Thursday, 24 March 2011

About those Lambert / Viscount Death Forks


The amount I have written on this blog so far without mentioning ‘death fork’ and Viscount or Lambert in the same sentence is probably a record.  Now I will say a bit about it.  Despite dire warnings about ‘death forks’ on the Internet, there are very few facts to back them up.  

To begin at the beginning, even the earliest Lamberts (like my 1972 gold plated Professional Grand Prix) had a cast aluminium alloy front fork (the part that holds the front wheel).  As with most traditionally constructed bikes, this was attached to a steel ‘steerer’ - the part that turns in the headset bearings and into which the stem holding the handlebars fits.  In the early 1970s aluminium forks were extremely innovative if not unique.  The idea was (of course) to reduce the weight of the bike.  Incidentally the feel of the bike was changed, because aluminium behaves differently to steel under stress.  (The modulus of elasticity is different.)  Some people don’t like the ‘feel’ of ally forks.

Unfortunately, there were accidents resulting from sudden catastrophic failure of Lambert forks.  If you are travelling at any speed, the failure of anything at the front of the bike - fork, wheel, stem or bars - is frightening and potentially very serious.  I know of a friend of a friend who experienced Lambert fork failure and was scarred as a result.  So I don’t doubt the reality of an ‘injury fork’; even if no-one was killed.  The number of forks that broke has been reported as less than 1% of the 30,000 or so bikes made with the ‘death forks’.  Unacceptable, but not as bad as some would have you believe.

Failure seems to have been associated with the method of attaching the fork to the steerer.  The first picture shows this.  The crown of the forks had an integral extension that fitted into the steel steerer tube.  To make this joint as firm as possible, the steerer tube was heated, making it expand, before fitting it over the crown extension.  When it cooled, it contracted and gripped the alloy part firmly. A couple of dowel pins (probably spiral pins like these) were inserted in holes running front to back.  This is the first version of the alloy fork.  The second version was similar but had the pin put through from side-to-side.  This might have been an attempt to reduce stress concentration in the part.  However, both these versions were known to fail, usually as the result of an impact of the front wheel with a kerb or other immovable object.  Breakage occurred near the base of the fork extension.  The article accompanying these diagrams calls these two types the Lambert forks and the third version the Viscount one.  The article is by Yamaha so this may just be a device to distance Viscount from the Lambert failures.  My other Lambert bike has a type three fork, although a replacement - perhaps a partial product recall - cannot be ruled out.
The third version of the forks, presumably introduced because of continuing failures of the earlier versions, brought in a separate steel crown extension.  This screws into the crown of the forks and is secured with Loctite™.  The mounting bolt for the front brake passes through the whole assembly and gives further security.  The upper part of the steel insert fits into the steerer and is secured with a pin.  Information on the Internet is that the third type is very reliable.  They are still found on Viscounts that come up for sale, (they were only fitted to the top of the range Aerospace Pro), which have notched up considerable mileages. They were used on the works team bikes in road racing and by others for cyclocross.  See this Cycling Touring Club (CTC) forum for more details.  Nevertheless, at some point in the late seventies, the new owners of the marque, Yamaha, decided to mount a full-scale product recall of all alloy forks and free replacement with steel (Tange?) ones.  I think this must have been a response to continuing bad publicity / bad mouthing about the Lambert forks and the difficulty of telling one type from the other.  It is clear that Lambert did not handle the fork problem well and, despite the efforts of Trusty/Viscount to sort out this and the early quality problems, its shadow was still hanging over the bike into Yamaha times.

It is actually quite easy to tell if your bike has a third version fork or one of the earlier ones.  First check with a magnet or by inspection that you have alloy (non-magnetic) rather than steel forks.  If the latter, you need worry no further.  Most Viscount steel forks have traditional square shoulders with lugs.  Some have sloping shoulders and look superficially like the alloy forks.  Alloy forks were always supplied unpainted; steel ones were painted and often (depending on the model) half chromed.

