Showing posts from August, 2022

The Steel Arrived But Some Changes Are Necessary

The main frame is cut and ready to be welded, if Melbourne will only give me some decent freakin' weather to get outside with power tools. The crossmember needed a rethink. It's all well and good to make a sensible "engineering" decision (I'm a sound engineer by trade, which isn't a field of actual engineering) and use 35x1.6 SHS for all the main parts, but the decision then leads to using 50x5 SHS for making the lean steering wheel tilt brackets and slightly less than 600g of steel for each. Making the same brackets out of 40x3 reduces the weight to nearer 200g each, but requires the crossmember to be made from 30x1.6, also lighter but for no appreciable loss of strength. For my next trick, I might build a version of it out of 31.8x16x1.6 EHS for AeroAdvantage™. Meanwhile, as an exercise in learning FreeCAD, the design is being refined for a later version. A friend is considering an eTrike as a mobility aid and, if mine works, I'll probably start assem

The Steel Has Arrived

The steel arrived on Thursday, thanks Moorrabbin Steel . I haven't started working on it because I spent 2 and a half days in hospital with a repprise of the ticker problems that got me started on this project. I'm OK, more sleep deprived, than crook, but the angiogram showed nothing, despite feeling like an elephant had sat on my chest on Tuesday afternoon. I have 2.5m of 35x35x1.6 SHS, a half metre piece of 50x50x5 SHS for cutting the tilt brackets from, some 30x30x1.6 SHS for the arm of the pedal bracket (and an old bottom bracket shell from a bike frame), some 38x2 EHS for a head tube and a 190x inch 1/8 steerer from the donor bike that provided the bottom bracket. The rear triangle is also from a donor dual suspension MTB. Triceratops Two.1 will get its own rear tri. Racks will be integrated steel racks, built from 12x1.2 EHS, once I've done a billy cart test. Meanwhile, the disk brake hubs have arrived and fit the wheelchair axle bolts pefectly and run beautifully.

Mullet Hacking 10 Speed, "Thumbie," Friction Shift

I am more than a little over indexed shifting. In the days of 3x7 (ah, the 90s) you could setup chainrings that would give you near 500% gear range, while never having to change more than one step at a time - eg: righthand 1, 2, 3, lefthand 1 to 2, righthand 3, 4, 5, lefthand 2 to 3, righthand 5, 6, 7 and back down. Indexed gearing really helped with this at the end of a really long day. Now we do the same thing over 10 gears on a single chainring and only the righthand shifter for no better ratio, but the indices are finer, trickier to set up, bump your derailleur, and you're tweaking for the rest of the day's ride. Ugh. On the other hand, in the days of friction shift, the setup only needed to be right on the derailleur stops, the shifting was tuned with every gear change, and it wasn't a hard knack to master. My first adult bike was a Roadmaster Grand Tourer 12, 2x6 friction shift on the downtubes, the best bike money could buy for under $200 Aussie in 1982. That bike t

Final Design Commit: Triceratops Two

This is the beast I'll be building as the weather in Melbourne begins to improve with the impending spring, the Triceratops Two. For now, T-One is DOA because I think there will be less tweaking involved to get the tracking aligned on T-Two and the cornering will be as tight as a road bike under Cadel Evans' captaincy. The preliminary OpenSCAD code for the design resides on my GitHub.