Why do time trial bikes have gears?

lotus49

Why do time trial bikes for flat time trial courses have gears?

As far as I see it, the only real purpose for gears is climbing or on a course where there is a lot of slowing down and speeding up, which seems to be unusual to say the least. I cannot see the advantage of having gears on a course that is basically flat. Can someone enlighten me?

u05harrisb

Riders may want to change their cadence during the session so gear changes are necessary. However some people do do time trials on single speeds though, hope that helps.
Ben

xscreamsuk

wind can be a 2 gear difference for me either side of the one I want to be in.

lotus49

u05harrisb wrote:

Riders may want to change their cadence during the session so gear changes are necessary. However some people do do time trials on single speeds though, hope that helps.
Ben

As you can probably tell, I'm no expert in time trialling but I would have thought that the increased drivetrain efficiency would be quite a big advantage. Is it common to change cadence a lot? Is it a factor of tiredness towards the end of the time trial or is there another reason?

xscreamsuk wrote:

wind can be a 2 gear difference for me either side of the one I want to be in.

That is a good point that I hadn't considered. On a still day would you still want to use gears?

napoleond

If you have a TT bike with no gears then its use is rather limited to flat one way courses. I've not yet done a TT where I haven't had to change gear by at least two sprockets either way. A few I could have got away with one gear but would not have been as quick.

Ber Nard

lotus49 wrote:

As you can probably tell, I'm no expert in time trialling but I would have thought that the increased drivetrain efficiency would be quite a big advantage.

Pretty sure I read somewhere that Tony Martin runs a massive front chainring not because he needs a huge gear, but because it allows him to stay a couple of sprockets higher up the cassette resulting in a better chain line.

I also seem to recall a prologue time trial that was essentially a dead straight, flat course (the Giro?) where the winner rode an adapted track bike. As I remember, the UCI promptly banned the use of fixed/single speed bikes.

Rob

lotus49

Ber Nard wrote:

As I remember, the UCI promptly banned the use of fixed/single speed bikes.

Rob

That would rather explain it.

Thanks for the answers.

danowat

Even the flattest TT courses have inclines on them, plus, wind is also a factor

Pross

Most people also need to use a reasonably small gear to start off. Even the big, powerful kilo riders struggle to get the pedals moving out of the blocks and I suspect most serious testers are running bigger gears once rolling than those track guys are. It would also be hard to accelerate out of roundabouts etc. if you were on a 53 x 12 fixed gear and many club time triallists wouldn't fancy riding a smaller fixed gear.

edhornby

Ber Nard wrote:

I also seem to recall a prologue time trial that was essentially a dead straight, flat course (the Giro?) where the winner rode an adapted track bike. As I remember, the UCI promptly banned the use of fixed/single speed bikes.
Rob

it was O'Grady

http://autobus.cyclingnews.com/road/200 ... ?id=wilier

ju5t1n

I understand why having a few gears is useful but I’ve never understood why TT bikes have double chainsets. I was looking at a few on Evans the other day that had compacts on them. Why?

markos1963

Even in Norfolk we have a lot of courses that are hilly or have ramps on and off duel carriageways.

maryka

ju5t1n wrote:

I understand why having a few gears is useful but I’ve never understood why TT bikes have double chainsets. I was looking at a few on Evans the other day that had compacts on them. Why?

I suspect the triathlon market is a lot bigger than the TTer market for TT bikes. Most triathletes would be advised to use a compact as triathlon courses tend to be more sporting (hilly) than typical dragstrip TT courses, not to mention running fast off the bike means having good legs, not legs thrashed by turning too big a gear for a few hours.

ben16v

ju5t1n wrote:

I understand why having a few gears is useful but I’ve never understood why TT bikes have double chainsets. I was looking at a few on Evans the other day that had compacts on them. Why?

double chainset if its a sporting course and a possiblity to get the chain back on if it drops off the ring
compact for triathletes lol -- I am one but run 54/42 - 11/23 on my TT

danowat

I've yet to ride a TT course that has caused me to change from a 53T chainring.....

Ber Nard

edhornby wrote:

Ber Nard wrote:

I also seem to recall a prologue time trial that was essentially a dead straight, flat course (the Giro?) where the winner rode an adapted track bike. As I remember, the UCI promptly banned the use of fixed/single speed bikes.
Rob

it was O'Grady

http://autobus.cyclingnews.com/road/200 ... ?id=wilier

Cheers for the link! My Google-Fu was failing me and I was beginning to think I'd made it up!

Rob

Setarkos

O'Grady didn't win though. IIRC he placed in the Top10 but Bret Lancaster took the win on a geared TT bike.

maryka

ben16v wrote:

compact for triathletes lol -- I am one but run 54/42 - 11/23 on my TT

I did say "most triathletes". If you come off the bike on a hilly course and can't run faster than 8 min miles for a half-Iron or oly distance, you're probably riding too big a gear and too low a cadence on the hills and would be better served with a compact. But I guess my Ironmans have been done on hilly courses so I'm biased.

sunburntknees

ju5t1n wrote:

I understand why having a few gears is useful but I’ve never understood why TT bikes have double chainsets. I was looking at a few on Evans the other day that had compacts on them. Why?

