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Fork Rake Question

Old 04-05-12, 03:27 PM
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GMM
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Fork Rake Question

Need an replacement fork, dealer says maker has none.

The headtube angle is 72.5 - the original fork rake is 50mm.

Would going with a 45mm rake make any differance in handling?
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Old 04-05-12, 03:42 PM
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unterhausen
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it will matter a little. Is the axle to crown distance the same? Those little changes can add up
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Old 04-05-12, 03:52 PM
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The original fork = 370mm axle to crown
A replacement(Bontrager) would be 371mm at 45mm offset.
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Old 04-05-12, 05:45 PM
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You are increasing the trail. That will stiffen up the steering a little, which you might feel is fairly obvious during sharp turns at low speed. It will also be a little less forgiving of a front load. A handlebar bag will make things a little unstable.
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Old 04-05-12, 06:42 PM
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Originally Posted by unterhausen View Post
You are increasing the trail. That will stiffen up the steering a little, which you might feel is fairly obvious during sharp turns at low speed. It will also be a little less forgiving of a front load. A handlebar bag will make things a little unstable.
+1

You'll be increasing trail by 5mm (from 54mm with original fork to 59mm with the Bontrager fork, assuming 700c x 23c tires).

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Old 04-24-12, 11:54 PM
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Update:

Hey guys,

I checked around, found two reasonably priced forks, ran the numbers and here’s what I came up with.
Based on a 1mm lower stack height.

Original geometry: curved bladed fork
74-degree seat angle, 72.5 degree headtube angle, 370 axle-to-crown fork @ 50mm offset = 54mm trail, 70mm BB-drop.

With replacement Bontrager fork: straight bladed fork
73.85 seat angle, 72.35 headtube angle, 371mm axle-to-crown fork @45mm offset = 59.3mm trail, 69mm bb-drop.

With replacement Ritchey Fork: curved bladed fork
74.02 seat angle, 72.52 headtube angle, 368mm axle-to-crown fork @45mm offset = 59.2mm trail, 70.2mm bb-drop.

The questions are:
1. Do the numbers seem correct?
2. Should I ignore the “altered” seat/head tube angles the replacement forks will produce and simply note the new trail values?
3. Does anyone have any experience with Bontrager or Ritchey forks?
4. How does a straight bladed fork’s ride differ from curved?

The Forks:
http://www.ritcheylogic.com/dyn_prodfamily.php?k=451879
http://www.bontrager.com/model/04037
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Old 04-25-12, 08:35 AM
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1. Yes, but they are all so close, for all intents and purposes, they are the same.
2. See #1, and if you were able to feel the difference in steering with the higher trail (you probably won't) the sensation will be gone after riding for 30 min and you'll forget about it.
3. Two name brands, never had trouble with either of their higher end products.
4. Generally speaking, ride characteristics depend more on materials, blade thickness, and amount of offset than on blade shape. Between these two carbon forks I doubt there would be any appreciable differences.
So get the Ritchey, because I always thought Tom was cooler than Keith

Last edited by Live Wire; 04-25-12 at 08:44 AM.
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Old 04-25-12, 12:13 PM
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GMM- As said before the Bont. fork will change the feel of the steering a bit. The Ritchey for won't make much difference from your origonal. The ST and HT angle changes are pretty minor with all three. Perhaps a little bit of seat set back change with the Bont fork, but 3mm is still a small difference for most people to feel. Maybe the other differences will make your decission for you. Stuff like eyelets, tire to blade clearances, visual style or color. Since I'm a curved blade guy and like the other Ritchey stuff I used I'd choose it (assuming the eyeletts and tire clearances were right). Andy.
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