Disc wheel - why rear only??

jimstephenson

As it says. Seen lots of disc wheels in TDF time trials, but why is it only the rear wheel??

I understand the inherent problems of disc wheels ie crosswinds etc, but why not have a front disc?

I have done some searching on this with no success; can some-one sort this out for me please.

Thanks.

redddraggon

It's illegal

jimstephenson

I wondered whether it may be a rule thing.

2 minutes to reply - impressive!

dennisn

jimstephenson wrote:

I wondered whether it may be a rule thing.

2 minutes to reply - impressive!

BUT, why is it illegal?

Bronzie

Some of the boys had trouble staying upright / on-course yesterday with just one solid wheel catching the wind - try that with a solid front wheel as well and you'd be in every ditch along the road.

They do use front discs in track pursuit (indoors only though)

dougzz

Reading this post I was reminded of an American Football kicker who once claimed he missed a kick because he was 'kicking into the air conditioning'

schlepcycling

Bronzie wrote:

Some of the boys had trouble staying upright / on-course yesterday with just one solid wheel catching the wind - try that with a solid front wheel as well and you'd be in every ditch along the road.

They do use front discs in track pursuit (indoors only though)

And in the 89 Tour

Pokerface

dennisn wrote:

jimstephenson wrote:

I wondered whether it may be a rule thing.

2 minutes to reply - impressive!

BUT, why is it illegal?

Because the UCI rules say you can't use one!

Pokerface

Basically the handling of the bike becomes very dangerous with a front disc so the rules no longer allow it.

It's not really an issue on the track where there is no wind to deal with and you're only going around in circle. And on the track, you can only use one in events where handling isn't an issue (pursuit events - not sprint events where you need to move around the track a lot).

don key

And in the 89 Tour

[/quote]


And who won that year?

There's your answer.

edhornby

by 8 secs !!!

and in that last TT lemond was using aero bars which may well have shaded it for him...

Bronzie

edhornby wrote:

by 8 secs !!!

and in that last TT lemond was using aero bars which may well have shaded it for him...

Not only that, but Fignon apparently had a monster size saddle sore so he didn't get a course pre-ride or even warmup. Lemond rode some of the corners 3 or 4 times in practice to get his lines right.

AO1504

This was once legal



as was this



but now both are illegal

dennisn

AO1504 wrote:

This was once legal



as was this



but now both are illegal

Could be a stupid question, but here goes. Is that possibly the same frame painted differently? Or the same frame period, just different labeling on opposite sides of the
tube?

Pokerface

dennisn wrote:

AO1504 wrote:

This was once legal



as was this



but now both are illegal

Could be a stupid question, but here goes. Is that possibly the same frame painted differently? Or the same frame period, just different labeling on opposite sides of the
tube?

Well - if you watch the film - then you would be led to believe it is indeed the same frame.

dennisn

Pokerface wrote:

dennisn wrote:

AO1504 wrote:

This was once legal



as was this



but now both are illegal

Could be a stupid question, but here goes. Is that possibly the same frame painted differently? Or the same frame period, just different labeling on opposite sides of the
tube?

Well - if you watch the film - then you would be led to believe it is indeed the same frame.

Another stupid question if you will? What rules did the powers that be come up with to
ban both of these bikes and or positions? i.e. maybe, your hands can't be in front of the
front wheel or something like that?

redvee

edhornby wrote:

by 8 secs !!!

and in that last TT lemond was using aero bars which may well have shaded it for him...

It was the aero advantage of Lemond's Giro helmet over the unfaired ponytail of Fignon that gave Greg the 8 seconds he won with.

don key

AO1504 wrote:

This was once legal



as was this



but now both are illegal

Who's the guy in the Bran Gritania fit out?

I was woorid I'd fax paused by not knowing what wagon wheels Greg rode with, it was a spokey on the fraunt.The rear I couldn't make out as it had an advertising hoarding in the way.

k-dog

They're both Graham o'Bree - just at different times.

It may well be the same frame - although he had a couple of different ones over the years I think. He had to change the position after they banned the first one - and then the second one.

Another stupid question if you will? What rules did the powers that be come up with to
ban both of these bikes and or positions? i.e. maybe, your hands can't be in front of the
front wheel or something like that?

Stuff like that - constraints on bar and saddle position (relative to BB), max extension of bars (relative to front axle), maximum length of bike (to stop anyone abusing the first 2 rules.

You can get a morphological exemption if you're particularly tall or short but there aren't too many guys who fall into that category.

Alex_Simmons/RST

dennisn wrote:

jimstephenson wrote:

I wondered whether it may be a rule thing.

2 minutes to reply - impressive!

BUT, why is it illegal?

It's not illegal to use a front disk in time trial events run under UCI regs.

It is illegal to use a disk in mass start road events though.

The simple fact is that the steering of a bike with a front disk is very difficult with even light winds and the thought of attempting to ride in a TTT formation with one would be lunacy. Generally you will only see them used on an indoor track, sometimes outdoor ones if it is very still.

disquieting_museeuws

I remember being in a windy time trial once where competitors were walking part of the course because they simply couldn't keep their rear-disced / deep section-rimmed bikes on the road.

andrewgturnbull

k-dog wrote:

They're both Graham o'Bree - just at different times.

It may well be the same frame - although he had a couple of different ones over the years I think. He had to change the position after they banned the first one - and then the second one.

Another stupid question if you will? What rules did the powers that be come up with to
ban both of these bikes and or positions? i.e. maybe, your hands can't be in front of the
front wheel or something like that?

Stuff like that - constraints on bar and saddle position (relative to BB), max extension of bars (relative to front axle), maximum length of bike (to stop anyone abusing the first 2 rules.

You can get a morphological exemption if you're particularly tall or short but there aren't too many guys who fall into that category.

Hi there.

Same frame - "old faithful".

There was a second frame made up by his bike sponsor (specialized) for Graeme's first hour attempt in Norway. This was a copy made to the Graeme's original design. He was persuaded to use it, against his initial wishes and did indeed ride the copy in the first, failed record attempt. When Obree returned to the track the next morning and broke the record it was back on old faithful.

Or something like that.

Cheers, Andy

andrewgturnbull

ps There was an 'almost disc' front wheel that made a brief appearance in the Vuelta TT 3 or 4 years ago. This was a Zipp (or Hed?) disc with 3 small cut outs near the hub to stop it being completely solid and thus circumnavigate the rules.

It was also intended to be used at the Hawaii Ironman tri world champs the following month, where disc wheels are banned on the back as well due to the high winds over there.

However it was quickly banned by both the UCI for bike racing and the WTC who own Ironman. I've tried googling, but I can't remember the name or find any pictures of this wheel. From memory the name might have something to do with Hawaii.

Time trialling under CTT rules in England stipulate that 50% of the area of the front wheel must be open. Wheels like the Planet x 101 are designed right up to this limit.

Cheers, Andy

Jez mon

Would be interesting to see the "almost" disc wheel you are talking about, only similar thing I know of is the "Campagnolo Scirocco"

emadden

incredibly rare to see double discs these days... although I did see this one at the prologue of last year's tour de romandie.... The course was only 1.5km long though... a sprint out and back



What surprises me is that the teams still carry them around in the team truck even though nobody uses them!