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Reynolds Fork on a Bianchi Pista

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Reynolds Fork on a Bianchi Pista

Old 12-07-08, 06:16 PM
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danielb89
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Reynolds Fork on a Bianchi Pista

I ride a Bianchi Pista and have recently found a used Reynolds Carbon Fork for relatively cheap. 43 mm rake. Will it fit?
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Old 12-07-08, 07:02 PM
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the pista has a 1" steerer tube.
As long as the fork is a 1", you should be good.

Linking would help.
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Old 12-07-08, 07:23 PM
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also make sure the steer tube is long enough to get the same stem/bar heigth
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Old 12-07-08, 08:49 PM
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It's not ideal - a fork with 43mm of rake has too much rake for the Pista's steep headtube. It will result in a suboptimal amount of trail, less than ideal handling.

Steep headtubes (74deg) and low-rake forks (28-35mm) compliment each other. Raked-out forks (40-45mm) and slack headtubes (72-73) compliment each other. Mixing and matching leads to too much or too little trail.

(numbers are rough, i'm not currently working off of a trail calculator).
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Old 12-07-08, 10:25 PM
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Originally Posted by queerpunk View Post
It's not ideal - a fork with 43mm of rake has too much rake for the Pista's steep headtube. It will result in a suboptimal amount of trail, less than ideal handling.

Steep headtubes (74deg) and low-rake forks (28-35mm) compliment each other. Raked-out forks (40-45mm) and slack headtubes (72-73) compliment each other. Mixing and matching leads to too much or too little trail.

(numbers are rough, i'm not currently working off of a trail calculator).
what is the head tube angle on the pista? i recall reading in the road forum that the caad9 has a steep head tube (iirc 74 or so) and has a rake in the lower 40s.

on my alien ive got a soma threaded fork which is 41 according to soma, the head tube is 74.5 (maybe a little less with the soma fork-more crown clearance) and it rides just fine.
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Old 12-07-08, 11:38 PM
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The head tube angle on the Pistas is 74 degrees on the smaller sizes. I've got a 59cm with a 75 degree head tube angle. The stock fork rake is 28mm. I tried to put a fork with about 35mm of rake on, and it changed my handling drastically for the worse. I've read that some people like it, but I hated it. I wouldn't recommend it.
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Old 12-08-08, 06:06 AM
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Some resources:
The Truth About Track Geometry:
http://www.urbanvelo.org/issue3/urbanvelo3_p44-45.html

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).


Trail Calculator (Excel spreadsheet): http://www.anvilbikes.com/images/1064634020.xls
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Old 12-08-08, 09:17 PM
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I ride a 59cm Pista, which represents one size too small for me.

However, I have very short legs for my height, and the 59cm frame with its sloping top tube lets me stand over the bike safely.

Additionally, in order to get a proper fit to the pedals, I ride with a setback seat post, which puts me a little further back on the bike than normal.

The end result, with a 75 degree head tube and 28mm of rake, gives me a sweet handling bike that feels stable and controllable, and yet seems to read my mind.

Thanks to queerpunk for posting the excerpt from THE TRUTH ABOUT TRACK GEOMETRY.

It made a lot of things clearer for me.
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