Mac's Slant Six Llewellyn Custom Bicycle

The fork rake and the head tube angle are designed to go together and I designed it to have that neutral steering, that’s the main thing that I customised.

Darrell McCulloch from Llewellyn Custom Bicycles and Brian MacLean teamed up to build a steel bike for "Mac's" personal use. How do you even begin to introduce Darrell and Brian with their collective credentials spanning decades at the forefront of Australian cycling development. Darrell's a long term mechanic for the Australian road racing team and respected frame builder. "Mac" as he's known to his mates - you may know him if you live in Brisbane, as a bloke who's expert at customising your bike fit. Aussies racing in Europe as pro's have been lucky to have Mac along the way. The influence of these two Velo Aficionado's is far reaching. Darrell is sought out for his custom bikes and known worldwide for his genius and attention to detail, while Mac is renowned for his talents in helping athletes achieve maximum performance with their bike fit amongst other things, the list is simply out of the scope of this blog.  Joe Cosgrove provided the custom paint job, you won't find a more fastidious frame painter than Joe, also renowned internationally especially for his collaborative work with Darrell. Here's a very special look at Mac's own Llewellyn, a privileged view of a collaboration between two of the most talented leaders in their respective fields. A special thanks to Mac for sharing this on Velo Aficionado.

Here's what Mac had to say about his Llewellyn Bike the Slant Six ...................

Built by Darrell the Slant Six is about six years old and it still has it's original paint job. The bike fit and geometry was the easy part. Getting the traditional paint job to work with the bike and match was the hardest part for a custom bike. Joe Cosgrove did the paint job. I wanted a really simple colour I wanted only a couple of colours.

The bike was designed for my position, you can see the seat is in the middle of the rails, because I've changed my seat position in the last couple of years. I've had a broken pelvis and moved the seat forward. The seat tube angle is 72 degrees. The tubing is a Deda tubeset, but Darrell chooses so many different tubes, it's always a custom set.

I wanted a modern steel race bike and make it as light as you feasibly could. Darrell won't make a bike that's too light because he won't choose really light tubing, in case of falls or 'dings'. In six years that bike's been crashed a few times, hit by a car and it's as good as the day I bought it. I wanted a race bike, with carbon forks because I wanted to make it a little bit lighter and required a little more responsiveness from the carbon forks.

When I built the bike I put a Deda Black Magic carbon fork in but what I found was it wasn't stiff enough and it didn't handle. The Black Magic fork was quite a light one. I wanted to have a look at some different forks. Darrell and I did a little experiment, because he had a variety of forks out at his workshop. We set up a jig where it was a home made test for stiffness. We set it up with a dial gauge indicator on it and we had the forks out of the bike and we'd hang weights on the forks to progressively load them up and test deflection. We did it in both planes both from the frontal plane and also from the side. We conclusively found, and it was no surprise, the lighter the fork the more it 'flexed'. We had a whole series of forks including a fork intended for a tandem. The tandem fork is what's currently in the Slant Six. The tandem fork has a really over-sized and heavy steerer, and also a bit bigger mass through the fork - it was very stiff - the other forks were approximately 350 grams and the tandem fork is about 450 grams, so it's negligible. What we found though was the tandem fork had about double the stiffness compared to the others, that's why I chose that fork.

Because it was an AlphaQ fork, you could buy a fork that had different fork rakes, they don't make them anymore. That fork rake is designed to go with that head angle so the 73 head angle - head tube angle is 73, so with the 45mm fork rake - that's got about 56mm of trail, you get that perfect neutral steering. The definition of neutral steering is the bike responds to both leaning and to handlebar input fairly evenly. A different steering geometry with more trail, say you increase the trail - the bike it responds a lot more to leaning and less to the handlebar input, and as you decrease the trail it responds a lot more to handlebar input.

The fork rake and the head tube angle are designed to go together and I designed it to have that neutral steering, that's the main thing that I customised.

