MikeT
new member
Reged: 02/08/04
Posts: 10
Loc: Ontario Canada
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Tom, I was reading your website and on the page on Trail & Effects it ended with this statement - "Track frames are a whole different thing though. If you would like me to, I can get into that. Let me know."
Tom as I'm searching around for a custom track frame I'd be happy to hear your views on this subject. I've had a few custom frames (road & mtb) made in the past so I'm aware of Trail and its relationship to handling but I've never seen an opinion on how Trail relates to a track frame's handling.
If it makes any difference I ride on the new http://www.forestcityvelodrome.ca/index.html with 50 degree bankings and 138 metre laps and any track frame I would order would be a "general purpose" (meaning I don't race!) version.
I'm editing this post to include this - I instruct two Trackskills sessions per week and it's very apparent that the hardest thing to do on this track is to "hold the black line" in the banking while going flat out. Some people do it much better than others. Does Trail have anything to do with this or is it personal skill related to banking geometry?
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Tom_Kellogg
journeyman
Reged: 12/22/03
Posts: 67
Loc: Lehigh County, Pa.
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Mike:
Because I am lazy, and because it has been a long, hard day, I will address your immediate question ...
When it is consistently difficult to hold your bike down in the turns, there are two common causes. First, the design of the track itself can cause the symptom. Essentially, track design that causes this are insufficient banking relative to the turn radius. Trexlertown has this problem, but as you might have guessed, the other factor related to this design issue is the speed of the cyclist. A slow speed eliminates the problem. Therefore, all tracks are designed to be neutral at a given speed, and that speed is chosen by the designer. Trexlertown is neutral at about 25-28 mph, well below race speed. That speed was chosen so that recreational riders could feel comfortable riding the track.
The second cause is low trail. This is what really gets at your question. Even though your track may be the larger problem, it can be largely dealt with by designing the frame for the track and the expected typical speed of the rider. The degree by which we might increase trail on a frame for your track depends on answering those questions.
Does this help? Hope so.
--------------------
Tom Kellogg
Spectrum Cycles
610-398-1986
http://spectrum-cycles.com/
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andyman
new member
Reged: 01/21/06
Posts: 11
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Tom,
I just read your two articles on "forks" and "trail
and effects" and was wondering if you recommend the
Easton EC90 Aero fork? I'm looking for a new 650C,
1-1/8 steerer carbon non-integrated (standard) fork for my recumbent racing bike
with 650C wheels and 72 degree headtube, 57% rear/43%front weight distribution. It looks very similar in geometry to the following link. picture in top right corner of link.
http://www.bacchettabikes.com/jh-CarbonAeroMain.htm
The Easton EC90 Aero is 38mm rake.
Do you recommend a 45mm rake for this setup which
would give a trail of 5.5cm which is closer to the
neutral handling of 5.6cm? The 38 rake would give a
6.2cm trail. I believe Alpha Q Aero fork 650C, now called TS20 according to website gives 37mm rake.
http://www.truetemper.com/performance_tubing/ts20.asp
Although the Easton is lighter, I am leaning toward
Alpha Q (TS20) Aero because I heard it has wider
clearance compared to the Easton and Reynolds forks in case I want wider tires like 28c. After
all you can't get out of saddle on a recumbent going
over bumps like an upright racing bike.
On the other hand I heard that the Alpha fork has a star nut which can creat instability. Is this true?
Another option is the 650C WoundUp, but I heard it is very stiff ride for recumbent such as above picture. Do you still recommend WoundUp in 38mm rake? I believe it comes in 38mm rake.
I also found an interesting article which compares many popular Aero forks. Have you seen this?
http://biketechreview.com/aerodynamics/aero_forks.htm
Thanks for an informative article.
--------------------
Andy
Calfee Tetra Pro Tandem Trike
Edited by andyman (01/21/06 09:13 AM)
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