To check alloy forks, remove the front wheel and the front mudguard (fender) if fitted.  Ideally, turn the bike over to get a good look.  If the underside of the fork crown - i.e. between the ‘legs’ - is smooth alloy; then you have an early version.  I would not suggest that anyone rides a bike with one of these, other than for a sedate Sunday afternoon turn around the park.  If you can see a circular indentation in the centre of this part of the forks that you can’t clean away (!), test it with a small magnet, such as a round fridge magnet.  You should be able to detect that in the centre there is a magnetic steel part, whereas the rest of the fork is non-magnetic.  I am quite happy to ride a bike with an alloy fork of the third kind on a daily basis, as I might with any other twenty-five year old component, but I cannot advise readers what to do.

Finally, in case people think that Lambert and Viscount are the only bikes that have ever had problems, see this recall notice for forks used on a Cervelo bike.  As it says ‘The forks steerer can break during normal use.  In some circumstances this can cause the rider to lose control, fall and suffer serious injuries’.  Might have been written about the Lambert ‘death fork’.

Thanks to the careful reader who pointed out that the Trusty factory was in Bilston, a former steel-making town about 4 miles south-east of Wolverhampton, not in Birmingham as I said.  At least I got the region right (West Midlands).

7 comments:

  1. Hooray! A half-hour of internet searching as to whether or not my trusty Viscount includes the not-so-trusty "Death Fork" ended, happily, here at your site: "painted and often (depending on the model) half chromed", that's my fork alright. Also, the magnet test. Earlier I'd asked my roommate if he could tell if my fork was aluminum or steel, both of us sort of looked at it and scratched our heads. Then I read your blog and the suggestion of the magnet test. D'oh! Anyways, thanks again very much. Going out for a ride to celebrate!

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  2. I grabbed a magnet from the fridge, ran down to the garage and checked the Viscount I bought last night. It stuck and I literally danced for joy, because I love the feel of the bike and it was only $100!

    Thank you so much for this detailed post!

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  3. Hey there! So glad I found this blog! I just picked up (what I assume is) an early 70s Lambert 15-speed. Got it on craigslist for $35. It's in pretty bad shape, but I'm excited to work on it. Anyway, I was hoping you could help me out with a little history/identification of this particular model... inconveiniently, the frame has been painted black. Where the paint is chipping reveals a beautiful orange on the head tube and seat tube and maybe silver everywhere else. Lots of lambert branded components. Interestingly, there's a Brooks saddle and Campagnolo seat post clamp. Suntour derauliers too. Oh and the fork has a Magny emblem on it (is that a characteristic of the Death Fork?) Anyway, any help or thoughts on what's stock or anything about this model's history would be awesome.

    Photos: http://www.flickr.com/photos/sambotdotcom/sets/72157627894888121/
    Thanks!

    P.S. Feel free to use any of the photos if you want to blog about this find!

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  4. Hi All,
    I acquired a Lambert frame & forks complete with chain set, about 12 yrs ago on returning to the sport. The owner was keen to point out the dangers of those forks, but was also kee to re-assure me that the ones in this frame were the later "modified" version. Having seen the picture above, & the pictures on the link to the Sheldon Brown article, I am satisfied that I have the Mk III versions, and have covered a few thousand miles on them, including (in the early days) riding the odd club 10 and 25-mile time trial. The bike was stored up about 7 yrs ago, but has seen the light of day on the occasional Sunday morning liesure ride (1-2 hrs) in the interim. I have recently re-built it, using as much of the original equipment I owned, & could could find. The bike handles just like any other 1970's design, smooth & predictable, but arguably safe with those forks in it. I am 11st. (150lb.), & I don't put excessive loads through it. Will give an a/c of the rebuild sometime in the future, including some of the wheezes I utilized to get an extended life out of the odd worn out component, plus a range of 21 useful gears using "period" equipment.
    HTH

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    Replies
    1. Would you be looking for a genuine complete Viscount-Lambert Gold Edition bike?
      Contact me directly at: ccm4104@yahoo.com for pictures and specs

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  5. i just pulled my viscount sebring from under my house. I bought it in 1976 for Aud $250.00
    It is in original condition and needs some attention. I am going to restore it as it has all the great features of a new bike. Sam
    Melbourne Australia

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  6. We have an investigation about that fork, page 68-72 (Sturmer) http://forum.ctc.org.uk/viewtopic.php?f=1&t=21010&p=654658#p654658

    Please let me know if you have any information of good quality photos

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