FF: Forks Modified Steering Stem

[hrdaustria]

There were two bikes with “concentrics”, but I didn’t ask either rider about them. One bike had footrests beveled like Peter Volkers’, or is it the other way around?

good morning,
the bike is mine, used quite a lot on our alpine roads and fairly quick too.
i had troubles with the springs being to stiff for my weigth. just in front if the second stage of the international i fitted the 32 lbs/inch springs from norman as the 36 ones toped out to often. i´m still using my thornton front damper as i found the special avo even in the softest setting to stiff for me. i have not yet tested the 32 springs in combination with the avo damper. i´ve the hydraulic steering damper in use too. the only difference is that i altered the fittings to use needle roller bearings instead of the smal ball bearings.
the handling of the bike is good, a little more comfort to ride compared to my old setup with the thornton and justin mackay-smith´s springs. never experianced a front wobble with this setup.
on quick cornering on rough roadsurface the fork is acting lifelier.
braking has improved as the movement of the fork during braking seems less restrictive now.
michi

 

[greg brillus]

The 36 Ib springs top out because they are too long............. You need to shorten them by small amounts until the "Topping out" does not happen. I have found that the softer springs are too soft even on a Comet, the Thornton shockers are by far the best.........Use a pair of 45 Ib springs with about 20 to 25 mm cut off each and this will be perfect. I'm still installing these kits for folk here down under and getting only positive results.

 

[vibrac]

It would help in all reports if you could state single or twin

 

[greg brillus]

All the bikes I do including singles and twins same 45 Lb springs, only I remove slightly more or less off the length of the springs to suit heavy or light weight riders. The twins will handle a stiffer shocker but the singles need a softer one. The last single I did the rider was about the same weight as me, and I installed an original Armstrong shock, but he felt it was almost too soft, and replaced it with a Thornton he had. Again this was with a pair of the 45 Lb springs with about 25 mm cut off one end on both springs.

 

[timetraveller]

Greg, a question, which if I have asked before I apologise. If you put a cable tie round the inner front spring box, push it up against the bottom of the outer spring box and then go out for a ride over bumpy roads what movement is recorded by the shift in the cable tie. With the set up used here we get about three inches or possibly a little more. That is the limit of the movement controlled by the AVO dampers. There are two thing to consider, the pre-load and the spring rate. The pre-load has to be right to ensure the geometry is working as it should (lower link more or less horizontal with the rider seated) and I try to get as much movement as possible without the system bottoming out.

 

[greg brillus]

It generally uses most of the travel left in the spring cases.......I have only ever chopped about 15 to 20 mm off one machines cases, the lower halves where like a knife edge at the top and jamming on full compression. All other bikes I have left the cases untouched, although I do go to a lot of trouble to make sure they do not bind or jam when fully compressed. I have tried pretty much all springs and shocker combinations........ If you install the springs as they are, the front end will be topped out, there is too much pre-load........... So once the springs are shortened enough for this not to happen, then the front end will easily bottom out on heavy bumps and braking. If people are using the weaker springs, and are happy with the results, that's great, but I will say that it is definitely the shock absorber that is taking up a lot of the load. If you disconnect the front shock absorber and ride the bike, it will readily bottom out without much of a bump and applying the front brakes. The singles will definitely feel softer and better rider comfort than the twins on account of the extra 30 Kg's in weight...........I tried using softer springs on mine and it did feel softer, but would bottom quite easily. Perhaps if I chopped some of the cases down it might handle the softer springs, but I really don't want to do that .........I'm very happy with my bike..........It is at the rear of the bike that the bigger gain would be made to ride comfort, say a fully sprung seat, but I'm still working on that one ........Lets not forget that the main gain from this change to the front end was safety first ........The handling and braking are also significantly improved .......These are the most common comments I get from riders who I have helped out with this mod.

 

[Black Flash]

Just a short update,

As you probably know I am testing my new 8" 4ls brake at the moment.
Yesterday I had a very spirited ride about 50 miles long. Loads of corners, different road surfaces ranging from being great to rubbish.
I have a fully sprung seat and Thornton suspension fitted to my go faster Comet.
The gain in comfort is something that I never expected. As I was using the brake a lot to bed in the shoes I suddenly recognised how much the forks are moving now. Also going over ripples, the road holding and comfort are excellent.
Broken tarmac with 1 inch deep flat bottom potholes in series, no problem at any rate of speed. Same situation going round corners with a good lean at 40 to 70 miles, no fear, no wobbles, great road holding.
It is long ago I rode that kind of roads the same way on a standard Comet with standard dampers and I am sure tthe dampers also make a big difference, but this ride yesterday was great and it gave me full confidence in the bikes behaviour. To put it in simple words the bike feels more modern and safer now.
By the way I was pushing the bike through all these corners without any steering damper fitted, I had to make a new bracket to fit the damper but as the weather was great, I preferred to go out for a ride and give it some beans.

Bernd

 

[timetraveller]

I have recently received an order for six new steel steering heads. Then, on Saturday, I got another order for another steel one and then yesterday for one aluminium one. This is more than I have left of the steel ones and there are only three ali ones left after this one goes. My intention was to supply those with the ali head lugs which are under way. This means that there are non left for me. I do not mind getting another batch of ten made and having a few left on the shelf but do not want ten sitting there with a total cost of nearly £3,000. Is there anyone else out there who is likely to be wanting one? If so please let me know.

 

[erik]

I have fitted the mod. st. stem to my rapide .32 lbs springs and no inner spring.A new damper from the voc sp. comp. fitted. real sive ride with lots of comfort.Better roudholding than my standart comet.I would recommend it .Thinking about an Hydraulik steering damper.regards Erik

 

[timetraveller]

Nine hydraulic steering dampers are on order. Should be here next week.