Plycycle Mk2 - Mostly finished.

With shaping done, varnish followed and then as soon as it had cured the final build. The main components are from a donor bike, with alfine 8 speed hub gear, and shimano disc brakes. The forks I had found were quite straight and gave a very twitch ride so we used the forks from the donor bike as they had a good forward reach which mellowed the steering. The twitchy steering was also a result of me making the head tube angle too steep. It was more shallow but I had a brain fart one day and changed it for no good reason, or at least not that I can remember. You live and learn.

Only thing to do are to properly fix the rear brake cable currently held with cable ties.

The reinforcement.

A close up video look at the new reinforcement pieces. 

Resurrection

So when I walked away from building this bike in 2016 I had cut two chunks out of the frame where it needed reinforcement but then hung the frame up in my garage and left it there. Cut to 2019and my son Cuan needed a new bike. He asked if we could finish the plycycle Mk2.

The first thing we did was to tidy up the rather bad cuts I had made in the frame and then we set about fitting the new cross ply pieces. The reinforcement plan was simply to resin in fresh plywood at 90 degrees to the existing frame grain. The weakness being that the frame had too much flex and rode like a jelly. 

The top tube line could have straight ply plank fitted so we opted Fort Worth pieces of 14mm ply glued straight in with a filament resin. The down tube is curved so we went for three layers of 8mm ply bent and glued with the same resin.

Before we went any further down the build we put all of the components onto the frame to see if it was even worth continuing. 

The good news was that our plan had worked. The frame was now stiff and rode properly. We took it all apart again and glued in some wedges to aesthetically improve the joints then set about cutting back the excess material and shaping the frame. 

Once all the gluing was finished we shaped the frame using an angle grinder with a sanding disc and then followed that with an electric sander. In all it was an afternoon of shaping and sanding. 

I made a mistake...

I will get it off my chest right now.
The Plycycle Mk2 has not been a great success. The Mk1 is great and I still ride it. But the Mk 2 has issues.
The geometry is a mess, the head tube is at a far to steep an angle making the steering super twitchy. and I got greedy thinning down the frame and as a result it is super flexible. So flexible along the top tube that it is not nice to ride. Both of these issues are fixable.

The steering could be fixed with different forks and stem to the handle bars.

The frame can have a section cut away then replaced with a cross grain section of reinforcement.

However i am inclined just to park the project and move on.

I have thoroughly enjoyed the process and I have one great, working wooden framed bike. I am happy to leave it at that..... for the moment any way.

Bolting on more bits pt2.....

More bits went on, handle bars, brakes and gears.... in fact everything except the chain and the new front tyre.

I fitted the new super thing rear tyre and the fit is perfect, less chunky but I think that is OK.

So this is what it looks like so far.

The rear brake line was too short to take he route i had carefully prepared, so it is hanging loose for the moment. I either have to get longer hydraulic hose or reposition the lugs.

There is one big potential problem though. I think ther is too much flex in the frame. I haven't ridden it yet but it just doent feel right. In making it lighter and thinner I may have gone too far.

Bolting bits on.....

It has been a couple of weeks of good progress after a summer of no spare time.

I managed to start bolting on some of the mechanical bits and extra fittings.

But before I fitted the bits i decided to weigh the bare frame as I had neglected to do this with the Mk1. It came in at 3.8 kilos. Now I have no idea if this is good or bad, it is what it is.

Weighing in on the scales, 3.8kg.

So, the bits. Well the head set went in perfectly which allowed the forks to go on. (I had resprayed the forks to match the head tube.) I also fitted the bottom bracket which meant that i could fit the cranks. This was the first real time I could see if the clearance would be good between the crank arm and the rear stays. It was fine, generous in fact.

Vid of the bits fitted so far.

I also drilled and fitted the head tube safety bolts. I used a small drill bit to avoid the exit hole from splitting, but it still did. I expect the bit I used was getting blunt. There is no excuse for that.Still, the split was easy to fix with a spot of wood glue as it was only cosmetic. I then drilled out the holes with the larger bits, and fitted the bolts. I had intended to rig up my small pillar drill but went free hand in the end. I got the holes just right, phew. The bolts look good too.

 

Crank, headset, forks, bottom bracket, crank and seat fitted.

Wheels on test.

The final thing was a wheels on test. I fitted the fresh tyres I had got in for the project, as I was recycling the wheels I thought the least I could do was to fit fresh boots on the bike. Anyway, it wasn't the good news i was hoping for. The back tyre rubbed on the frame. The gap was measured to fit a 1.4 tyre and in my excitement I had got 1.5 tyres. i thought it wouldn't make that much difference, but it does. So to be safe I have ordered a pair of 1.2 tyres. 

PAINT

As I worked hard to get the wooden parts of the frame done, I lost sight of the metal work and in the course of sanding shaping and varnishing I bashed the metal bits and as a result there were a couple of big paint chips. This was a real shame as I had gone to great lengths to paint everything carefully before fitting to avoid painting once fitted. However I did end up having to.

Grinding of the old paint.

As much of the old paint had to come off as possible. If you have ever tried spraying on top of existing paint it never goes well. I tested a bit and sure enough it went like crazy paving. i think it is because the chemicals in the paint below absorb the fresh paint and cause it to shrink. Anyhow, back to bare metal is always best.

Fresh primer, fresh paint, and fresh lacquer.

Plycycle with fresh paint and head tube sticker all lacquered in.

I carefully masked the frame with expensive masking tape around the details and covered the rest in old newspaper. over a couple of warm days I got all the spraying and inter coat sanding done. I was super pleased to get it all on one week.

