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Old 29th June 2012   #51
mdcc_testerdonor
 
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Originally Posted by djm778 View Post
I'm also thinking of putting together a fixed TT bike (also be my first TT bike). I'm going to be doing it on a shoestring, and have been looking at some frames or framesets like the dolan precursa or tifosi pista, would this be a good basis for a fixed TT....any thoughts?
Most people use a small track frame for fixed TT use. As an example, I used a 53cm Koga FPT, while I'd have bought the 56cm for sprinting. I've now switched to a 51cm Cervelo T3 with 60mm of spacers under the tribars to get the base bar lower and create a space between the wing and the elbow cups

For a budget build, I'd keep an eye on classifieds (not just here) for an older steel (531 ideally) track bike or frame. The thin tubes are stiff enough for TT use (really, they were stiff enough for Olympic track sprinters back in the day) and since nothing under 2k has been designed to be actually aero rather than cosmetically aero, you might as well stick to keeping the A part of Cd.A down. PNut uses an old steel frame and he has gone <20:00 for 10 miles.

Since you don't yet know what position you're going to adopt, and it will change with practice and development anyway, you're going to have to take a bit of a punt on the sizing. "Stack & Reach" is the sizing model you need to think about, and of those you need to concentrate on reach, since this will affect the handling. Stack can be fixed with stem angle and risers under your tribars, but fixing reach with extreme stem lengths messes up weight distribution and tiller geometry.
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Old 29th June 2012   #52
chillipepper
my regular gear here in cornwall was 99", there is a course on the Lizard that has some very steep bits so dropped to 93, 94" or something, i chose a gear based on the time I wanted to do on a course.. so say I wanted to do a 21 or 22min '10' I'd need to average 27mph say, so I looked at a cadence of around 115 for that meaning I could go faster, up to say 140rpm on the bits that went down, and slower, say 85rpm on the up bits.. or slower out the saddle if it was steep.. which is how I settled on 99".. It did mean beasting it a bit but it seemed to work pretty well as a rule most of the time.
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Old 29th June 2012   #53
Dammitdonor
 
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I'm going to pop out and try the course with 52X14, if I can push it up the hill then it would be 140 rpm for 41mph down to the finish, which I reckon should be ok.

Size- I've got a position which seems to work on the 58cm Langster- but with a 60mm stem.

I think a 54cm might be the one to use, although I'd certainly have a seatpost like a broom stick at that point.
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Old 29th June 2012   #54
markairsy1donor
 
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Originally Posted by whittle View Post
heres mine (although i just sold the frame)
did you not just buy that frame? or was it an old thread revisited recently?
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Old 30th June 2012   #55
djm778
 
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thanks for that mdcc, that gives me something to think about and work on.
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Old 30th June 2012   #56
mechanical_vandal
 
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Originally Posted by Dammit View Post
I'm doing the same thing, currently pondering gearing for my (far, far too large) Langster framed TT bike.

The TT that I am going to do is the Bexley 10, which goes uphill for 4 miles and then downhill for 6, so you need a gear that you can push up the hill that you then don't spin out coming down.

This is something of a challenge- FixedWheelNut was running 97 gear inches, which he pushed up a hill that had me shift to the inner ring.
Inner rings, where fitted, should be kept sparkling clean and unused in order to show how well used the big ring is.
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Old 1st July 2012   #57
Dammitdonor
 
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I am aware of this
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Old 3rd June 2013   #58
Eingangdonor
 
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i never tried time trialing, but as my dolan seta is not really in use i'm thinking of rebuilding it for a first fixed time trial test.

i have a 14t in the box so gear ratio would be 48/14.
syntace stratos 200 is already mounted, so i only need the aero bar.
i'm not sure if i should change the seatpost or the stem, will see how i sit on the bike with the aero bar.

any further advice or typical first mistakes???
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Old 3rd June 2013   #59
_dan_donor
 
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don't lean
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Old 3rd June 2013   #60
hippy
 
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Don't stop pedalling.
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Old 3rd June 2013   #61
mdcc_testerdonor
 
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Don't sleeveless
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Old 21st June 2013   #62
Gaston Fr
 
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Old 21st June 2013   #63
Gaston Fr
 
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Old 21st June 2013   #64
Gaston Fr
 
