Red Bikes: Dolan Disc³

Slightly unrelated, but any recommendations for cheap frame builders?

Dolan pre cursa is somewhere between 74-75 headtube. The geo chart is not correct. The seattube and headtube are basically parallel, so something is wrong (actually... right) there.

My best guess is this for size 56 with the alpina fork:

Headtube angle 74.7 / Seattube angle ~74.7 / Stack 553mm / Reach 414mm /Front-center 584mm

The geo chart is not correct.

Why am I not surprised by that? Dolan doesn't even know their own frame sizes.

Fair point, @Hulsroy build his own frame with a steep headtube similar to your to gain the low trail handling you also enjoyed.

I was thinking of mielec, there is a lot about them here -> https://www.lfgss.com/conversations/217358/
-> http://www.bikemielec.com/en/

Svend, you seem to have a lot of patience and engineering skills.
May I suggest you get a steel frame of proper quality tube. Maybe a track frame with a cracked headtube or and older touring bike with horisontal dropouts.
Then you replace the headtube (with a cheap Ceeway Cromoly one) using the string method (Patent Pending).
You can buy a disc tab for 10gbp on ebay and build a cheap fixture yourself.
Then all you need is to find a person with tig welding skills and half an hour to put it together..

This may be a dim question, so I apologise. Is the "string method" simply holding the tube to be welded in place instead of using a jig? If so neat idea, although its still a bit of a job to remove the head tube and mitre (if that is the correct word) the cut joints to fit the new tube.

Yes. It was an easy way to hold the head tube in place while tagging it. I am only suggesting this to Sven though, as he seems capable.
There is of course some filing required. But you get mitres from an online generator based on tube sizes and angle. Then you cut and file until headtube is straight and in the preferred angle. That is where patience comes in

Ha! Thanks for the compliment, but i guess such traits also come with stubbornness. I think i'll see where this goes first.

Welding would be great to learn... later...

I really liked all of your headtube conversions, if I ever run in a crushed headtube 90ties steel for cheap, I will be asking for a lot more info. I can get stuff brazed for cheap back at home in Croatia, so a donor frame would kick this off. What´s the best way to approach the brazing of a disk tab at a fairly standard rear triangle (i.e. position, reinforcement, homemade jig..)?

For ISO it is basicly a piece of flat 5mm sheet of steel (or whatever you choose) with two holes placed in the right distance from hub axle.
Peter Verdones wiki has all the shimano measurements for this.
Re jig you just make your own, I have shared photos of mine before and I will not clutter this thread with anymore diy spam.
I can share some photos of my latest mod in the CP thread later.

Haha it works:

This is version B in aluminium as 3mm steel was too bendy. Further refinement is to make it possible to easily remove the wheel. Currently it is locked in place like an internal gear hub. Still a prototype.

revised sketch:

Crazy nice. What prevents it from rotating and rubbing against the rotor?

Thanks. The black clamp + small metal wedge (left green part on drawing) seems very secure/non-sideslipping now but yes that could be a part that could degenerate with use.

I have tried to make the blue part press straight down over the "exact" middle of the chainstay tube hence the slight offset of the slot at the left side. Seems to work (now).

edit: blue part is also pretty un-twisty and solid

Nice. At least you cannot die from back wheel failure

This thread is ace. Truly the essence of lfgss

Thanks!

sorted out routing the front brake hose through the fork steerer. Now with a connection point.

It is a piece of handlebar with m20 thread cut on the inside that is epoxy glued into the steerer tube.

and then a m20 crank arm bolt is used as a top cap. The hole in the middle is a perfect fit for a brake hose fitting.

It would be a really neat solution if the crank arm bolt was slightly larger as now it needs another topcap with a big hole cut in it underneath to work (the greenish bit in the first photo)

Absolutely legendary solution. This whole thread is just so good! I love your approach to making something do what you want it to.

Did you have to do anything to combine the hylex lever with a shimano caliper?

No.
They both use mineral oil and the same type of standard fittings. The pistons are not the exactly same size (something like 21mm vs 22mm) but I have not noticed that (like using slightly different cable pull on mechanical brakes).

edit: Ok the above is not wrong but a bit imprecise: Shimano and hylex use the same m8x0.75 compression nut, but the olive+barbs are different. Its easy to use the correct kind.

Thanks. Its fun to make stuff (and also a sort of procrastination...)

Excellent work and a rather neat solution. I may be paranoid but I'd stress slightly about the epoxy giving way during extreme braking. I was thinking about this and one way to negate the need for epoxy would be to tap the fork and insert a thread "seat" onto which you locate your handlebar piece followed by a thin threaded lockring, thus mechanically fixing the the handlebar piece. Then locating the crank arm bolt top cap. I'm note sure what your fork is made of though and if it would be wise to tap the bore of even a steal steering column.

Fork has a carbon steerer, but...

On a fork the top cap is only for preloading the headset (and later act as a raincover...) and after you tighten the stem it is only the stem that holds the fork on.

Sorry I appreciate the purpose of a normal top cap. However yours is serving two purposes..... and I have just realised that a hydraulic brake system doesn't experience the same forces in the line as a cable system. Sorry I was being thick and have never used hydraulics.

ahh ok