Rear drop outs all masked and painted.

Bottom bracket masked, and unmasked one painted.

Taking off the masking was nerve racking but fun. It revealed that I had completely missed a few spots, but they will clean up no problem.

Vid of taking the masking off after painting.

i am pleased with the way the painting worked out, it was worth doing.

Varnish issues.

First, it has been a while, more real life has just got in the way....

Back in April I started lacquering the frame. The primer coat went on well as did the first coat. Then the problems started. When cured there were giant runs in the finish. I cut them off (yes they were that bad) and had another go. Again it looked good and smooth as it went on but when I came back the finish was terrible. I ended up pretty much sanding the whole frame back and starting again.

The second time it was July and hot. The varnish went on much more thinly out of the tin and cured faster. It was also well within the recommended temperature all night too. The finish was great, as it was on the Plycycle Mk1, and as I had expected it to be in the first place.

What I learnt was this. Do not rush it. The temp needed to be over 10 deg C. It was when I applied it but in the spring it went down much colder at night. This was not good. If I had actually bothered to think it through properly I would have worked it out and not made a LOT more work for myself.
Applying the lacquer at 22 deg C and an ambient temp of around 15 deg C at night meant that it was all good.

I should point out that my garage where I am doing the work does not have heating and I didn't want to leave an electric heater on over night in there unattended.

The varnish is OK now....

Anyway, the good news is that the frame is now sealed and looks great.

Next job is to fix the dings in the paint work on the metal parts.

Wheels on.

It occurred to me this morning that I had not actually put the wheels on the frame for a very long time. So I did. See the pic below.

I have to be honest and say that I was disappointed, mainly with the forks and the impact they have. The front wheel has a super fat tyre fitted at the moment which it will not in the final assembly so ignore that. The main problem is the rake and size of the forks where it meats the head tube. Being aluminium the crown is very fat and really doesnt sit well by the steel head tube. I had thought that the chunky nature of the aluminium forks world work well, and they do to a certain extent but over all they just look a bit ridged compared to the rest of the frame. Also they are too long as they were intended for a 700c wheel, With the forks being too long it pushes the bike quite high, it was already a short high design, so this just pushes it a bit too far for my liking. There is a simple solution and that is to find a new set of forks. I think I will go for steel this time. I will look for a 26 inch fork that will fit the wheels properly and not push the geometry up. 

ThePlycycle Mk2 with wheels on.

As a result of fitting the back wheel found I had forgotten to carve out the frame where the rear wheel fits behind the bottom bracket. Or rather doesn't fit. I have to deflate the tyre to fit the wheel at the mo. it was on my list of things to do I just forgot. Luckily it is an easy fix, one i will ahve to do before i do the final varnish coats.

There has also been a tiny bit of warping in the frame, and i wonder if it has been because i didnt get it varnished before the winter. it has caused the rear wheel to not align as perfectly as It did when I set the drop outs. It is not a disaster, just disappointing.

On the plus side the first thinned coat of varnish looks good and holds promise for the next full coat.

Varnish-first coat.

It seemed like a long way off for ages and now it is here it is a very exciting time in the project. Like many other stages this is a point of no return.
First coat of varnish. This first coat is thinned down 20% with thinners as a wetting/preparation coat. It may lift the wood grain in places, so it will need a good chack then light sanding before the final four coats go on.
I have chosen the same varnish as last time. It is a yacht deck varnish by Hemple. I chose it for its UV stability combined with strength and flexibility.
Having used it on the Plycycle Mk1 I am very happy with it. I like the high lacquer slightly orange finish it gives. It is not every bodies cup of tea, but I love it.

 

 First varnish coat going on.

You can see from the pictures how much the varnish brings out the shape and contours of the ply. This really changes the way the frame looks, for the better. It clearly looks wooden once the varnish is on.

Varnish first coat.

I just have to be patient now and varnish the frame carefully with out rushing, on days when the weather will be warm enough for it to cure properly.

Last bits done.

The tinkering and noodeling is over. I have finally got the frame to a place where I am happy. Today I spent some time giving the frame a final sand down. The frame has a nice shape to it now and if I carry on sanding any more there wont be any frame left. I have to draw a line under this somewhere and I am happy for it to be now.

I had been round in circles looking for a solution for the seat post fixing. I really didn't want to resort to inserting a metal tube into the frame. Possibly something i will regret if the seat post wears the hole wide with time. But if it does I can always sleeve it at a later date. Anyway, after a lot of hunting I found this seat bracket that has a lamp fitting machined from the same block as the clamp. If the clamp clamps the seat post directly which it does then all that remains is for the rotation of the seat in the hole to eliminated. The clamp will do exactly that once I have screwed it into the frame. Well that's the plan anyway.

 Seat post fixing solution.

 Rear stays.

Its ready for varnish.....

Final sanding video.

Next stop, varnishing.

Refining the frame.

This is a fun bit but also a slow part of the build. Getting the shape to be the final shape. The main aim is to get rid of the excess epoxy, any staining that has occurred and to smooth out the lines and curves. Up until now the shapes have been very crude approximations of the final shape. Now I am loosing all the extra bits, lumps bumps and corners. It takes ages and I have to be patient.

Compare this with last time.....

A closer look with video.

There is still a way to go before it is ready for varnishing, but I am happy with the progress.

I still don't know how I am going to fix the seat post in. Latest thought is to chop off the riser and epoxy it in like last time, but that seems a bit defeatist, so I will try and figure a simple way to make it adjustable.