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Quote:
Originally Posted by whittle View Post
heres mine (although i just sold the frame)

http://img831.imageshack.us/img831/1426/img7510j.jpg
inverted photo with inverted tipo ?
WDF ?
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Old 21st June 2013   #65
mdcc_testerdonor
 
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Quote:
Originally Posted by Gaston Fr View Post
WDF ?
Shouldn't that be W le F?
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Old 21st June 2013   #66
mdcc_testerdonor
 
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By the way, it's left hand drive; aren't all Continental bikes like that :-)
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Old 21st June 2013   #67
mdcc_testerdonor
 
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Quote:
Originally Posted by mdcc_tester View Post
PNut uses an old steel frame and he has gone <20:00 for 10 miles.
Et voila:
Quote:
Originally Posted by Gaston Fr View Post
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Old 21st June 2013   #68
PiemelPiemel
 
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That guy should get an aero helmet and shoe covers before even thinking about an aero frame.
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Old 21st June 2013   #69
Colin the Bald
 
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^My mate Pete uses neither and just got 8th in the National 10, oh, and he's a vet.... Heart and lungs beat marginal gains most of the time.
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Old 21st June 2013   #70
ncjlee
 
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Does he have those aero ear piercings though?
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Old 21st June 2013   #71
Colin the Bald
 
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Nah, his 'him' is aero, the little sod is so skinny there's nothing to hide behind when he's on the front in training.....
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Old 22nd June 2013   #72
PiemelPiemel
 
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^^^ Your mate Pete should also have an aero helmet and shoe covers before getting an aero frame. Marginal gains beat smaller marginal gains. Heart and lungs are irrelevant to this statement.
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Old 22nd June 2013   #73
Colin the Bald
 
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......and aero helmets are irrelevent on anything other than a dragstrip!
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Old 22nd June 2013   #74
PiemelPiemel
 
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no.
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Old 22nd June 2013   #75
mdcc_testerdonor
 
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It's probably true that many people who haven't been to a wind tunnel or done extensive field testing are getting no more benefit from long-tailed helmets than they would get from shaving their heads
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Old 22nd June 2013   #76
Colin the Bald
 
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^Amen. Note to self: must rebuild TT bike and tape ears down, aero head supplied naturally, talent less so.....
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Old 22nd June 2013   #77
PiemelPiemel
 
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It's about priorities and proportional gains innit. If your tuck is shit, fix that first because a shit tuck destroys more aero than a helmet can fix. In the same way, assuming your tuck is ok, not having an aero helmet and shoe covers destroys more aero than a frame can fix.

Assuming the guy in the picture has heart & lungs and an ok tuck, the next step for him would be shoe covers and an aero helmet, not an aero frame. If he does not have heart & lungs and his tuck is shit, his bike is already overspecced.
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Old 22nd June 2013   #78
PiemelPiemel
 
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Quote:
Originally Posted by mdcc_tester View Post
It's probably true that many people who haven't been to a wind tunnel or done extensive field testing are getting no more benefit from long-tailed helmets than they would get from shaving their heads
Assuming this is true (which I like to do with your statements), it's still foolish to engage in competitive cycling without a helmet. An aero helmet* is going to be considerably more aero than a normal road helmet, with or without windtunnel tuning.

*Not necessarily the pointy type but also the smooth round ones.
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Old 22nd June 2013   #79
mdcc_testerdonor
 
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Quote:
Originally Posted by PiemelPiemel View Post
it's still foolish to engage in competitive cycling without a helmet
>>>>>>>>>>>>>>>>>>http://www.lfgss.com/thread1525.html

Time Trialling is a road ride plus timekeepers, it doesn't really have any relationship to the kind of competitive cycling where your argument might be valid.
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Old 22nd June 2013   #80
mdcc_testerdonor
 
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Quote:
Originally Posted by PiemelPiemel View Post
An aero helmet* is going to be considerably more aero than a normal road helmet
Might be true, but is it more aero than a shiny dome? The testing I've seen suggests not, and that only a properly selected and fitted pointy hat can beat a shaved head. If you have a shock of lustrous wavy locks, you're probably better off squashing them under a styrofoam bowl.
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Old 22nd June 2013   #81
Oliver Schick
 
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What does Tuck have to do with it?

