Building my own carbon mountain bike

I’ve been toying with idea of making my own carbon mountain bike for nearly a year now and finally committed to it back in April by ordering the carbon fibre and resins.  This blog contains the steps I followed to build my own carbon 29er single speed bike. 

The concept

I have thought about building a bike for a while but only wanted to do so if I had a unique design. So I started by placing the key geometry points of a bike onto paper.  I wasn’t interested in this stage in designing the geometry, so I simply took the geometry of my Ventana El Commandante, as I really enjoy riding this bike and I know the geometry works well for me. Having the key points: head tube, bottom bracket, drop outs and top of seat tube located on paper allowed me to sketch frame designs linking all of these points together.  I quickly came to the likings of the simplicity of a combine top/down tube and only enlarged chain stays to connect the rear dropouts.  This gave the appearance of a sleek clean bike and would also be easy to manufacture using carbon fibre as there are less tubes and joints to deal with. Playing around with different configurations I finally settled on a design.  

The construction concept

Now I need to know how to make my own bike.  Luckily I had all ready thought about this before designing the bike. My fabrication plan consists of making a polystyrene core of the frame that would allow me lay the carbon fibre over it, as per a standard mould-less wet layup. For the key features of: bottom bracket tube, head tube and seat tube, which had to accurate internal diameters, I decided I would make these tubes from carbon to the right size by using aluminium mandrels, as moulds to wrap the carbon fibre around. Collin a friend of mine machined three mandrels to the sizes I needed for my tubes (head tube upper and lower limits ID = 49.62, 49.57mm; bottom bracket upper and lower limits ID = 54.0, 53.8mm; and seat tube upper and lower limits ID = 27.25, 27.10). I had the luxury of having the rear drop outs profile cut on a CNC router, cheers to Bill for this. The LH dropout also had the addition of a brake mount holes machined into it to allow the brake as the brake needs to go somewhere.  This saved the hassle of having to add mounts for the rear disc brake onto the frame.  Much better to combined tight tolerance items together so they can be located from a single point, such as the dropout centre. The other major issue to address in making a bike is to keep everything aligned and square, else your bike will feel weird to ride and will not ride in a straight line and favour turning to one side, which could be good for a Nascar style bike. 

Building the jig

Again I exploited the use of the CNC router that my work has.  I designed up an interlocking jig on Solidworks and then produced G code from the models using Rino CAM. The CNC router then did the rest accurately cutting out all the jig items.  

Sourcing the materials

Next step in the project is to get all of my materials for my frame.

• Resin,  http://www.adhesivetechnologies.co.nz/, these guys are really helpful at providing the right resins for the right job.  I used ARD270 resin and ADH28 hardener.
• I ordered the carbon firbre from High Modulus located in Auckland. These guys were also very helpful, in providing me information of what fibres to use and even gave me an indication of how much fibre to use.
• Polystyrene for the core I got from Ploycut Christchurch. These guys cut up polystyrene blocks for insulation, signage and other polystyrene foam products.
• Aluminium for drop outs were just off cuts from work.   
• MDF, screws, threads, etc were all purchased from a hard ware store. 

Let the building commence

I choose to make the bottom bracket tube first as I was going to use a Bushnell bottom bracket http://www.bushnelltandems.com/  ebb (eccentric bottom bracket) to tension my chain.  The Bushnell bottom bracket expands its diameter as one tightens the adjusting screw. The ebb locates in the desired place by friction force created by high compression force of the ebb expanding into the bottom bracket tube.  So using the ebb, which I have from my Ventana bike, I could test the strength and stiffness of the carbon bottom bracket tube by inserting the ebb into the bottom bracket and tightening the adjuster screw on the ebb.  I tightened the screw until it went as tight as I could get it using a standard size 4mm allen key. I was pleased with the result as the ebb was securely locked into the bottom tube and the tube remained rigidly intact.  To make the bottom bracket tube work it must have a high hoop stiffness to ensure that the expanding ebb will locate in place.    Knowing that the ebb is mostly under hoop stress, uni direction carbon fibre was used wrapped around the bottom bracket mandrel with most of the fibres aligned circumferential. Using 200g/m^2 uni carbon fibre with the following stacking sequence. Once the carbon was wrapped around the mandrel a layer of peel ply and breather material was also wrapped around. Vacuum bagging was used to suck out the air and apply atmospheric pressure to tightly hold the carbon fibre in place during curing. 

The seat and head tubes were made in a similar way as per the bottom bracket tube but had different stacking sequences that I determined would be adequate for these tubes. 

