what is a track geometry?
05-12-08 | 06:23 AM
#3
Tinkerer since 1980
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From: London
Bikes: Coppi racer, Old school BMX, some random a fixed wheel convertion
I read a good article by Don Walker on track geometry once. Explained the different geometry for different disciplines, some of which were more or less road type geometry. I can't fins it though maybe someone can post a link.
05-12-08 | 06:45 AM
#4
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From: Rocket City, No'ala
Bikes: 2014 Trek Domane 5.2, 1985 Pinarello Treviso, 1990 Gardin Shred, 2006 Bianchi San Jose
Track bikes are designed to be fast on a smooth, banked surface; a place where brakes are not needed and indeed are dangerous to use. Very responsive, twitchy handling.
The things that make a track bike excel on the track make it a poor bike for riding on city streets or out in the country on the open road. Likewise, a road bike isn't built for the track.
Road geometry varies from company to company and from "racer" geometry to "recreational" geometry. The more agressive ones approach track geometry but still have a longer wheelbase and more trail which gives them more stability; a good thing on fast descents down mountains. Time trial bikes are basically track bikes with gears and brakes and aero bars. Touring bikes have even longer wheelbases, more trail, slacker headtube and seattube angles. They are designed to carry a lot of weight and still be stable.
Subtle changes in the tube angles and lengths can greatly affect the way a bike feels and rides so it is a good idea to test ride lots of bikes before deciding on one.
Unless it's a track bike, where only fashion sense rules.
The things that make a track bike excel on the track make it a poor bike for riding on city streets or out in the country on the open road. Likewise, a road bike isn't built for the track.
Road geometry varies from company to company and from "racer" geometry to "recreational" geometry. The more agressive ones approach track geometry but still have a longer wheelbase and more trail which gives them more stability; a good thing on fast descents down mountains. Time trial bikes are basically track bikes with gears and brakes and aero bars. Touring bikes have even longer wheelbases, more trail, slacker headtube and seattube angles. They are designed to carry a lot of weight and still be stable.
Subtle changes in the tube angles and lengths can greatly affect the way a bike feels and rides so it is a good idea to test ride lots of bikes before deciding on one.
Unless it's a track bike, where only fashion sense rules.
05-12-08 | 10:29 AM
#6
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Don Walker, The Truth About Track Bike Geometry
05-12-08 | 10:47 AM
#7
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From: Van BC
Steep twitchy tight track geo def helps u to avoid cars and potholes when riding in the streetzzz
On a normal road frame I'm always plowing into **** because the geo is so slack
Edit: thanks for the article devolution
On a normal road frame I'm always plowing into **** because the geo is so slack
Edit: thanks for the article devolution
Last edited by mander; 05-12-08 at 07:25 PM.
05-12-08 | 09:26 PM
#10
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Don Walker, The Truth About Track Bike Geometry
Originally Posted by Don Walker
The baseline for handling is called neutral steering. This is where the bicycle will handle neither twitchy nor sluggish; it will handle the most stable. This is when the end result of the combination of rake and headtube angle yield 60mm trail. This primarily works for road bikes with the combination of 73.2 headtube angle and 40mm of fork rake (See Illustration Road Neutral). For track bikes it is a headtube angle of 75 degrees and 29mm of fork rake (See Illustration Track Neutral). So, what’s the difference you may ask? For starters, a slack headtube is more inclined to absorbing road shock whereas a steeper headtube is more apt to making a rider feel every bump.
This is one of the reasons why you see most road bikes with slack headtubes and most track bikes with slightly steeper headtube angles. The variables here are wheelbase and front center. When you steepen a headtube angle and shorten the rake, you have effectively shortened the wheelbase in the front of the bike. This may affect the balance of the rider on the bike as well, because one of the handling characteristics is how the rider’s body sits between the wheels. Balance between the wheels is almost as important as the geometry and wheelbase in the handling of the bicycle. Having too much weight for or aft of the bike will most certainly make the bike handle either twitchy or sluggish. For example, if you take a sprint frame and attach aero bars to it and put a rider in the aero position, the bike will certainly be all over the place because there is too much weight forward.
Now, let’s visit the twitchiness ideology. Some twitch is actually a good thing. Why?
If you are in a bunch and someone inevitably crashes in front of you, what do you do? Natural instincts and good handling skills will tell you to go up track (I feel for you if you chose option “B” which is to go down track to avoid impending carnage). You will need a bike that is just twitchy enough to pull this off without becoming too unstable and going down yourself. Now, what I have found works for steering in this situation, and is applied to our 55cm model, is a 74.5 headtube angle and 35mm of rake. This works out to be 57mm of trail, just shy of neutral steering. While it isn’t the prescribed 60mm of trail, it’s just that little bit of twitchiness that is needed for such escapes (see the “Just Twitchy” illustration).
This is one of the reasons why you see most road bikes with slack headtubes and most track bikes with slightly steeper headtube angles. The variables here are wheelbase and front center. When you steepen a headtube angle and shorten the rake, you have effectively shortened the wheelbase in the front of the bike. This may affect the balance of the rider on the bike as well, because one of the handling characteristics is how the rider’s body sits between the wheels. Balance between the wheels is almost as important as the geometry and wheelbase in the handling of the bicycle. Having too much weight for or aft of the bike will most certainly make the bike handle either twitchy or sluggish. For example, if you take a sprint frame and attach aero bars to it and put a rider in the aero position, the bike will certainly be all over the place because there is too much weight forward.