http://1.bp.blogspot.com/_nYmWjp9KBI...OfSherwood.jpg
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Old 22nd June 2013   #82
Oliver Schick
 
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Quote:
Originally Posted by mdcc_tester View Post
It's probably true that many people who haven't been to a wind tunnel or done extensive field testing are getting no more benefit from long-tailed helmets than they would get from shaving their heads
I thought field testing was only important for cyclo-cross and grasstrack?
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Old 22nd June 2013   #83
mdcc_testerdonor
 
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Originally Posted by Oliver Schick View Post
What does Tuck have to do with it?
He is demonstrating an advanced variant on the shaved head approach, using a strip of hair as an aerodynamic trip to delay boundary layer separation.
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Old 23rd June 2013   #84
Colin the Bald
 
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....and I swear he was off at number 19 on the last TT I rode.

To summarise: twist your body into the right(ish) aero shape, shave your head (unless you're me) and nowt else matters very much.

*blue touch-paper lit*
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Old 23rd June 2013   #85
umop3pisdndonor
 
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Aren't people starting to wonder whether shoecovers actually save any time? Increase in A vs (alleged) decrease in D.
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Old 23rd June 2013   #86
Gaston Fr
 
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wrong tread ?

http://www.google.fr/imgres?imgurl=h...ed=0CDAQrQMwAg

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Old 23rd June 2013   #87
umop3pisdndonor
 
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That is a comically large helmet.
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Old 23rd June 2013   #88
soserious
 
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Just thought I'd pop mine in here, not rode any TT fixed yet but would love to have a bash :-)
Attached Thumbnails
image.jpg  
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Old 23rd June 2013   #89
ncjlee
 
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Quote:
Originally Posted by umop3pisdn View Post
That is a comically large helmet.
Obligatory that's what she said comment.
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Old 24th June 2013   #90
hippy
 
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Originally Posted by mdcc_tester View Post
It's probably true that many people who haven't been to a wind tunnel or done extensive field testing are getting no more benefit from long-tailed helmets than they would get from shaving their heads
Regardless of how it tests, I'll stick to the sperm hat. At least you don't have to walk around looking like a skinhead the rest of the time.
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Old 24th June 2013   #91
hippy
 
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Quote:
Originally Posted by umop3pisdn View Post
Aren't people starting to wonder whether shoecovers actually save any time? Increase in A vs (alleged) decrease in D.
I'm pretty sure according to Alex Simmons testing for one of his rider's attempts at the Masters Hour record, they are faster.
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Old 24th June 2013   #92
Object
 
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This must have been posted previously?
Link
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Old 24th June 2013   #93
'dandonor
 
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Quote:
Originally Posted by umop3pisdn View Post
Aren't people starting to wonder whether shoecovers actually save any time? Increase in A vs (alleged) decrease in D.
stupid question time, what is A and D? Drag?
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Old 24th June 2013   #94
hippy
 
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Area and Drag

Overshoes increase the frontal area - you're adding material to your shoe but they should decrease drag by making the whole unit slippery.
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Old 24th June 2013   #95
hippy
 
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Maybe I lied.. looking at a forum post Alex Simmons says:
"Using lycra booties over shoes is not always more aerodynamic than not wearing them. One should do their aero testing..."
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Old 24th June 2013   #96
Ordinata
 
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So wearin all that 'speed gear' is fo kicks?
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Old 24th June 2013   #97
hippy
 
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Originally Posted by Ordinata View Post
So wearin all that 'speed gear' is fo kicks?
No.
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Old 24th June 2013   #98
Ordinata
 
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Well if I lose the speed socks, sperm hat, shave my heed and legs and go out in my underpants I would be just as fast?*

*Thats what I understood.
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Old 24th June 2013   #99
_dan_donor
 
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surely the amount of area added by an overshoes which is 1mm thick is completely negligible?
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Old 24th June 2013   #100
hippy
 
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It always 'depends' but I always wear a helmet and aero helmets ARE faster than normal road helmets so there's that one answered. Shaved legs might be faster and they look better so there's that one answered. Overshoes might be better - they might not, the difference isn't going to be much. I wear them although I couldn't adjust my shoes yesterday so my foot went numb which has more of a negative effect than the positive aero benefits I may have received. I believe skinsuit materials have tested faster than skin and they offer some compression so probably faster. You also don't break any indecent exposure laws.
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