Advertise on Bikeforums.net



User Tag List

Results 1 to 9 of 9
  1. #1
    CycleManiaque karlkras's Avatar
    Join Date
    Jan 2007
    Location
    Hillsboro, OR
    My Bikes
    Pinarello Prince, Diamondback Podium 7, Focus Izalco Tria 1.0, Surly LHT, Raleigh Technium, Brodie Romax
    Posts
    66
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Fork rake... does 2mm make a significant diff?

    Hi,
    I'm facing the reality that I may need to replace my current threadless steel chromed fork with a carbon model since the current (bought used with the frame) has been cut too short for me. I'm guessing this had originally been a threaded conversion gone bad. Too bad too, this is a pretty cool older Pinarello frame...
    Anyway, this is a 1" steerer, and is measured at a 45mm rake. Wheel on, there's still a fair amount of space between tire and fork. Given this, would purchasing a replacement spec'd at 43mm work for me? or is this a big difference? Also, are there other factors I should be concerned with in determining the proper replacement fork? I'm aware that the steer length is important, I'm only considering 300mm in length so I avoid the problem that I have now.
    thanks,
    Karl

  2. #2
    Senior Member Nessism's Avatar
    Join Date
    Jun 2004
    Location
    Torrance, CA
    My Bikes
    Homebuilt steel
    Posts
    2,324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The reduction in rake will increase the trail slightly slowing the steering. Key word here is "slightly" - I doubt you will notice the difference. A bigger factor is trying to match the fork length. Carbon forks are typically longer than lugged steel forks so when you install the new fork it will raise the front end of the bike some which will further slow steering. It's all a mater of degree and again you may not notice. If you do decide to go forward with the fork swap I suggest that you try to find one that's on the shorter side of average to ward off any issues.

    http://www.sheldonbrown.com/rinard/forklengths.htm

    Good luck.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  3. #3
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,018
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    After selling my wife's bike I found myself with an extra Ouzo Pro fork exactly like the one I had installed on my Trek except it was a 40mm rake instead of the 43 on the Trek. I decided to try the 40 because I thought I would like more trail. Actually I was surprised that I could feel a significant difference, fut after a couple of rides I was fully adjusted and wasn't sure which fork I liked better so I left the 40 on the bike and sold the 43. So I would say that you will feel a difference, not only a difference in trail but also a difference in material. I think I would probably prefer a 43 to a 45 or the longer fork arms because of the increase in trail.

    Al

  4. #4
    In beaurocratic limbo urbanknight's Avatar
    Join Date
    Mar 2006
    Location
    Los Angeles, CA
    My Bikes
    Specialized Allez, K2 Razorback
    Posts
    22,457
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I switched from a 45mm to a 43mm rake when my carbon fork was marginalized by a crash. Aside from a little more toe overlap, it seems a little more twitchy, but it still handles fine. I did have to readjust the saddle fore/aft due to the slight change in geometry.
    "Well, I guess you can cut the arts as much as you want... Sooner or later, these kids aren't going to have anything to read or write about." (Richard Dreyfus as Glenn Holland)

  5. #5
    Senior Member Surferbruce's Avatar
    Join Date
    Jul 2004
    Location
    Los Angeles/Aveyron France
    Posts
    5,308
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    more trail should make a bike less twitchy right? or am i wrong?

  6. #6
    Senior Member Nessism's Avatar
    Join Date
    Jun 2004
    Location
    Torrance, CA
    My Bikes
    Homebuilt steel
    Posts
    2,324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Surferbruce
    more trail should make a bike less twitchy right? or am i wrong?
    You are right!
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  7. #7
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,018
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Surferbruce
    more trail should make a bike less twitchy right? or am i wrong?
    You are correct, at least for normal riding speeds.

  8. #8
    In beaurocratic limbo urbanknight's Avatar
    Join Date
    Mar 2006
    Location
    Los Angeles, CA
    My Bikes
    Specialized Allez, K2 Razorback
    Posts
    22,457
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Surferbruce
    more trail should make a bike less twitchy right? or am i wrong?
    That's what I've heard, but I swear the shorter wheelbase seems to make my bike more twitchy. Either way, 2mm didn't make a big difference. It "felt" different, but rides just fine.

    btw I never did understand the concept of trail. Is it because the axle is behind the handlebar? Aside from that, the fork extends the axle forward from the headtube, so I never understood how that could be "trail"?

    EDIT: nevermind, I get it now. I looked it up on wikipedia and realized that the headtube line is angled but the line for the axle is vertical, so they intersect and the axle point is then trailing.
    Last edited by urbanknight; 05-21-07 at 09:17 AM.
    "Well, I guess you can cut the arts as much as you want... Sooner or later, these kids aren't going to have anything to read or write about." (Richard Dreyfus as Glenn Holland)

  9. #9
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,018
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by urbanknight
    That's what I've heard, but I swear the shorter wheelbase seems to make my bike more twitchy. Either way, 2mm didn't make a big difference. It "felt" different, but rides just fine.
    I read somewhere that increasing the trail can make a bike feel more twitchy at slow speeds, but more stable at high speeds. I think that may fit the experience I had with my Trek. My Colnago has a lot more trail than my Trek due to the more laid back head tube angle and it is way more stable feeling even with a 43mm rake offset as compared to the 40mm on the Trek. My perception is that the HTA is more critical than the rake offset.

    Al

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •