time trials and "solid wheels"

[Jake]

QUESTION!

why use, what i have just called, solid wheels. Usualy the back wheel has no spokes, or a solid style cover, if you know what i mean. Surely they are heavier? and if its windy then your going to get blown all over the place and loose stability. Or if they were so good, why arnt they always used? Also the time trial bikes are so different then the road bikes in design, agian looking much chunkier and heavier.

Also notice on this years TdFrance, and in the bike shops, that the innter part of the wheel is bigger, maybe 3-4 inches, where as monie is just the breake area and a bit more for the spokes.

 

[wafflycat]

Disk wheels are more aerodynamic at speed than a spoked wheel, hence their use in TTs. Some are very light (son has Zipp rear disk and it is feather-light) and some aren't (Son used to have a Renn and it was very heavy by comparison, and a HED, which was just heavy by comparison). They aren't always used due to the effect of a crosswind - which is also the reason why, on a TT bike they are only allowed on the rear wheel. On an indoor track, disk wheels can be used front & back. The increasing rin size for front wheels is an attempt to gain some of the aerodynamic advantages of a solid disk wheel whilst lowering the disadvantages of instability in a crosswind.

"where as monie is just the breake area" In English please - does not compute!

PS The Zipp wheels are a beautiful bit of engineering. Even I, as a non-competitve cyclist can appeciate how lovely they are. Light as a feather, beautifully balanced..

Edit: They are not used in road races because, apart from the above, the cyclist has to ride solo ina TT - no bunches, so if the cyclist has a wobble issue, he/she isn't going to bring down the peloton.

 

[Theseus]

"where as monie is just the breake area" In English please - does not compute!

I read that as "where mine just has the brake surface"

 

[Jake]

i think i meant was , the wheel rim was only by the breaking area and a little bit up by the spokes, where as these new wheels are a couple of inches deeper.

Intereresting about the disks, thanks. can feel my front wheel being hit by the wind sometimes.

there were some jokers using them in the triathlon though where by what you say, they should not have been as it was a race.

thanks

 

[Banjo]

Some guys riding solid disc rear wheel bikes passed me a few sundays back .I was amazed at the clattering noise from them ,any idea what thats all about?

 

[Jake]

yes they do rattle and bang, sounds like riding a piece of hmmmm, well, perspex or something. very odd.

 

[wafflycat]

The sound of a lovely Zipp disk at being cycled at 30mph on tarmac is a quite lovely swooshing sound

 

[Jake]

round Blenhiem it didnt sound too good in the rain and wind, and i certinaly doubt it sounds nice on the roads of london which now resemble the Somme.

 

[ttcycle]

Technically some triathlons (the london one next weekend anyway) are TT's as no race tactics such as drafting are allowed so suppose that's why people are using the disks.

BTW OT but is anyone London based that may be able to cover my cycle olympic distance (25miles) leg of next saturday's triathlon -been training hard for the team relay which is now all gone to pot as I've got confirmed swine flu but thought I'd put feelers out incase I'm not well for then so my team mates can still race.
PM me if you can do it and will get back to you if I'mstill unwell and definetly can't race myself

 

[Jake]

away otherwise would have been doing it myself

 

[Ben M]

It's more aerodynamic than a normal wheel.

If you look at the frames of TT bikes the tubes are also shaped more aerodynamically, often making them heavier than less aerodynamic frames.

Why did you post this thread in commuting?

 

[simon_brooke]

Some guys riding solid disc rear wheel bikes passed me a few sundays back .I was amazed at the clattering noise from them ,any idea what thats all about?

The whole surface of the disk acts like a drum-skin or sounding board, and yes, they can be very noisy!

i think i meant was , the wheel rim was only by the breaking area and a little bit up by the spokes, where as these new wheels are a couple of inches deeper.

It's all about aerodynamics. Wheels make up a surprisingly large proportion of a bike's total aerodynamic drag, so any way you can improve them is good. The effect of the front wheel is considerably more than the back, because the front wheel runs in relatively clean air. Unfortunately front wheels which are very aerodynamic also tend to have steering issues in cross winds, which is why disks are very rarely used on the front.

 

[Jake]

ahh ok. i see. interesting stuff. cheers