quilkin

Yes, it's a 'fixie' (fixed-wheel bike); there's no freewheel so you can back-pedal to stop it. Rear brakes aren't required (or even legally required!) on fixed-wheel bikes. Also a rear brake would need some very long flex cables; I tried joining some together but wasn't happy with the results. A freewheel won't be impossible, maybe that can be a future project, but I think I'll go for 1/2 scale rather than 1/3 scale if I build another.

It's pretty well finished (for now at least) - you can see it here - including working brake, dropout wheels, water bottle, and pump (!). I started with the frame, (I have mostly yellow beams) then found the cheapest 1x2 thin liftarms (for the rims/tyres) on Bricklink were red or gray. Yellow 2x1 liftarms were not ever made! Maybe I'll do a red frame one day to match. About the wheels, is it off-limits to strain Lego parts in this way? Real bike wheels are under a lot of stress, they have to be, so I maybe it's OK. Thanks again for help from contributors.

The part I most often need is simple: a combination of this pin and this axle pin so you can join three liftarms, only one of which has an axle hole.

Thanks again, allanp. Your ideas have put me on the right track; the set of 6 x 4019 gears is too big (and the liftarms make it too wide as well) but the same idea works fine with 8-tooth gears, and I can even fit the spoke retainers underneath! Some nice mathematical patterns emerging here...

Many thanks for all the suggestions! Yes, my forks were too thin, after some experimenting I found that a double liftarm 32271 held together with some 4x2 studded plates makes the perfect slot for an axle. And I didn't realise that the 2695 wheels were free-spinning, that's good. I know about the threaded axle but the little nuts are too fiddly, I think I can use some discs 2958 on normal axles to clamp them in place. So, next stage is to somehow get the rear sprocket driving the 2695 hub without driving the axle. (It's a single-speed 'fixie' by the way, maybe designing a derailliuer and freewheel in Technic is going a bit far for this stage.)

Hi all I've recently come back to Technic after a 20-year gap and am finding all the new studless parts & techniques far more interesting than the studded ones. OK, I'm aware that my opening statement may cause some controversy. Anyway, I've recently got 2 new sets (8292 and 8265) as well as several small Bricklink orders. I'm building a one-third scale model of a racing bike, and am now satisfied with wheels, frame, brake, chainwheel, etc (even a water bottle). But I can't figure out any parts to use for the wheel drop-outs, and also how to make the wheels spin on a fixed axle. The drop-outs ideally needs to be a part with a slot just wide enough for an axle. The current arrangement means that the whole axle needs withdrawing from the frame in order to remove the wheel. (OK I know this bike on't ever get a puncture) I could get the wheel to spin by drilling out the center of the pulleys I have used for the hubs, but modifying Lego parts isn't allowed! Maybe there's the ideal parts hiding somewhere amongst all the Pirates or Bionicles sets that I know nothing about. Any ideas? When the whole bike is ready I'll post details here, if anyone's interested....