You don’t need much money to buy speed!

wellsprop wrote:

 

I CAD modelled the initial wheel (a second hand super cheap Mavic Kysrium) before CAD modelling the same rear but with a disc covering the spokes.

I put both the CAD models into ANSYS CFX and ran Computational Fluid Dynamics on each model (I did a mesh study, inflation layer and all that other fun stuff, if anyone wants to challenge the validity of the simulation!). I’ve calculated a drag reduction of around 5 watts at 25mph with 0° yaw angle (I haven’t tested any yaw angles).

In the CFD, the increased vorticity and flow separation are clear for the shallow rim when compared with the disc – hence the drag saving. (The skin friction was much greater for the disc and the boundary layer was able to grow much larger and become turbulent, but even so, the disc was still better overall due to less flow separation).

I used the CAD model to create drawings of the disc wheel and calculate the dimensions and the angle of the cut needed to dish the wheel properly. I purchased some really cheap (cost me about £7) 0.5mm styrene sheet and scored the circle needed to create the wheel, cut the angle for dishing it, bent it together and glued it.

The Mavic stickers came in the box of goodies with my Canyon, seeing as the wheel I used was a Mavic, I thought I’d stick a couple on!

All I did then was put the covers over the wheel (the non-drive side is secured on the inside with tape and the drive side fitted beneath the flange next to the freehub so was held firm) then used electrical tape to secure the outside to the rim. 

It sounds incredible above about 20mph, combined with the trispoke up front it makes the bike sound like a helicopter (somewhere between a Chinook in the distance and a [hovering] V-22) 

Yeah, that’s what I’d have done too, being old skool though I’d probably have done it by hand and also made the last image look like a weird green wheel penis…

asdfqwerty wrote:

I reckon most of the time you saved was from the change in body position because you bought TT bars for the ‘new’ bike. Everything beyond that is marginal. Sure they all add up, but you’re comparing apples to oranges.

I thought that was rather the point – he had an apple and wanted to make a faster orange on the cheap. Seems to have succeeded..

With regards to aerodynamics,
With regards to aerodynamics, many years ago my uncle was building race cars and my cousin was studying similar disciplines. At the time he was racing pedal prix in conjunction with his schooling. Although heavier, the tricycles were clad with an aerodynamic efficient shell and that enabled them to maintain a much faster pace. Understanding that such would be awkward on a road bike to climb into a cockpit, etc, I’m still a little bit surprised that the nerds haven’t developed track bikes and flat land racers that are hiding the pilot between a wall and a wedge. Given that our bodies are much more complicated to manipulate air pressures with than such, yes it would increase weight yet once wound up she should have a lot less drag.
Best of luck.

Fun?
Fun?
Gosh, if the bloke had strapped a rocket to the top tube then PR might have been yanked out of fifth and going double or nothing.
Good man obviously applied knowledge with drag on system to achieve a well earned PR using simple British leverage to his advantage.
Still recon Italian StallIon wouldn’t want to move a bafang fixie into system recognition such that the pillion drives the crank that drives the pillion that drives the golly wog gone way faster, Jack hammer avoided having unclipped after take off.

I’m impressed, my motorbike uses wings behind the calipers to streamline the defused air. Stability is a huge pro. Not sure if modern bikes use similar around deraileurs and such. Didn’t even know bikes had more than 8 rear cogs until 2 years ago.

“R&D testing of bicycle

“R&D testing of bicycle wheels as well as developing bicycle component fairings”

sounds interesting, but I don’t suppose you are at liberity to tell us any more?

FUN:

FUN:

From Middle English fonnen (“make a fool of”) or fon, fonne (“foolish, simple, silly”), probably of North Germanic origin, related to Swedish fånig (“foolish”), Swedish fåne (“a fool”). Compare also Norwegian fomme, fume (“a fool”). More at fon, fond.

As a noun, fun is recorded from 1700, with a meaning “a cheat, trick, hoax”, from a verb fun meaning “to cheat, trick” (1680s). The meaning “diversion, amusement” dates to the 1720s. The older meaning is preserved in the phrase “to make fun of” (1737) and in usage of the adjective funny. The use of fun as adjective is newest and is due to reanalysis of the noun; this was incipient in the mid-19th century.

I will say little more. Cugel, you have small acquaintance with the trade, but I take it as a good sign that you have come to me for training, since my methods are not soft. You will learn or you will drown, or suffer a blow of the flukes, or worse, incur my displeasure. But you have started well and I will teach you well. Never think me harsh, or over-bearing; you will be in self-defeating error! I am stern, yes, even severe, but in the end, when I acknowledge you a worminger, you will thank me.

Cugel wrote:

wellsprop wrote:

I was only drawn to TT as I’m not interested in racing but I want something competitive (at least beating my own PR’s)! I plan to give the local TT’s a bash this season, the local club also runs weekly evening TT’s :)

You aren’t beating your own PRs if the increase in speed is due soley to the technology “upgrades”. This is something I never grasp about TT lads – are you “competing against yourself” or actually in a race with others after all (more like an arms race than a fair fight, since it all seems to hinge on the technology)? I know, really – it’s the latter, innit.

In Japan they have keirin racing wherein the bikes are highly limited in any variation, tending to none, as the punters are interested in which bloke, not which bike, is the fastest.  It was once like that in TTing, where everyone road a fixed wheel bog-standard thing. This makes sense to me.

You could ride a 1939 Rudge and improve your times …. by getting fitter. I thought that was the idea … but perhaps I am old and confused about these modern things.  One suspects that TTing has become a buy-stuff fest like everything else these days. 🙂

Still, your buying has at least been relatively light on your wallet.

Cugel.

I think what he’s saying is that he’s going to run the bike ‘as is’ this season and see how he gets on.