Fort 1.25DB Track and the rollers it lives on

You've probably seen my old Fort steel frame before, it's been around for a decade now.

As we speak, it looks like this (ish - different bars), but it's about to have some new wheels.

Current spec:
52cm Fort 1.25DB track frame & fork, powder coated by Armourtex
Rigida Zac19 on generic (Planet-X) front hub with 36 pg spokes
Rigida Sputnik on KHE Lolita BMX rear hub (modified to fit track ends), 36pg spokes
Conti UltraSport Home Trainer tyres
Deda Crono Nero bars, Deda Zero-01 60mm stem, Profile T2 tribars with Ritchey S-Bends and two sets of Genetic Vein grips
Ritchey Comp Stream saddle on Titec X-Wing post
Shimano FC-2200 cranks, Stronglight 56t ring, Token 103mm JIS BB, Wippermann 1Z1 chain
Look Keo Classics

Tacx T1200 Rollertrack rollers even older than the bike.

So far, so what? Well, I have plans, so I thought I'd get the thread started so it's ready and waiting for future developments, most of which will happen below the tyres.

What size is the rear sprocket? Looks tiny and I guess that's why there's a BMX hub on there?

9 tooth driver on the rear hub, giving approx. 165" gear

Same as my hill rep bike then.

I said 165, not 16.5

I meant gear metres, not inches.

56/9 is about 13m, for our forrin readers

hippy's hill climb machine is 165 gear metres. each climb requires merely 1 full rotation. Which he does at 120 RPM.

It pains me to see such a fine training bike when I have to make do with Lady Liz's pixie-sized road bike on the turbo.
Would love to try and push that gi and watch my body crumble under the pressure.

Cheap Voxom BMX hubs laced into Rigida Sputnik rims with DT Champion spokes and ProLock nips, 48h 2X all round

14mm BMX axles cut down to fit a track frame

A load of balls

And we're ready to roll again

why all the spokes?

This maybe a silly question, but could you have used bladed spokes and then built them at an angle to increase the drag?

But that would work...

... altho it might get a bit messy if you went fast enough.

why all the spokes?

for lots of drag.

Asked and answered, all without disturbing my Sunday dinner.

If I've done my maths right, turning the new wheels with 56/12 at 90rpm should be the same power as the old wheels at 80rpm on 56/9, which gets my 4 minute cadence up to the high end of my racing cadence rather than the low end. If I've miscalculated badly, I'm going to need a bigger chainring.

This maybe a silly question, but could you have used bladed spokes and then built them at an angle to increase the drag?

Yes, it's a silly question. 72 bladed spokes for the old wheels would have cost more than the entire new wheels, and the best that you can do is let them wind up by 90° while building, which makes for an unstable wheel. I'm not even sure that CX-Rays (anything wider would need expensive hub spoke hole slotting) at an average of 45° angle of attack would actually produce more drag than 2mm round spokes.

I've not really been following this. Using your maths, how would adding 12 spokes to each wheel compare to letting 10 or 20psi out of your tubes? At your bodyweight / assuming no change in tyres, blah blah.

That's more difficult to calculate, and in general I disapprove of running artificially low tyre pressure on the rollers - running the casings hot and adding extra cyclic flexion seems like a recipe for short tyre life. Also, using rolling resistance as the main load means P=kv² rather than the P=kv³ you get from adding aerodynamic drag, so any error in calculation of power results in a larger error in estimation of speed.

My eventual aims are

1: lower rolling resistance by using larger rollers
2: add aerodynamic drag using a fluid dynamic brake
3: add inertia by a combination of the above

all of this being directed towards an eventual aim of matching the speed/power and Δspeed/power curves on the rollers more closely to real cycling.

I'll let you know what happens with my old Pro 2 Races that are on my 'roller wheels'. I'll be doing some stuff @ 100psi & 90psi (compared to the 110psi I'd been using up until now), and would consider 70psi as the lowest functional pressure, after experimentation, at my weight (~64kg).

So far, the tyres have developed approximately fuck all wear and tear since being retired from the road, but I'll keep an eye on them at these new pressures.

I use michelin pro race on my rollerturbo, they seem to be the only standard tyre that doesn't degrade on rollers....this prpoerty is quite possibly why they slipp off woooden tracks.

Very low rolling resistance - if I end up wanting any more resistance, I might bung on an old pair of 28mm Conti Top Touring :D

First ride, managed 95rpm for the first rep then died on my arse for the next 3, so it looks like I have a bit of head room for now. Which is handy, as a roller upgrade has receded further into the future due to losing ⅓ of my job today.

Bad luck with the job.

I completed my 2x20 @ ≥96rpm. Felt about right.