new set of girders almost completed

[peanut]

I bought a set of chromed girders off e-bay for my trike. They had been fitted to a chopped '45' back in the seventies and since that bike had been put back to stock, had been used as an ornament in a guys front room. He even gave me the plush velvet covered pad that had sat under the legs to protect the carpet. I sold on the low apes, but kept the risers and maltese cross mirror.
Despite what I had read about girders, these were very heavy but that turned out to be, once the chrome was stripped off, because they were made from solid bar, not tube or pipe. Further forensic examination showed that the back legs of the girder had been hitting the lower yoke under full extension. The bolts holding the links in had been tightened onto small pellets of lead to set the free play, but the bushes were all worn and much sloppyness was apparent. The spring was of barrel type but the way it was held in was a bit dodgy to say the least, subjecting it to twisting as well as compressive loads. I take on board what Durfee say about barrel springs and the way they work but that shape is about getting more travel without bind in a short space than any clever progression.
Old girders were not as good as early teles because of the damping or lack of it and the unprogressive nature of a short spring working a large unsprung weight over a long distance rather than any natural superiority. Teles, when worn are just as 'bad' if not worse.

Anyway, I decided to fit a Harley single-disc 21" wheel so we split the girder down the middle and widened it to fit - it looked s**t! We then split the wheel down the middle and narrowed that by an inch and then rebuilt it - much better.

At this point we set the girder up in place with the frame at ride height so we could set the rake and trail with the links sitting about level, or at 1/3 travel. Following advice on the web-site, we set trail at 1 inch although I appreciate that that might mean we need a damper at some point.

The problem with most girders is having room in the top for a large enough spring/damper, so we relocated that to below the bottom yoke and we are now making new yokes, links and bushes to put the whole thing back together.

A girder has lots of potential for adjustability and all the other good technical things but my main point for choosing one was because they look fantastic!

[Manky Monkey]

Fantastical beats practical every time as far as I'm concerned!
Photos of the fork re-build please. 

[panthershaun]

according to people in the know a well set up set of girders is far better than either springers or tele's, damned if I can find the tech article I got that from though 

[ByzMax]

Shaun your right. It comes from the chopper builders handbook see drakens links below and gives all the reasons why girders are best.

Morrag. The real reason teles were succesful was cost/ease of manufacture. Many bikes manufacturerr are going back to using girders. Check new BMW bikes.

 

[peanut]

This is one of the e-bay pictures from my original purchase. You can see the piece of plush-covered carpet protector!

[peanut]

and the top with slabby links and three-tonne risers

[Manky Monkey]

Them's jolly shiney. 

[peanut]

Which is why I must have been blinded when I bought them!
The latest part of their rebuild is to make a spindle and spacers that cater for the fact that the locating 'tubes' at the bottom of each leg have been worn to different sizes than the 3/4 inc original axle size. Couple that with a forkspindle made from gas pipe and incorrect geometry from new and I'll bet that old '45' handled like a plate of jelly. If I look carefully I'll bet there are teeth marks on the risers.

[Manky Monkey]

 

[morrag]

If their so good, I wonder why GP race bikes don't use Girders? or off road comp. bikes!the fact is that generally, and for most applications, the traditional Telescopic fork is still the most effective "compromise" when it comes to front suspension on a motorcycle,and it's always a compromise between practicality, suspension travel, and cost effectiveness, and from my Trialling days,on Montesa, Bultaco, Matchless, etc.... believe me I'd go with a set of Ceriani's over any girder design, including Vincent or present day BMW,when negotiating some of the "hairy" drops and climbs that you were required to attempt! something of a case"rose colloured specs" I think, gents, when it comes to girders as practical alternatives, but if you just want to be different, or asthetics are you're bag...........Morrag

[Manky Monkey]

I just think they look cool, which is good enough for me. 

[morrag]

Like I said Mr M, if it's looks what grabs yer!go with it, but better, please...... and to use "chopper" suspension technology to suppory a suspension/handling arguement! well i rest my case. Chopper style is just that, all style, but technically, I dont think so! Morrag

[flc]

Have a look at these not starting an arguement ,but another slant on fork technology, i agree on the style arguement but like all things, advancements in technology and material research have improved a lot of old ideas,
http://www.motorcyclespecs.co.za/bikes/Britten.htm

[ByzMax]

Girders don't have to look like peanuts ones. As far as I understand many of the racing teams are looking at girders of different designs to improve the bikes handling.

For driving over a parked car or rocks/ steep muddy hills i'm sure teles are better and you can see why but It's not just about style/appearance they do in many cases work alot better especially at high speeds and under heavy braking.

But it really don't matter because most of us will never drive fast enough to notice the difference. 

[peanut]

'But it really don't matter because most of us will never drive fast enough to notice the difference.'
and never was a truer word spoken.
fastest bloke I ever saw on track was at a Mallory track day on an ER5, complete with racks. The guy had only been riding for 6 months, almost all as a despatcher and was put up a group in every session until the travelling marshalls just took him out on his own. He had no idea what he was doing, what tyres he had on or how many clicks of what he had on which, but he just blew around everyone.
 I reckon that he had never crashed and so didn't know how to!