Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Increasing trail?

Reply

Old 03-05-11, 07:57 PM
  #1  
Mxfarm
Senior Member
Thread Starter
 
Join Date: May 2010
Posts: 87
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Increasing trail?

Have a late 80's Battaglin - I like the bike and really have no desire to change. Have a lot of miles on it. However it is very "twitchy". You cannot take both hands off the bars - period. Above 30 mph - you have to pay attention - above 35, it's no fun @ all.

It has a 75° HTA, and (about) 47mm rake/fork offset and trail of about 40mm. 700c x 25mm with quite a bit of wear.

So my question is - if I put a fork in it with - say 43-44mm of rake that should get my trail up to 45mm or so. Will that 5mm be enough to take some of the abruptness out of the bike with a 75° HTA?

I primarily ride pleasure/recreation. Rode just over 3000 miles last year.

marc
Mxfarm is offline  
Reply With Quote
Old 03-05-11, 08:52 PM
  #2  
rishardh
Senior Member
 
rishardh's Avatar
 
Join Date: Jun 2008
Location: North Texas
Posts: 427

Bikes: Kestrel Talon; Giant NRS Air; Litespeed Tuscany; Burley Rivazza; Cerverlo RS; BMC SLX01; Litespeed C1r, Merckx Corsa 01, Schwinn Traveller, Brompton M6L

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
I have tried to understand the pros and cons of more vs less trail and it still confuses me. I am too interested to see what others have to say.

From what I understand less trail translates to twitch ride at slow speeds and easy turning at high speeds. More trails translates to steady ride at slow speeds and hard to turn at high speeds. I think it all has to do with how quick the front wheel turns when the bike is tilted.
rishardh is online now  
Reply With Quote
Old 03-05-11, 10:18 PM
  #3  
vision646
Senior Member
 
vision646's Avatar
 
Join Date: Dec 2010
Location: Tucson, AZ
Posts: 241

Bikes: Campania Challenger

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I don't know what you guys are talking about but I also have some high speed twitching. During my ride I reached 40mph coming down a mountain and there were some times when I felt the front wheel twitching, got kinda scary but it was still fun .

What I'm trying to say is that I'm attaching myself to this thread in order to to learn something.
vision646 is offline  
Reply With Quote
Old 03-06-11, 12:49 AM
  #4  
531phile 
I'm Carbon Curious
 
531phile's Avatar
 
Join Date: Aug 2005
Posts: 2,194
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
If it can take wider tires, that's one way to increase trail. Put the biggest one you can.

Use this handy dandy calculator: http://yojimg.net/bike/web_tools/trailcalc.php

Trail around 5.4 to 6.1cm is where it's at, yo.

Problem Solved.
531phile is offline  
Reply With Quote
Old 03-06-11, 08:32 AM
  #5  
big john
Senior Member
 
big john's Avatar
 
Join Date: Sep 2005
Location: In the foothills of Los Angeles County
Posts: 11,916
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 174 Post(s)
Somebody, I think it's Cane Creek, has started making an offset headset for mountain bikes which can change the angle by a full degree. I don't know if they have anything that will work with a quill set-up, or if you can convert to threadless and make something yourself. Just a thought.
I like the steep angle myself.
big john is offline  
Reply With Quote
Old 03-06-11, 09:05 AM
  #6  
merlinextraligh
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Posts: 30,246

Bikes: Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er; Calfee Dragonfly Tandem

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 813 Post(s)
Originally Posted by vision646 View Post
I don't know what you guys are talking about but I also have some high speed twitching. During my ride I reached 40mph coming down a mountain and there were some times when I felt the front wheel twitching, got kinda scary but it was still fun .

What I'm trying to say is that I'm attaching myself to this thread in order to to learn something.
What you're likely talking about is the high speed wobbles, which is a different issue from how the bike wants to turn.

Short answer to your problem is put a knee to the top tube when it happens. Long answer is read some of the threads on high speed wobs.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
merlinextraligh is offline  
Reply With Quote
Old 03-06-11, 11:16 AM
  #7  
SpongeDad
Overacting because I can
 
SpongeDad's Avatar
 
Join Date: Jan 2005
Location: The Mean Streets of Bethesda, MD
Posts: 4,552

Bikes: Merlin Agilis, Trek 1500

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Well, my bike has trail of 56mm and it definitely doesn't feel relaxed, and it handles very well at speed in crits. I thought about moving to 60mm trail and someone said I would be able to detect the change at the margins, just not a lot. If you've got you're measurements right, and there's no toe overlap issue, I think you could go with even less rake (I think Edge makes one, but not cheap).

You might be better off going to a custom guy (like Bilenky in Philly) and having him make you a nice chromed steel fork so you could get exactly the trail you want. Probably not that much more expensive than buying a new carbon fork and it'll look so much better on your bike.
__________________
“Courage is going from failure to failure without losing enthusiasm." (Churchill)

"I am a courageous cyclist." (SpongeDad)
SpongeDad is offline  
Reply With Quote
Old 03-06-11, 07:46 PM
  #8  
Brian Ratliff
Senior Member
 
Brian Ratliff's Avatar
 
Join Date: May 2002
Location: Near Portland, OR
Posts: 10,107

Bikes: Three road bikes. Two track bikes.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 37 Post(s)
Every little bit will help, however, 75deg HTA is like that of a track bike; those usually have forks with about 30-35mm offset. 60mm trail is considered by framebuilders to be more or less neutral as far as the balance between responsiveness and stability; most racing frames are built a bit short of this to make them a bit quicker handling. 57mm is pretty common on both road (73deg, 43mm offset) and track (74.5deg, 35mm offset) bikes.

In the early days of cycling, bikes were designed with no trail as it was believed that the wheel "flop" (the need to lift the mass of the bike to straighten out the wheel) made the bike sluggish. Then, gradually trail was introduced as bikes got lighter (negating the effects of wheel flop) and people realized that steering stability came with increasing trail. I read somewhere that early "modern" italian bikes, which is what you have, were sometimes built to be very twitchy.

A good primer on trail, though oriented to track bikes is here.
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter

Last edited by Brian Ratliff; 03-06-11 at 07:57 PM. Reason: added link and corrected info
Brian Ratliff is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Terms of Service