Steel fork query

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531colin
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Location: North Yorkshire

Re: Steel fork query

Postby 531colin » 21 Apr 2015, 8:59am

Touring geometry in this case being 71 deg head, 55mm offset http://dawescycles.com/wp-content/uploads/2015/02/Touring-Geometries.pdf
Its a really long fork due to the strange upward extension of the unicrown under the crown race..http://dawescycles.com/product/galaxy-plus/
Its a welded unicrown, it isn't a case of brazing a new steerer into a cast crown. If the existing 1 1/8" steerer isn't internally butted at the bottom, then a 1" steerer will slot right in.... I can't remember which bit of the lump forms the crown race seat, but the builder will have to produce a new seat.
Being a disc fork, its the sort of thing that will try to break your wrists on a bumpy road....I think thats fashion, rather than "high end". 631 blades brazed into a nice crown will give you a nice comfortable fork......caveat...I'm 11 stone...somebody weighing half as much again will get a bit of flex out of these behemoths

I'm not against fitting different forks to modify the steering geometry, i am running 2 bikes like that. however, I think you need to go into it with your eyes open before spending money, we have already had one surprise on this thread, somebody said bikes this age were pretty laid back geometry, it turns out its 73 deg parallel....just the sort of thing i would put a long fork (with a small offset) on to calm it down a bit, but then i know exactly what sort of steering geo. i like....getting there by luck is not an option for me.

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bigjim
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Joined: 2 Feb 2008, 5:08pm
Location: Manchester

Re: Steel fork query

Postby bigjim » 21 Apr 2015, 9:03am

Roger that seems a very expensive way to run a classic bike. The frame is brand new untouched from the factory in the 1980s. It has never been built up so I'm reluctant to mess with it. I already own the bike pictured which is also mint but not exactly my size so may sell it on. it's possible to buy a rough Royal on e-bay for about £100 so I may hang fire to do that and respray the fork myself. Forks with long steerers seem pretty rare. I'm quite happy with rim brakes.

Thanks. I've put that fork on my watch list. Though I was trying to avoid canti brakes.

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breakwellmz
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Joined: 8 May 2012, 9:33pm

Re: Steel fork query

Postby breakwellmz » 21 Apr 2015, 10:36am

I see the fork i highlighted has now gone, was it you?

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bigjim
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Location: Manchester

Re: Steel fork query

Postby bigjim » 21 Apr 2015, 10:46am

breakwellmz wrote:I see the fork i highlighted has now gone, was it you?

No. Not guilty. I thought it was a bit pricy anyway with postage. Amazing what old forks fetch. Will have to stick a couple up. I've paid less for complete bikes. :)

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recordacefromnew
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Joined: 21 Dec 2012, 3:17pm

Re: Steel fork query

Postby recordacefromnew » 21 Apr 2015, 11:18am

531colin wrote:I think you need to go into it with your eyes open before spending money, we have already had one surprise on this thread, somebody said bikes this age were pretty laid back geometry, it turns out its 73 deg parallel....just the sort of thing i would put a long fork (with a small offset) on to calm it down a bit, but then i know exactly what sort of steering geo. i like....getting there by luck is not an option for me.


I agree. Assuming 700c 30mm tyres, 45mm offset (which is common, recent road forks are usually within 40mm and 50mm) will deliver 52.6mm trail for 73 degree headtube. For reference nearly all large Trek road frames have a 55mm trail, and typically deviation outside the 50mm to 63mm range is not recommended.

Since every 10mm reduction in A2C will reduce trail by 3mm resulting from increasing headtube angle by 0.5 degree, and every mm reduction in offset will increase trail by essentially the same amount, typical 700c forks 10mm shorter than original would need to have a 40mm offset to deliver 55mm trail, and a long pair of forks per original, likely 382mm A2C or thereabout with 40mm offset, would deliver a still reasonable 58mm.

andy65
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Re: Steel fork query

Postby andy65 » 21 Apr 2015, 10:40pm

Brake drop could be a problem at the rear with a 700c wheel. 4 mm doesn't sound a lot but if the clearance is generous with a 27" wheel then you could struggle to source a brake calliper with enough drop.

drossall
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Joined: 5 Jan 2007, 10:01pm
Location: North Hertfordshire

Re: Steel fork query

Postby drossall » 22 Apr 2015, 12:04am

For what it's worth I've got some SJS forks that I never used or fitted - they are still packaged. Not sure they are what you want though (and not sure what length the fork column is - would need to measure it).