Author Topic: Fork and Frame Choices  (Read 4027 times)

0 Members and 1 Guest are viewing this topic.

Offline HillClimber

Fork and Frame Choices
« on: October 11, 2011, 10:38:56 pm »
Hello,

I am new to touring and setting up a steel 29er mountain frame.  I am interested in the effects of fork rake on stability and handling.  I currently am using a steel fork with a rake of 38mm.  The current fork is strong and comfortable and I have been happy with the handling of the bike unloaded.  But it has no braze ons for fenders or racks.  I was considering a Salsa Fargo fork with 50mm of rake as it has all the braze ons and fender mounts.  Although the top tube is longish and BB higher on my Fisher Ferrous, I did not think I would have to get a whole new frame (like the Fargo) for touring. Would I be better off with the current rake that I have or be ok with the Fargo fork?  I can get a new version of the fork I already have with full compliment of braze ons but would be pricier going this route. Right now I am not sure if I am going to do bike packing or fully loaded.  I believe I will be happier bike packing.  Any advice is appreciated.


FredHiltz

  • Guest
Re: Fork and Frame Choices
« Reply #1 on: October 12, 2011, 06:13:22 am »
Rake is just one of many factors affecting stability. http://www.google.com/search?q=bicycle+fork+rake+stability&ie=UTF-8 finds several good articles.

I would start with the current frame, adding clamps as necessary for the accessories. If you like touring, then a real touring bike will add to the enjoyment, and you can move the accessories to it. But that's a lot of money to spend before you know you will get good use of it.

Fred

Offline DaveB

Re: Fork and Frame Choices
« Reply #2 on: October 12, 2011, 08:49:00 am »
The articles Fred referenced will explain the relationship but, in brief, less rake means more trail and more trail means slower and less touchy steering.  Going from 38 to 50 mm of rake will "speed up" the handling of your bike significantly and that's the last thing you want on a tourer. 

Offline whittierider

Re: Fork and Frame Choices
« Reply #3 on: October 12, 2011, 12:34:26 pm »
The head tube angle and the fork rake work together to produce "trail," and these work together to determine stability.  The Rivendell Reader, issue #31 from Jan '04, had a report on some experiments Rivendell did.  They made a special fork with long, horizontal dropouts, so the wheel could be moved forward and back.  They did not have a way to change the head tube angle so easily, but from what they did try, the writer says about trail: "The biggest difference came out in no-hands riding-- the low-trail bikes were easy to ride at low speed, where the tons-o'-trail bikes were hard; and at high speeds it was just the opposite."

There's also the matter of how far forward from the steering tube you put your hands on the bars (involving the bar reach and the stem length) affecting the handling, as well as the practical matter of toe overlap.

Then you also have to weigh the effects of panniers and other loading.

Offline DaveB

Re: Fork and Frame Choices
« Reply #4 on: October 14, 2011, 09:46:18 am »
"The biggest difference came out in no-hands riding-- the low-trail bikes were easy to ride at low speed, where the tons-o'-trail bikes were hard; and at high speeds it was just the opposite."
This makes sense since at low speed (walking speed) the bike must react quickly to steering inputs since it isn't moving far in a given time.  At "high speed" (normal riding speeds, say 10 mph and above) the longer trail gives slower and more stable handling and isn't as fast to react to minor steering inputs.