Now, let’s visit the twitchiness ideology. Some twitch is actually a good thing. Why?
If you are in a bunch and someone inevitably crashes in front of you, what do you do? Natural instincts and good handling skills will tell you to go up track (I feel for you if you chose option “B” which is to go down track to avoid impending carnage). You will need a bike that is just twitchy enough to pull this off without becoming too unstable and going down yourself. Now, what I have found works for steering in this situation, and is applied to our 55cm model, is a 74.5 headtube angle and 35mm of rake. This works out to be 57mm of trail, just shy of neutral steering. While it isn’t the prescribed 60mm of trail, it’s just that little bit of twitchiness that is needed for such escapes (see the “Just Twitchy” illustration).
05-12-08 | 10:36 PM
#11
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Oof, that article is overwhelming for someone who doesn't race track.
Am I correct to understand that track geo means less stability and less comfort but quicker handling? Are there any other advantages to it, does it accelerate better?
Am I correct to understand that track geo means less stability and less comfort but quicker handling? Are there any other advantages to it, does it accelerate better?
05-13-08 | 07:02 AM
#13
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From: Toronto/Montréal
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As far as I know, trail on track frame is similar if not higher than on road bikes (which have 55-60mm trail), since most of the time you're going straight. Like was said they have a shorter wheel base, (either because of a steeper HT or shorter chainstays, the latter contributing to frame stiffness) which may contribute to the "twitchiness" feel.
05-13-08 | 07:44 AM
#14
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From: Suburbia, CT
Bikes: Old-ass gearie hardtail MTB, fix-converted Centurion LeMans commuter, SS hardtail monster MTB
"Stability" is a relative term. A chopper is hella stable, but you can't turn quickly. What DW is saying is that 60mm of trail is the most "stable", and can (and often is) reached with track geo. However, he uses 57mm of trail because he feels that the tradeoff of slightly quicker handling is worth it.
05-13-08 | 08:53 AM
#15
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well...I'd say that the track frame puts you in a more 'aggressive' position (for me, with my butt more 'on top' of my legs that behind), and that allows for better acceleration because you're using bigger muscles and keeping your weight on the front end lower than would otherwise be
popping up a wheelie is easier on lax frames than on track frames..wheelies are bad for max accel....though great for max gulliness while accel.
I like this post...
https://www.bikeforums.net/showpost.p...5&postcount=36
popping up a wheelie is easier on lax frames than on track frames..wheelies are bad for max accel....though great for max gulliness while accel.
I like this post...
https://www.bikeforums.net/showpost.p...5&postcount=36
Last edited by teiaperigosa; 05-13-08 at 08:56 AM.
05-13-08 | 09:06 AM
#16
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From: London
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Don Walker, The Truth About Track Bike Geometry
05-13-08 | 11:59 AM
#18
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05-13-08 | 05:50 PM
#19
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I like this post...
https://www.bikeforums.net/showpost.p...5&postcount=36
https://www.bikeforums.net/showpost.p...5&postcount=36
That was the most lucid explanation of geometry I've read so far. I think I get it now.
Would people generally agree with the conclusion that track geometry means better handling / responsiveness at lower speeds and road is better at higher speeds (like, bombing-down-a-hill speeds)?
05-14-08 | 08:44 AM
#21
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I've said it before and I'll say it again:
The only important thing you need to know about track frame geometry is that you can describe it as "agressive," "tight" and "responsive" and wax lyrical the virtues of such geometry on the street.
The only important thing you need to know about track frame geometry is that you can describe it as "agressive," "tight" and "responsive" and wax lyrical the virtues of such geometry on the street.
05-14-08 | 08:50 AM
#22
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From: four 1 OHHH , Maryland
Bikes: nagasawa, fuji track pro
no, as of july 2008, all of the velodromes in the U.S have come together to ban the usage of surly steamrollers for what they state to be "lack of true track geometry." also, as effective currently, all records or times set by riders on a surly steamroller will be voided and erased from the books as the national federation for velodrome racing has said they want nothing to do with steamrollers.
05-14-08 | 08:57 AM
#23
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no, as of july 2008, all of the velodromes in the U.S have come together to ban the usage of surly steamrollers for what they state to be "lack of true track geometry." also, as effective currently, all records or times set by riders on a surly steamroller will be voided and erased from the books as the national federation for velodrome racing has said they want nothing to do with steamrollers.
05-14-08 | 09:32 AM
#24
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Much like carbon bikes. All you need to know is that they are "vertically complaint yet lateral stiff".
05-14-08 | 01:27 PM
#25
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From: Van BC
Thread mvp: jdms_mvp
No. If you open the entire thread that that post is from you'll see there is strong dissent from mr dutret.
YES!
That was the most lucid explanation of geometry I've read so far. I think I get it now.
Would people generally agree with the conclusion that track geometry means better handling / responsiveness at lower speeds and road is better at higher speeds (like, bombing-down-a-hill speeds)?
That was the most lucid explanation of geometry I've read so far. I think I get it now.
Would people generally agree with the conclusion that track geometry means better handling / responsiveness at lower speeds and road is better at higher speeds (like, bombing-down-a-hill speeds)?
Last edited by mander; 05-14-08 at 01:31 PM.