It's a 7800 Dura Ace groupset, it's about six years old and that was standard then. With the Keywin pedals, the thing I like about them is they come in different axle lengths, I chose 'minus six'. Bottom brackets and cranks have got wider and wider so I wanted to get my feet closer into the bottom bracket. That's why I like the Keywin pedals so that I can access the minus 6 mm axles. The bikes have got wider and wider my Ron Cooper bike with the Super Record that's about 6mm on either side narrower, so just to get the same setup as that bike from the eighties, I run the Keywin's with that axle - minus six on the Lllewllyn.

 Mac's custom Llewellyn bike with an Alpha Q carbon fork.

Mac's custom Llewellyn bike with an Alpha Q carbon fork.

Chainrings, it's a home made compact system it was really before you could buy compacts, so I put this together six years ago, the outer chainring is a TA 50 and then I've got the 39, the standard is 39 x 53, a 53 is too big for the sort of riding I'm usually doing and a 34 for me is too small as an inner ring. I got the TA chainrings for the outer ring, I've got a few of those rings, sometimes when I haven't been riding for a while I'll actually put a 48 on, the 48 is a really good chainring. It goes back to those days when people used to tune their gears. I can remember when I first started riding in the seventies, it was really standard to start the season on a 51. Standard then was 52 x 42. The fitter they'd get they'd go to the 52. I reckon it came from the track, people understood their gears, a couple of points on the track made such a great difference. A 48 chainring is such a great chainring, a 48 x 12 is still a big gear - you know it's not enough to race on but it's still enough to ride on though. You've got all these good gears because the ratios are all a bit closer.

Wheels were built by Darrell. They're all black on the front, the nipples. The rear wheel has alternating black and silver nipples. You will notice he has a different type of nipple on the drive side, probably because it holds on a little bit better, although I'm not sure exactly why. The spokes are tied and soldered because it makes the rear wheel a little stiffer and this reduces what they call 'wind up', so when you get on the cranks the wheel responds a little bit more.

I take the seals out of my Dura Ace hubs so that they run a little bit better and adjust the bearings so that they run really smoothly. If you take the seals out you've got to stay on top of them so that the water doesn't get in. The Ambrosio Excellence box rims are an excellent choice, they are really comfortable and with a little bit of flex built in than what you get with deep dish rims. So they're just a great wheel to ride all the time, you can climb on them descend on them, they're an all round versatile wheel for almost anything.

All Lllewellyn bike photographs by Robert Cobcroft

 Custom paint by Joe Cosgrove, Joe is the exclusive bike painter for Lllewellyn bikes

Custom paint by Joe Cosgrove, Joe is the exclusive bike painter for Lllewellyn bikes

 The Slant Six Lllewellyn custom bike

The Slant Six Lllewellyn custom bike

 Dura Ace 7800 Shimano front brake

Dura Ace 7800 Shimano front brake

 Alpha Q carbon fork

Alpha Q carbon fork

 Hand cut heart seat stay bridge a signature detail on many Llewellyn bikes

Hand cut heart seat stay bridge a signature detail on many Llewellyn bikes

 Traditional paint scheme from the Joe Cosgrove Cycle Design solid colour range

Traditional paint scheme from the Joe Cosgrove Cycle Design solid colour range

 Tried and tested old school box rim

Tried and tested old school box rim

 Dura Ace 7800 Shimano crankset with Keywin pedals

Dura Ace 7800 Shimano crankset with Keywin pedals

 Dura Ace 7800 Shimano

Dura Ace 7800 Shimano

 Tied and soldered spokes

Tied and soldered spokes

 Dura Ace 7800 Shimano rear derailleur

Dura Ace 7800 Shimano rear derailleur

 Ritchey WCS stem

Ritchey WCS stem

 Hand polished stainless steel Lllewellyn bike head badge

Hand polished stainless steel Lllewellyn bike head badge

 Darrell McCulloch's distinctive Lllewellyn Bike head badge

Darrell McCulloch's distinctive Lllewellyn Bike head badge

 Llewellyn bike models have changed over the years. Today Darrell doesn't build using the Slant 6 name

Llewellyn bike models have changed over the years. Today Darrell doesn't build using the Slant 6 name

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