Shaping the foam core

This was one of the messy but equally one of the funnest tasks in the project. I began with a block of polystyrene foam and drew the side profile of my bike on it. I then cut out the shape using a wood saw and sanded the polystyrene away using 80 and 150 grit sand paper.  Cutting and sanding polystyrene is a quite a rapid process as it is very easy to cut.  I took great care in making sure I didn’t cut too much away.  Over the space of a few hours spread across a few evenings I had a nice looking foam core of my bike.    I used the jig as a guide to help make sure I was sanding the foam away from the correct places.

The first layers

I put the tubes and drop outs into their respective jigs and positioned the foam core. After double checking the alignments I was ready to begin adding the carbon fibre.  The first layers I put on wrapped around the bottom bracket from the down tube. I then put additional layers from the bottom of down tube to the beginning of the rear stays.

Next session I wrapped uni directional fibres around the head tube, seat tube and rear faces of the seat and down tube, and also along the full length of the underside of the down tube.

Third session, concentrated on the rear stays, here I put uni-directional fibre across the top and bottom of the stays and wrapped the ends of the stays tightly with carbon yarn. To prevent any aluminium carbon corrosion I put a layer of fibre glass around the aluminium to insulate the aluminium from the carbon. I also placed carbon unis along the top side of the downtube and seat tubes. 

Fourth session this was a tricky one due to having to place carbon from underneath, luckily I had a helping hand for this. Here I placed carbon unis along the sides of all the tubes for lateral bending stiffness.  Before I placed the layers I added a plastic tube to allow for internal cable routing for the rear brake.   Again once all fibre was in place I wrapped the bike in PVC tape to keep everything tightly in place.

The remanding sessions, up to 8 or 10, were spent on adding layers of carbon twill and additional unis.  Once I thought there were enough layers on the frame and it felt stiff enough from standing on it I began assembling the bike. I pinched all of the components, forks, stream, handle bars, wheels etc from my Ventana bike. The only difficult arose when I tried to spin the cranks and noticed that the drive side crank rubbed on the chain stay. This was soon fixed with a few spacer rings on the drive side of the bottom bracket to space out the drive side crank.    

Look at the carbon hotness

Taking it for a spin up and down the drive was really exciting and rewarding.  The bike held up and didn't explode into a million bits of sharp carbon fibre splinters.  This gave me the confidence that I must be on the right path, so I painted my bike with some old yellow paint, Sun Yellow, left over from Canadian canoe.  

Sun Yellow what was I thinking....

With the bike painted it was time for its maiden voyage.  Up Worsleys, down the Flying Nun and across the Traverse and back down Huntsbury. The bike held up and felt really stiff in the back end.  

Just been out riding it tonight and can happily report that the bike can with stand the abuse of Victora Park.

Oh for those that are interested the carbon frame weighs in at 2.1kg, a little on the porky side.

The infamous KFC Double Down

Ever since my flat mate Tim returned from the states a year ago telling a tale of a legendary KFC burger which uses chicken breasts instead of buns; I was left wondering what would such a creation taste like? Would my taste buds ever get to indulge in the glory of eating one of these burgers known as the ‘double down’.

A little more than a month ago KFC made an announcement that would change the NZ fast food industry forever: KFC were introducing the double down into their finger licking menu.  This created an up roar with NZ’s politically correct health critics, but their boycotting message of discouraging the population of consuming such a hazardous food item has only fuelled the nation’s desire to feast on this greasy beast of a burger.  Well this only left me salivating in anticipation. 

The month of April flew by and the first of May came, but where was the double burger? Had our beloved PC health critics won the battle of the ‘double down’.  NO! I just had incorrectly convinced myself of the release date.  I had to count down another 11 long days, much like the wait for Christmas. As the release date neared I mentioned to my flatmates the concept of the ‘double double down’. This would involve eating two double downs in one seating, surely this would double the thrill. I'm sure I could handle this challenge as I known to fight/eat a few classes above my weight.  

  Finally the day arrived, an evening mountain bike ride burned away what was left in my tummy.  Down to the Cashmere dirty bird (aka KFC) and the wait continued in the endless line of double fans.  I surprised Nic when I ordered the large double down combo, but the extra double down I ordered was expected, as I’m not one to back down from challenge, especially one that I put forward.  We finally received our orders and race back home at the speed limit and lined up the burgers ready for devouring.      

Double down group shot

The double double line up. 

Nic finishes swallowing a satisfying bite of the Zinger double down.

Tim the double down veteran gets stuck into his first down under version  of the  double down.

My first bite into the original recipe double down hit the spot like Joe DiMaggio hitting a home run in the final of a World Series.  The crispy bacon strips teased the tasted buds on their way down my esophagus, the cheesy chicken breast also slid down with ease due to the greasy lubrication of the double down.  With a few more bites the beast was done.  Satisfied and left craving for more I unwrapped the second of my double downs. 

Me beginning the Zinger double down.

