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 Post subject: AMP F3 forks and 700c
PostPosted: Mon Apr 01, 2013 3:26 pm 
Dirt Disciple

Joined: Wed Mar 03, 2010 8:02 pm
Posts: 46
Location: Sunny Southend-on-sea
Does anyone know if the brake bosses are movable on these forks. There is a small grub screw but the boss seam solid.

I should explain more i've sourced some 700c wheels with a nexus 8 hub to fit to my single speed

As much fun as it is I can understand why gears were invented


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PostPosted: Mon Apr 01, 2013 4:15 pm 
Gold Trader
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Joined: Fri Jan 23, 2009 2:30 pm
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Location: Surrey
I would guess yes, as you often see forks sold without them. It doesn't look as though the legs are stepped to prevent them ring adjusted, but I could be wrong.


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PostPosted: Mon Apr 01, 2013 4:32 pm 
Retro Guru

Joined: Sat Dec 03, 2005 11:16 pm
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Location: Bristol uk
I would recommend a bit of caution here as I seem to recall that there is a maximum tyre size (diameter) that you can use with these forks.
Going too large will lead to the tyre hitting the underside of the crown when the fork fully compresses sending you over the bars and onto your face :? :shock: :evil: :oops:


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PostPosted: Mon Apr 01, 2013 5:14 pm 
Retro Guru

Joined: Sat Jan 24, 2009 7:33 pm
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retrobate wrote:
I would recommend a bit of caution here as I seem to recall that there is a maximum tyre size (diameter) that you can use with these forks.
Going too large will lead to the tyre hitting the underside of the crown when the fork fully compresses sending you over the bars and onto your face :? :shock: :evil: :oops:



you need a minimum of 11mm clearance from the tyre to the underside of the fork crown! just looked on my paper manual for said forks, you can download the manuals here ....

http://www.amp-research.com/download/143/

http://www.amp-research.com/download/144/


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PostPosted: Mon Apr 01, 2013 8:10 pm 
Retro Guru
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Location: Sunny? Devon
While the bosses are removable, I think a form of adhesive is used as a secondary location method, you might need a largish persuation stick to get them to move.


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PostPosted: Wed Apr 03, 2013 3:06 pm 
retrobike rider
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Location: A wretched hive of scum and villainy...
13mm of clearance on an F3 and F4 BLT using a 700c x 25mm tyre, so it's doable. :D

AMP appear to have used an epoxy resin or Loctite Retainer backed up with a grub screw to hold the bosses on.

I've not tried this with mine, but my thinking is that if you unscrew the grub screw (2.5mm Allen key) and heat the boss above around 80º C (Hot air gun), the bonding will go powdery and fail. You could then move the boss up (Providing you've still got the 11mm of clearance to the crown) and align, grub screw and re-bond.

Otherwise, clamp-on bosses are certainly available for the F4 (which have fatter 28.6mm legs), but they might be available for F3 (25.4mm) legs too, from Brion at AMP (ampbikeparts@gmail.com).

There's an ongoing AMP parts order thread here: http://www.retrobike.co.uk/forum/viewtopic.php?f=3&t=247154

Otherwise, you could always forget moving/removing the canti bosses completely and run a disc or roller brake on the front...you'd need an AMP-ISO adapter though... :x

All the best,


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