Friday, 29 June 2012

A dropout rethink methinks

The dropouts have been preying on my mind while I have been busy sorting out the Gazelle the last week or so. I was never 100% happy with the tensioner adjustment being below the chainstay, I imagined careless parking would probably bend the screw, plus the design did not have the simple elegance that I look for when designing things - and when you get that, you know you probably have it right. A comment from philthy on my last post got me thinking about the durability of the dropout material, and that I should probably have made them from proper CroMo to match the rest of the frame, or at least faced the dropouts with stainless steel. Either way this meant I had probably wasted some time machining up those new ones.

However in my opinion, wasting time getting things wrong is the prime causes' way of preparing you to eventually get it right, so I have decided to have another go...

The initial design with the standard dropouts was going to require some tweaking of the bottom bracket chainstay angles to get the fit right, and once I set the new dropouts up in the jig it was pretty obvious that getting a few degrees off center angle on the chainstays was not going to be a problem.

So last night I sat down for a CAD session at the computer (my wife was gallivanting around the frankly scary pub selection in Addington with her Plunket/coffee/wine/AA group, and I was 'babysitting'), and assisted with my own suitable brain lubrication I smashed this out;

This design has the benefit of the adjustment being inside the frame, plus there are less curves and angles, making it more pleasing to the eye in my opinion. The only real issue is the adjustment screw taking a significant amount of meat away from the connection between the chainstay and the seatstay, but I can always beef this up some more, we will see. I call this design the frogmouth MkII, for obvious reasons.

Now I need to source some 8mm 4130 steel, and get to cutting...

I have been thinking hard about the brakes for this bike, initially I was intending to put standard MTB brakes. this would be ok but maybe not that pretty, I think that these might be a better option;

They are nice, if a little bit hard to get hold of in NZ.

The Gazelle has continued as it started, ie being extremely truculent no matter what I try to achieve with it, however the journey is fast drawing to a close. So close in fact that I foolishly decided to ride it to work yesterday. There were a few teething troubles (I needed to stop at least 4 times to adjust the gears, tweak the guards, clean my undies after trying to stop in traffic). I did however get a scalp on my ride home, but this was simply because I had maxed my FCN, so everything on 2 wheels was fair game.

Still it was fun, and I took a couple of pics to mark the occasion;

Those wheels where very time consuming, I bolloxed it up the first time not realising that the spoke holes were offset, plus I got the lacing wrong, plus the rims turned out to have larger than standard nipple holes, plus the spoke lengths were not quite right, etc etc... Dave very kindly sorted things out for me though, he is a solid chap.

I still need to shorten the brake lever arm at the front to make the brakes actually perform their function, and maybe find a new gear cable. And probably sort out a chain guard. And maybe find a pannier for it. Apart from that I think it is looking pretty swish and rather gentlemanly, don't you think?

Sunday, 17 June 2012

Dropout fun

The great ebb and flow of shedweek has turned in my favour this last couple of weeks, the details of which will remain sketchy for fear of reprisals, but in short it involved my loving wife getting her way regarding the outside tiles currently being replaced by the insurance company, and yours truly paying a not inconsiderable amount of money to achieve tile satisfaction. Money well spent, as the look I get as I slink out the garage is significantly less worrying...

Anyway, this was the state of play a week or so ago, with all of the main tubes mitered in and looking pretty shmick I must say;

Now a while ago I mentioned some custom dropouts getting laser profiled, and these have mostly been the focus of attention this week - apart from a short evening mitering the chainstays into the bottom bracket.

This is what they looked like when I picked them up;

Now at this point I had the brilliant idea of using my lathe as a milling machine to cut away the excess steel on the faces, and that surely some form of compound slide attached to a vise, and then attached to the slide of the lathe would be functional, if a little awkward. The only immediately available thing (ie accessible from the comfort of my computer at 9.23pm on a Sunday night) was this thing on TM with a online price tag of $60. 'Gosh that is cheap' I thought to myself, 'how bad could it really be?' As it turns out the answer to that question is; 'Really, really bad'. So bad in fact, that it turned out to be not only laughably poorly made, but actually impossible to use...

