess that would be due to its non-complying UCI status for the competitive types, but my wife likes it, and that means a lot!!

Eric


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## Clockwork Bikes (Jun 17, 2006)

Eric Malcolm said:


> I'm not sure how to explain the responses that I have received when I am out riding this bike. I built it with the thought of the engineering design challenge being utmost, how it looked was secondary, the historical base combined with the 'Hot-rodding' of a 1900 original is novel, but I did not intend it to receive the attention that I have experienced.
> I have been escorted to the kerb to be asked about the bike, cars slow down and the occupants give it the look over and I receive a thumbs up. Stopped at traffic lights, there have been conversations before the green appears, Motorcyclists give it a double take as they overtake me, etc. Funny thing is, it appeals to non-cyclists far more than dedicated riders. I guess that would be due to its non-complying UCI status for the competitive types, but my wife likes it, and that means a lot!!
> 
> Eric


I get the same thing on my penny farthing. It's like being in a one man parade.


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## TrailMaker (Sep 16, 2007)

Hey;

Average biker types - having their prejudices gained from herd experience, not from their own study or sensibility - assume it is not a viable design because it is different. Those not in the know are blissfully ignorant of such biases, and like it for the same reason. Those with an eye for structure - from either camp - would certainly be intrigued.

I've enjoyed this project. What's next?


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## Eric Malcolm (Dec 18, 2011)

What's next? A more conventional version of the above bike, flat bars, single down tube, no sleeving, well, not like the above bike, but otherwise same outline. 

Just waiting for a couple of machined parts before I get going. I'll add it to this post as I go along. It is for a family member so I've got to get busy. A late Xmas present, no pressure....

Eric


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## mickuk (Jul 6, 2007)

Can't believe I missed this - great work!

I really like working with multiple smaller tubes, and this takes it to a rather fabulous extreme.

Someone I know made a great replica of a Bugatti frame which is even crazier - scroll down to the bottom of this link:-

Our Work - Poetry In Motion Cycles


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## Eric Malcolm (Dec 18, 2011)

That Bugatti is interesting. Did not know about that one. The forks are remarkably similar to the Humber Duplex, though straight. Not sure if it would be supple in its ride, any feedback? Has this frame been built up and ridden? The 3/8" chainstays are part of my original design but I upped this to 1/2" and I know that these are more than adequate, but how do 3/8" flex? I can Laterally flex the fork of my bike, so I wonder how the rear performs here. (just Geeks talk for those following...)

Nice build and thanks for sharing.

Eric


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## shoo (Nov 11, 2008)

Very impressive execution of your design. Looks like a fast and fun bike to ride. 

It would be enjoyable and enlightening to spend a lunch break with you.


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## Eric Malcolm (Dec 18, 2011)

*Twin/Cross Tubed Frame: Mark 2*

OK, so I have working on my second edition of this frame design style.









The seat tube is made from 2 Tubes, using a NOVA Cycles DT 35mm Bent, and a Columbus BMX external butt ST of 26.8mm Size. This required a reducer.









The completed item. This frame will use a carbon Seat Post.









The Chain Stays have been co-joined, rather than using the earlier method. No particular reason for this, just trying out a variation - I never do identical repeat frames. Each one is unique. These are 405mm long, and I am not going to use a bridge. They are quite stiff, since only half the length is free to flex.

Eric


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## TrailMaker (Sep 16, 2007)

Ha;

More artwork, My Friend!


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## Eric Malcolm (Dec 18, 2011)

*Seat Tube with Style*

Ok, here we are with a nearly completed frame. I ran out of gas to cook on the Front Derailleur boss, so I cleaned the frame up a bit.









Something strange going on here, spot the difference?









Interesting side note, the Cross Tubes are Columbus Life seat stays. When I ordered these, I thought they were fully round, but when they were unpacked, I found that they are part tear-dropped in profile. In correct usage, they would fit between drop-out and brake bridge on a road bike. Here, since I wanted to soften the 'look' of this bike, I used a tear-dropped profile DT, I was able to neatly fit this apparent set-back into a very neat fit within the main triangle.









Ohhhhh, where did the Seat tube go!!!!









Neat eh. Cool as.

I am using the Carbon Seat Post as a structural member, a colour brake, reducing duplication of material, and, I always wanted to do this.
I like variations around the seat joinery. You can make your biggest signature statement about your bike in this area. I have fitted the seat post in for a look, but I'll tease you for awhile, and keep you in suspense.

Eric


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## TrailMaker (Sep 16, 2007)

Now...

That right there is cool, dood!

I saw the lower ST clamp straight off, but did not register its purpose until the last pics.


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## Drew Diller (Jan 4, 2010)

Love it.


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## briderdt (Dec 14, 2012)

Sweet! Can't wait to see the fully-built bike.


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## joeadnan (Oct 21, 2003)

Any updates, Eric?


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## Eric Malcolm (Dec 18, 2011)

I've had a wee break away, but I am presently back onto this build so will hopefully post something in a week or two.

Eric


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## Eric Malcolm (Dec 18, 2011)

*Pre-assembled, test ride, now off to the Powder Coater*
















The 2 Bikes featured in this thread differ in size, and in the Down Tubes used. The twin DT bike is very rigid laterally, it is an amazing bike to ride in that it is both speed capable, but stiff. It is the only bike I have ridden that communicates the steering to the saddle and I can steer this bike off the nose of the saddle, otherwise, it behaves like a bike of the rigid diamond frame genre. This smaller framed bike is setup like a roadster and will see asphalt and gravel cycle ways. It also has a standard bike feel, but the DT on this one allows for the 'natural' rhythm of the peddle stroke to take place.

Will post a final finished Picture when we have a colour and it is completely assembled.

Eric


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## Eric Malcolm (Dec 18, 2011)

*Well, here we are, at the end of this project series*

























I have a daughter who is very pleased with her new bike.

The frame has a steep 76* ST angle. 520 EFT, 70.5* HT angle and 67mm of trail. The front centre came out at 630mm, which I am really happy with. The bike retains a really nice stability/manoeuvrability ratio for a short rider, bike is light at 9.5kg (21lb) for a roadster style bike and runs on the gravel superbly.

Not sure what I will move onto now, I have a lot of ideas, sketches and plans, but no fixed direction just yet. I am firmly placed in the Gravel genre these days, but I may be a little ahead of my time, so will apply some patience and see what comes next.

Thanks for following and hope this series inspires you.

Happy Building.

Eric


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## SlowSSer (Dec 19, 2003)

amazing work. i love the out of the box thinking.


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