Disc front wheel *Outside* TT if windless

ajmitchell

OK this is a slightly crazy question but can you ride a full disc front wheel (or an aerojacket front) outside if its almost totally without wind in a timetrial. Has anyone tried it. First thoughts are no, but in a short event with predictable weather why not? Obviously I am not asking about UCI sanctioned event.

sungod

it's been done, but probably out of hope rather than science, for instance...



vs. a modern aero wheel is a disc any better at the yaw angles you'll encounter with low/no wind? i doubt it, and aside from the wind, there's also the impact of passing vehicles on open road

cougie

Fignon rode full discs in the TdF tt that he lost to lemond. He didn't use tribars though.

Pretty sure they're banned in racing though. A tri spoke would be better. Almost as aero and a lot easier to handle.

What would you be racing with them? Any slight side wind could push you either off the road or into the path of a lorry.

napoleond

It's against CTT rules, minimum open 45% area, even Zipp 1080s, Hed H3 deep and the new Planet X 5 spoke all fall foul of the regulation.
Don't know about Tri though.

Grill

The front wheel on my track bike is faster than a front disc... Also an old 404 with the right tub is typically faster at zero yaw than an 808 FC. No reason to ride a front disc on the road.

DeVlaeminck

Is it now also against uci rules?

Alex_Simmons/RST

DeVlaeminck wrote:

Is it now also against uci rules?

There is nothing in the regulations that specifically prohibits it for road TT.

cougie

Where's the OP gone? What did he want front discs for Anyway?

ajmitchell

hi thanks for the replies. My interest was purely to see if it could be done either alone (getting a PB on 5 or 10 mile circuit) or in a TT. There is almost an obsession with rear wheel discs but little about front. I havent actually got a disc front wheel, but I have got spare aerojacket and a trispoke and also a 80mm planet x deep front. I tested the difference between the planet x spoked and the full carbon trispoke and the difference was 3 watts to attain the same speed with the slower planet x. It would be very interesting to see what speed (and implied power) gains are possible when wind is virtually nil with a fully covered front. However I am nervous to try it in case and gusts caught me out. I'll probably give it is a go on my own on a quiet route and compared with trispoke and report back (time difference / speed difference).

Grill

What was your test protocol? Sounds more like a rudimentary watts to spin estimation than anything.

You won't PB with a disc if you have to spend time and energy keeping it stable.

ajmitchell

Grill wrote:

What was your test protocol? Sounds more like a rudimentary watts to spin estimation than anything

It was a comparison of test rides in real world where everything (all factors) was the same for two rides except the front wheel was switched and the test repeated (at identical ave speed) to see if the effort would be less with the trispoke.

Video of the test protocol here https://www.youtube.com/watch?v=P63k0_A2ABk

Obviously repeating it a few times would have been ideal but laborious.

fenix

Can ANYONE recall a day that was 'Windless' ?

This renders the whoooole discussion pointless.

As soon as i go near the bike it starts blowing a hoolie.

Grill

ajmitchell wrote:

Grill wrote:

What was your test protocol? Sounds more like a rudimentary watts to spin estimation than anything

It was a comparison of test rides in real world where everything (all factors) was the same for two rides except the front wheel was switched and the test repeated (at identical ave speed) to see if the effort would be less with the trispoke.

Video of the test protocol here https://www.youtube.com/watch?v=P63k0_A2ABk

Obviously repeating it a few times would have been ideal but laborious.

Few things...

First is that Chinese trispokes is laughably bad (yes it's been properly tested). Second is there is no mention of the tubs used as this has a huge impact. Third is that is just awful protocol with massive margin of error. Also Strava has really strange algorithms when it comes to power. At the very least he should have used proper Chung methodology and used GC's Aerolab.

Alex_Simmons/RST

ajmitchell wrote:

Video of the test protocol here https://www.youtube.com/watch?v=P63k0_A2ABk

Ugh