Now using my crude illustration above as a visual stimulus, imagine the top slide being wound backwards and forwards (and feeling disturbingly crunchy while this is happening). Then imagine if you will this backwards and forwards movement causing, by way of a pretty significant interference, the two highlighted nuts to rotate. The more astute amongst you will realise that those two nuts are the locknuts for the slide adjustment, and that for these to rotate by way of moving the cross slide is in fact a wrongness that is so fundamentally wrong it is difficult to find expression for it.

I should have known really, I took the punt on a hydraulically adjustable work bench from the same company once for an assembly jig I was making, imagine our surprise when it turned up and the working surface had a built in drainage drop of 50mm across 600mm of table, but only in one corner....obviously the lesson learnt had dulled over the years and the prime cause had decided to refresh things for me.

So anyway, I then went to a real engineering supplier to try and find something better. After describing my experiences and what I wanted to achieve to the very helpful man, he stifled his mirth and said I should really talk to Sam. Sam was a small man with a rather impressive grey beard who had just arrived in the shop and was waiting patiently to give me his personal opinion of Topmaq, which was not very complimentary much to my surprise.

It turns out that Sam has a superbly equipped home workshop plus many interesting things to look at, including sweet vintage AJS and Matchless motorbikes. So for a couple of boxes of bourbon and coke Sam gave me free reign of his machinery, and the milling machine in particular got a fair bit of use, so I ended up with this;

I then spent this afternoon with files and a dremel to get to this state of affairs;

Clearly there is a bit more to do there, but you get the idea...

In other news, I have purchased two new 28" rims from Dave, and have got the Gazelle hubs nickel plated. I (or Dave) just need to figure the correct spoke lengths and I will build those boys up pronto.

The Gazelle better be bloody grateful is all I can say.

Thursday, 7 June 2012

Mostly the gunblued bike...

Things continue apace at Pogwards Large Emporium of Bicycles, the frame jig is finished enough to hold the main bit of the frame in place, and as such I have mitered the top tube and intend to start the downtube as soon as my shedweek is allowed to begin. This has been hampered by my eldest child's birthday party and the accompanying doting grandparents coming to visit. Even now I shudder at the thought of ever again having to endure in the same room a dozen 9 year old girls screaming the words to some dreadful One Direction song at the top of their lungs. Or for that matter having to constantly explain the workings of my Fathers Samsung Galaxy SII to him, ie the difference between an operating system and an app....He is the only person I know who still remembers all the phone numbers he needs, and this is simply because he cannot learn how to make a speed dial shortcut or use the search function. I am not sure how things have come to this sort of pass but apparently spending several hours machining brass in the garage rather than trying to cope with all this is frowned upon in modern society...

Framebuilding progress has been hampered by many other bicycle related nonsenses, ie getting the devastatingly handsome Bob to face the bottom bracket shell of the Gazelle for me (the shell being 70mm wide I had faced it back to 68mm with all the precision that can be had from an angle grinder - ie, not much precision). During the visit Bob also started handing out old 28" guards with a feverishness that can only come from the sure knowledge that doing this sort of thing can be bartered for extended shedweek. All this meant that the Gazelle now looks like this;

I am now working on getting the drum braked hubs up and running. Last week I stupidly totted up the probably cost of doing this (spokes, rims, tyres, replating the hubs etc), and I found myself breaking out in a cold sweat and talking in a squeaky voice for a while. After my testes had descended again I reasoned that I could simply sell every other wheelset I had, and when I needed to use a particular bike I could swap the wheels into that. Problem solved.

In other exciting news, a present arrived in the post for Gunmetal Bike - a NOS Campagnolo crankset in a very desirable (to me) 175mm crank length;

Gunmetal bike started as a pretty rough Tarini Tange 2 frame that I got for $20 off TradeMe, which I decided had to be gunblued. Due to the fact that I was excited by my success in so easily sourcing a pot of bluing compound, I slapped the stuff on without really reading the instructions..... this *kind of* went badly as a result, so I ended up doing it all over again. This means the colour is more chocolaty brown than blue, but I like it a lot.....

I really like how you can see the brazing beneath the finish, and the sweet Porteur bars, and the saddle, and pretty much everything... It is also ridiculously light, so the big gearing doesn't hurt my knees so much.

This bike is still a bit of a work in progress, as you can see there are a couple of areas that could do with improvement, and I might even build a new set of forks for it sooner or later.....