This one was the Zinger double down, which is chicken breast coated in the mouth watering hot and spicy recipe batter.  As the typical teenage girl would say “OMG” is what I thought as I took my first bite. Wow this made my mouth climax. A few more bites  and I had completed the one of life’s greatest challenges the KFC double double down. 

I highly recommend this bun-less wonder to everyone, vegetarians and diabetics included life’s too short not experience it.  To sum it up I would like to quote my favourite inventor Leonardo Da Vinci “Simplicity is the Ultimate Sophistication”.  Wow didn’t think I would ever say that about a burger, especially one produced by KFC.        

12/10/2010 Friday Day 23 Kathmandu to NZ via Singapore

The taxi ride to Kathmandu airport.

Mt Everst and Mt Lhotse below the wing tip

Revenge is best served on sushi trains

11/10/2010 Thursday Day 22 Kathmandu

Woke up and started reading my book, whilst Ollie got bored and went to get some money and came back with warm apple strudels, yummy. I ate mine still in bed finishing of the chapter that I was on. Once I was up we began today’s adventure by walking west through the streets of Kathmandu in search of the famous monkey temple.

On the way we passed through streets that were filthier than rubbish tips back in NZ, the filthy grim was unimaginable. We watched people simply empty sacks of rubbish next to river.

We ended up crossing the polluted river on a bamboo bridge spanning some 10m. We continued on the path of filth until we reached a main road, we went west until the road began to climb, too far so we headed south towards the hill with the fancy temple on top.  Little did we know this was the monkey temple. We asked for directions from an armed police officer who had an old Chinese assault rifle that looked as if would shoot as far as you could throw it.  We realized that we were on the right track when we saw locals crowd around tourists trying to sell them all sorts of nic nacs.

It only took a few steps up the hill to spot our first monkey busily feeding away on raw rice. I tried to get Ollie to sit close to the monkey for a photo, but the monkey was quite protective of rice dish, and gracefully showed his teeth when Ollie neared. We watched the monkeys for an hour and headed back to the hotel. It took a while to find the hotel again in the crowded streets.

We spent the rest of the afternoon cleaning our bikes to perfection for the NZ customs. I ended up needing a mechanic for an enlarged allen key as my pedals wouldn’t come off. A motorbike repair shop helped sort this out. On the way there I got hit by a car in the back of the leg, but only at low speed, I didn’t even bother to turn around.     

Once we had the bikes packed we treated ourselves to some more backed goods then headed back to our hotel for some R and R until hunger brewed. We ended up having a set Tibetan menu which was our first dish we couldn’t finish off. I enjoyed an Everest beer whilst thinking about the adventures of the past few weeks. I was glad to be heading back to NZ tomorrow, but somewhat sad that our Himalayan holiday was at an end.    

10/10/2010 Thursday Day 21 Nagarkot to Kathmandu

Explosive diarrhoea this morning and again before breakfast, this had all the makings for a shitty day. Our expected views of the Himalayas also failed to show themselves through the dense haze. I enjoyed a good bowl of porridge for breakfast, and was climbing the four stories back to our room to get the last of the gear and began to feel queasy, I wasn’t sure from which end it was going to come from!

A few deep breaths and I began to feel better, we got on the bikes rode 300m and went the work way this was going to be one of those days.  As Ollie was adamant we were again on the wrong path we ended up riding back past the hotel we were in to an intersection to get our bearings. We then rode past our hotel again as we were on the correct path. We followed the track for a while, things were looking good to get us to Jinuv, but we mistakenly took a left which lead us in another half hour dead end.

We finally got to Jinuv and where a local man guy pointed us in the wrong direction, which we unknowing followed for yet another 30 minute detour.

This track was at first quite nice single track but then just vanished in the midst of rice terraces. No good back we go.  We finally got on the correct track some 3 hours after leaving Nagarkot.

An hour later we were at Chispani having lunch and cokes. We bought some permits and headed on, this leg of the 4wd track had not been used for quite some time and was covered in plenty of growth.  I felt like Indiana Jones but much cooler smashing through the dense vegetation on the bike. After two hours we came on top of ridge, as this made no sense and we were totally sick of the continued back tracking we used the compass and the watch to confirm that we were facing south and south we went back to the comforts of Kathmandu, somewhere in the distant valley below.  We descended through the nice jungle and broke out in the mess and filth of the outskirts of Kathmandu. We rode back into the chaos and finally got back to the hotel.

Of to the ‘Rum Doodles 40000 and ½ ft’ bar and restaurant for pizzas and lassis, yummy.  This restaurant is one of the best known restaurants in Kathmandu as the all Everest climbers have their names signed on small plaques hanging all over the restaurant walls. 

