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fork dimensions A and B ?

Old 06-23-18, 01:11 PM
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dave25
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fork dimensions A and B ?

Looking to buy new fork, can you tell me what those two dimensions represent ?

Point Trekking-Fork - 28" - A - 1" / 230 mm - B - 70 mm
Point Trekking-Gabel - 28" - A - 1" / 240 mm - B - 130 mm
Point Trekking-Fork - 28" - A - 1" / 185 mm - B - 70 mm
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Old 06-23-18, 02:27 PM
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"A" and "B" are generic terms not specifically bike ones. In this reference "A" might be the steerer's length and "B" might be the threaded top portion of the steerer. Really though more initial data reduces the guessing we can only do at this point. Andy
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Old 06-23-18, 02:56 PM
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need: crown race seat to axle center line

and fork Offset/rake from steering tube center axis line to axle center line .

and then wheel radius to the ground plane, of the built bike.

a line thru the steering axis will cross a plumb line down from the axle.

that is your trail , the distance between those 2 lines ,
measured on the ground plane.. in MM.
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Old 06-23-18, 04:17 PM
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I found the listing your looking at - while I agree it is likely about the steerer, it really doesn't say. Contact the vendor.
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Old 06-23-18, 10:30 PM
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So with more time later I did a search and also found what I believe to be the website listing these forks. I see they are threaded. I also see a large amount of threads, that portion is fairly long. So I suspect my initial suggestion is likely correct.

But I also warn anyone who is installing a replacement fork that has a lot of threaded length. Make sure that the wedge of your stem sits below the lower end of the steerer's threads. If not then the outward pressure that the stem wedge places on the steerer's insides can cause the weakened and full of stress risers threaded section of the stem to crack. Since this will be out of sight of the rider the usual first indication of this is when only the cables are what's holding the fork/ft wheel onto the rest of the bike Andy
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Old 06-24-18, 02:56 PM
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Yeah I looked more on the website on some other forks it is mentioned that A = shaft and B = thread.

My bike has head tube less than 130mm. I think this fork would be ok ?
Point Trekking-Fork - 28" - A - 1" / 185 mm - B - 70 mm


If threaded part will be to long is it ok to cut it off ?

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Old 06-24-18, 03:06 PM
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Originally Posted by dave25 View Post
Yeah I looked more on the website on some other forks it is mentioned that A = shaft and B = thread.

My bike has head tube less than 130mm. I think this fork would be ok ?
Point Trekking-Fork - 28" - A - 1" / 185 mm - B - 70 mm


If threaded part will be to long is it ok to cut it off ?
If the unthreaded part is 185mm long, and stack height for headsets is around 40mm, do you have someone to cut more thread?
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Old 06-24-18, 03:15 PM
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I the whole steerer is 185 mm, I cant post links, this is for other fork from the same website:

Bike Fork 20" Thread black 22,2,Shaft 240mm/Thread 130mm

Size • 20"

Shaft
Outer • 1" / 25,4 mm
Inner • 22,2 mm
Steerer • 240 mm
Thread • 130 mm

.......................

if headset is 130mm + 40mm then I would need to cut about 15mm ?

Last edited by dave25; 06-24-18 at 03:21 PM.
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Old 06-24-18, 06:14 PM
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For common 1" threaded headsets about 1" of threads is enough for the threaded parts to fit and for the bearings ability to be adjusted. Not a hard number, just what often is the case. It's easy to measure how much threads your specific bike/headset needs. It's this number that you should know and be working with when sourcing a fork. The first choice is setting dimensions to duplicate is to measure the actual parts already in use. Anything else brings the danger of false assumptions to the party. Like what does a listing mean by "A" when they don't define "A".

This next is an example of what dimensions you need to heed (dependent on what you call a headtube length)- HT + HS stack - 1 or 2mm = steerer length (crown seat to top of threads). 130 + 39 (classic Campy HS height BUT not your HS stack?) - 2 = 167mm steerer. The above fork you describe is then 240 - 167 = 73mm of un needed length. 130mm thread - 73mm un needed length = 57mm of remaining thread. This will work but note my earlier warning about having the steerer's threading overlap with the stem's wedge location, for safety the threads need to end above the stem's wedge. So how deep into the steerer will your stem be? Note again these numbers are either taken from your posts or are approximates of your real ones. Andy
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Old 06-25-18, 11:54 AM
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Thank you very much.
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