Because they're entry level bikes aimed at beginner triathletes?

phy2sll2

Riding to or from an event?

BeaconRuth

danowat wrote:

I've yet to ride a TT course that has caused me to change from a 53T chainring.....

You should try riding some REAL time trials then Dan........... such as this one: viewtopic.php?f=40041&t=12842173 I'd like to see you try to ride up Ankerdine in your 53.

Ruth

SBezza

danowat wrote:

I've yet to ride a TT course that has caused me to change from a 53T chainring.....

You haven't lived yet then Danny, you ought to try BeaconRuth's LMTT, you will be changing out of the 53 then without a doubt.

Hardly any TT courses are flat in the UK, even the drag strip courses, I use virtually all my gears on the sprocket during the season. I will use the small ring maybe 1 or 2 events, but I ride hilly TT's as well.

danowat

Nah, I am too fat for hilly TT's, why do you think I TT in the first place!

markos1963

I couldn't get up Ankerdine with a compact! :oops:

peejay78

danowat wrote:

Nah, I am too fat for hilly TT's, why do you think I TT in the first place!

hilly TTs are the best thing about the discipline. way way more interesting and challenging than DCs, with a much better sense of camaraderie amongst the 'sufferers'.

toasted whippet

I have ridden fixed and geared TT's - I find that the fixed is better for going up hills - its the downhills that you need gears for (I can't pedal very fast)

Never used the inside ring on a TT - took it off once, and promptly dropped the chain 3 times in the next TT, so back on it went.

Plus riding out to the start, as someone said already.

andy_wrx

Ask the question on timetriallingforum.co.uk

There are a number of TT'ers there who are diehard on fixed gear (usu BIG fixed gear), reckon it's quicker than a cassette.

Obree was one when TT'ing domestically in the UK : set a record in the Tour of the Trossachs which was considered 'hilly' (for Scotland !)

I guess it will force you to push hard uphill to maintain cadence and hence speed, when having multiple gears could tempt you to drop down a gear or two and hence slow down. This uphill gain will more than make up for the speed you'd lose spinning downhill rather than being able to change up and push a bigger gear coming back the other way.

In hillclimbs, then assuming you have the gear right, the lower weight and no temptation to faff-about changing gears must make it quicker too.

For myself, I'm not a strong enough fixed rider to do it, I feel I need my gears although generally I don't use that many of them even on rolling, not dragstrip DC, courses.
I do run a 12-21 9sp cassette, with 1-tooth gaps apart from 19-21, and 55/42 chainrings : the 42 is there for getting over steeper hills on training rides, where I might struggle on 55-21

Zingzang

Pross wrote:

It would also be hard to accelerate out of roundabouts etc. if you were on a 53 x 12 fixed gear and many club time triallists wouldn't fancy riding a smaller fixed gear.

I've never met any cyclist who would seriously consider riding a fixed 53x12.

Pross

Zingzang wrote:

Pross wrote:

It would also be hard to accelerate out of roundabouts etc. if you were on a 53 x 12 fixed gear and many club time triallists wouldn't fancy riding a smaller fixed gear.

I've never met any cyclist who would seriously consider riding a fixed 53x12.

Exactly and yet most testers will be using a gear of that size when riding a flat course hence the comment. A lot of time triallists would struggle to maintain the cadence required to use a sensible fixed gear ratio as the preference seems to be for mashing big gears.

Trev The Rev

Pross wrote:

Zingzang wrote:

Pross wrote:

It would also be hard to accelerate out of roundabouts etc. if you were on a 53 x 12 fixed gear and many club time triallists wouldn't fancy riding a smaller fixed gear.

I've never met any cyclist who would seriously consider riding a fixed 53x12.

Exactly and yet most testers will be using a gear of that size when riding a flat course hence the comment. A lot of time triallists would struggle to maintain the cadence required to use a sensible fixed gear ratio as the preference seems to be for mashing big gears.

What sort of gear would Obree and Boardman have used when they rode fixed on the road?

greasedscotsman

Trev The Rev wrote:

What sort of gear would Obree and Boardman have used when they rode fixed on the road?

On a wet Saturday evening in 1993, Chris Boardman ( North Wirral Velo-Kodak ) shattered his own 25 mile competition record on 110" fixed. Riding on a revised version of the H25/13 course based on the A34 at Oxford, his plan was simple. Turn the110" gear at 102 rpm and he would do a 47. Chris being on top form during his build up to the hour record attempt looked rock steady and keeping his heart rate at around 180 bpm made the ride look effortless. Choosing a bike with fixed rather than gears resulted in a 30% reduction in weight, Chris was able to stay well on top of the gear and record a 45-57. After the ride Chris said he thought he would be unable to father anymore children after bouncing all over the saddle on the 2 mile downhill start. Personally I would tell Chris to stop moaning and try riding the medium gear.

http://www.fixedwheel.co.uk/fixedwheel%20records.htm