To Brace or Not To Brace

padlock

padlock

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Location
bedford Uk
Any insight into wether it's worth using a fork brace or not. Don't really like the look of them but if there's a significant advantage I may use one. Had one on my LC back in the day and couldn't feel any difference. Cheers.
 
Padlock, the first question to be asked at this point is ;what specific handling problem am I trying to  resolve?
If you can't think of one then you don't need the solution!

A fork brace can sometimes introduce more problems than it solves [patter, stiction etc] so unless you really think you need one, I wouldn't bother. Properly fitted, they can reduce the tendency for the forks to 'walk' under heavy braking. In my experience this is something which is rarely encountered on the road but it all depends how hard the bike is ridden.
 
Tim,
Sounds bad, have you considered alternative forms of contraception?
 
Good braces have a form of adjustment to allow for out of true stanchions etc, ive had a Tarozzi one on the Monty for 25 years now with no problems at all, the trick is to assemble the brace section loosely, remove the springs & make sure the sliders travel there full stroke unhindered, then finally tighten everything up otherwise you will wreak the oil seals pretty quickly & will have stiction issues....
The 6mm holes in the bridge section are slightly slotted on one side to effect adjustment.
I have a mechanical anti dive on the LH side, so have to use a brace, the std 35mm Marzo's are pretty puny anyway, esp. on a Monty/F500 with there fibreglass mudguards....
 
ive had a Tarozzi one on the Monty for 25 years now with no problems at all,
Click to expand...

You probably haven't had much problem with fuel consumption either!  :D
 
Hi,

I had have a brace on my M1R and it gave me a real headache.
It came with the fork and also carried the front fender.
- strong stiction
- very uncomfortable riding
- leaking seals few days after having replaced them

All the measures to fix the problem have been taken but without success. >:(
Had to keep it because of the mudguard.

Finally I did cut the brace into 2 pieces, added a central plate, put them together and made the whole thing adjustable.

Et voila -> smooth damping, riding, no leaking anymore  :D

If you don't need a brace, leave it away.
 
Stefan3C said:
Hi,

I had have a brace on my M1R and it gave me a real headache.
It came with the fork and also carried the front fender.
- strong stiction
- very uncomfortable riding
- leaking seals few days after having replaced them

All the measures to fix the problem have been taken but without success. >:(
Had to keep it because of the mudguard.

Finally I did cut the brace into 2 pieces, added a central plate, put them together and made the whole thing adjustable.

Et voila -> smooth damping, riding, no leaking anymore  :D

If you don't need a brace, leave it away.
Click to expand...

couldn't you have just slotted the screw holes a tiny bit?
 
henry said:
...

couldn't you have just slotted the screw holes a tiny bit?
Click to expand...

Not possible, see the pic of the unmodified brace. The 4 holes in the middle are only for the screws to hold the mudguard.
Every time when I fitted the brace to the fork and tightened the screws it brought stress to the fork.

The modification has now an additional item with slotted screw holes to allow a stress-free adjustment.
UNMODIFIED BRACE:
M1__Fork_Brace_28unmodified29.jpg



 
I agree, a non adjustable fork brace might cause stiction and even an adjustable one is not neutral to installation faults. As Steve mentioned, you need to make sure the fork is "relaxed" and best is to loosen all screws except the ones from the top yoke, pull front brake lever, bump down the bike as much as you can 3-4 times, fasten the lower yoke screws, repeat the bumping process, fasten the brace screws, compress the fork again several times etc. and follow that process down to the axel nut and the according screws in the fork leg. This should be done btw. after EVERY wheel exchange, work on any of the components of the fork legs etc.

When my Jota returned from the complete overhaul, the dealer was not able to adjust the fork brace properly and the bike - once pushed down - didn't even come back up again! He suggested to bin the fork brace as "that is an unnecessary piece of crap". I took the bike home, followed the procedure above and recognized that he always obviously just had tried to adjust it via the central 2 screws. I loosened every screw on the fork brace, just slightly fastening them so that massive forces could still move parts a bit. I compressed the fork several times, fastened all screws only to compress the fork after each and every screw I fastened and - voila! The fork slights freely, no leaking oil seals since 12 years, stabile front end etc. - just great!

HTH
 
Stefan3C said:
henry said:
...

couldn't you have just slotted the screw holes a tiny bit?
Click to expand...

Not possible, see the pic of the unmodified brace. The 4 holes in the middle are only for the screws to hold the mudguard.
Every time when I fitted the brace to the fork and tightened the screws it brought stress to the fork.

The modification has now an additional item with slotted screw holes to allow a stress-free adjustment.
UNMODIFIED BRACE:
M1__Fork_Brace_28unmodified29.jpg
Click to expand...

well, that's a design i certainly wouldn't even consider - it's begging for trouble!!

just a thought, but which direction is the brace supposed to work in? is it intended to stop sideways flexing, or 'walking' - i guess more the latter. so is a brace like this the best design for that function?
 
Well - a fork brace should actually fix both fork lower legs so they can only move together, don't flex sidewards or in any other direction, at least not alone...

In theory - as long as this fork brace shown in the picture is not just a 2 mm plate but something like - say - 15 - 16mm at least, better 20mm, best 25mm at least on the sides - this should work fine in this regard. Is it optimal? No. Is it better than the original solution? Well - yes (if mounted correctly), as the original solution is - a 2mm alloy plate that is basically nothing else than a mudguard holder.

Especially on the M1R, you have two fork legs that one is for rebound and one for compression damping. to make them travel together and transmit the damping to both sides, I'd say a fork brace makes a lot of sense, at least theoretically. Flexing is not that big of a problem with the M1R, as the almost 42mm are a lot of material and the contacting surface between the fork and the stanchions is larger than with the 38mm or even the 35mm Ceriani and Marzochis. Also, there are already guides inside the lower legs that support the stanchions way better than with the 38 and 35mm forks. The fork is so stabile, that even the frame tends to brake after a while, so flexing seams not to be the issue you need to overcome with this fork.

I asked a specialist (HH-Racetech.de) if I would need a fork brace on this fork and he clearly said "Normally not". I asked him about the 35 and 38mm and he said "totally different story." The difference being a) the unsuported travel of the stanchions with less thick tubes and b) the guidance in the lower legs of these forks. When he mounts his cartridge system though, he bores out the lower legs, mounts some new guides that are longer and do support the stanchions better and then you would not need a fork brace normally, but could still use one if you like. But, the forces going into the frame are larger if the fork is stiffer. Best way to overcome this is a longer headstock and some bracing around the headstock and the lower frame tubes where they connect to the headstock. But who takes that hassle just for road-usage...
 
well - it does, as it improves the length of the supported area against the unsupported dramatically and hence the forces to bend and twist the fork must be way larger to achieve the same movement respectively the movement/twisting will be much reduced when the same forces apply. Pure physics, has to do with lever lengths etc. Easy to check: take a 1 cm thick and roughly 1 meter long plastic tube or wooden stick etc., try to bend it with your hands placed on both ends; should be fairly easy. Now move the hands in 20% from each side and try again. Way more forces have to be applied. Now make it extreme and move one hand to the center and try again...
 
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