9/10/2010 Wednesday Day 20 Kathmandu to Nagarkot

Woke up this morning tried and wanting to go back to sleep, but the urge to empty the bowels was much stronger.  Diarrhoea again! Oh well off to breakfast. We ate our cooked breakfasts at the top of a hotel overlooking the Thamel skyline. We finished our breakfast and headed back to our hotel, Ollie went in search of an ATM machine I went and paid for our hotel room and found myself getting started in Ollie’s book “Running with Scissors”. An hour later Ollie finally found his way back to the Hotel after paying someone to guide him.

We got on our bikes minus the dry bags as we were going to travel light for two days riding around the Kathmandu valley. We headed south of Thamel and ended up in the south of Patan in the southern part of Kathmandu, another wrong right turn lead us into the south eastern foot hills of the Kathmandu heading towards Godawari. We looked at the map realized our mistake and headed back up north. We quickly got back on route and onto the main drag, which contained four lanes of chaos. We noticed a few flattened dogs on the road and hoped that wouldn’t happen to us.   

Riding up to Nagagrkot

We continued towards Bhaktapur and once there we found a way in the general direction of Nagarkot. I soon felt tired and struggled with any descent pace. Ollie powered off ahead, but routinely came back to check on my progress. We ended up riding the ridge route up to Nagarkot view tower. We enjoyed a coke and mountain dew, before viewing the tower. A lot of local couples were up at tower most likely taking their girl friends for a romantic afternoon outing to the rubbish littered hill top. It seems that the higher class produces a lot of the litter as they don’t show any respect to their environment. We descended down the sealed road towards Nararkot almost took out a mob of youth walking up the road.

We checked out the club Himalaya hotel but found it was a little out of our price range at $100US a night. We then ended up getting a penthouse suite at another Hotel more in our price range at the Himalayan Heart Hotel. We spent the rest of the afternoon watching BBC world, snoozing and showering. We then ended the day with a steak dinner.    

8/10/2010 Tuesday Day 19 Pokhara to Kathmandu

 No breakfast for us this morning, up at 6:30 packing our bags to catch the bus back to Kathmandu. We did however stop by the German bakery to buy some snacks for the journey. As I was purchasing the Danish pattie, cheese and chocolate croissants I noticed a roach or beetle walking over some of the produce, oh well what else can you expect.

We biked around to what we thought was the bus park and waited patiently eating some of the baking. It was nearing 7:30 and the bus guy yesterday told us to be there by 7:00, but there was no sign of our bus only passing local government blue and white buses. I asked a passerby where the bus park was and he said “down there, must go quickly”, so off we went and sure enough we just got there with enough time to get the bikes on the roof, tie them down, and away we went. Ollie and I initial had the back right hand side to ourselves whilst two Asian girls had the other side, luckily they got off after only a few hours and then I had the whole back row to myself as Ollie move forward a row.

Ollie's attempt at drinking from his bottle left him pretty wet, due to the bumpy road. 

Our last view of the Annapuranas.

The bus ride was hot, noisy and extremely rough, but it did allow one to get a good grasp of rural Nepal, without having to sweat and pant as if you were on a bike. The bus stopped at the bottom of our detour hill before Dumre for breakfast. We had some Sprite, as I was still avoiding coke due to my binge a few days earlier.   We again nearly missed our bus as they said they would give us 40 minutes, but seemed to roll away after 30minutes.  

Shortly after we were in a traffic jam outside Mugling. This was due to only 1 vehicle being allowed on the suspension bridge at a time. Once through that we drove on until 1pm where the bus stopped for lunch 67km away from Kathmandu. We only bought some biscuits and Sprite as we thought we could have lunch once back in Kathmandu. An hour later we were stuck in gridlock at the bottom of the hill that leads into Kathmandu valley. About 3 hours later we were finally over the hill but traffic was barely moving. So we got our bits together, explained to the driver that we getting off, even though he wasn’t going stop  more than he had too, ok by us. Next halt we got out, I climb up on the roof and began untying the bikes and dry bags. I passed the bikes down to Ollie as he ran along next to the bus. 

The long chain of traffic slowly creeping up the hill

With bikes down, lights on, we were on our way weaving the evening traffic. This made for some exciting riding in the heavy chaotic traffic with both our lights fading to blue dots. We had to watch out for monster potholes and vehicles coming from all directions. We stuck together in our dual player video game of dodging allsorts with only 1 life remaining.   

Surprisingly or simply just our awesome navigation skills got us back to Thamel quickly, only once back in Thamel did we back track ourselves only once and with simplest ease we found our Hotel as Ollie simply saw it as we rode by heading in the general direction of it.

We checked in, dropped of our gear and like our ancestors from millennia ago went in search of food. The ‘Cozy Restaurant’ was our choice of the evening, with burgers and momos and double banana lassi. The lassis were amazing still thinking about them now, maybe for breakfast I’ll have one or two.