AMP frame and fork helped needed

[howman66]

Dear All,

I would like some advice on my AMP Frame (B-2, Mongoose with twin down tubes) and AMP F-3 with carbon legs.

I would also like to offer that I am running Bullseye hubs, a King Aheadset (with a "headlock" - that is, a bolt compresses a top and bottom camp so there is no star nut), a Thomson stem, LP carbon fiber bars and seat post, and a Risse Astro-5 rear shock. The rear shock is set up for about 190lbs, as, that is probably what I weigh with my backpack, water, tools, et al. I am a slower, clumsy rider, 48 years-old, riding on rock and sand out here in Cairo, Egypt. There is an area called Wadi Degla, and it is just a tremendous amount of fun, with some great folk out here to ride with.

So, with that, I need some advice please.

Problem - I have a bit of wobble when testing my headset. I have tried everything. Rebuilt the forks, installed the "headlock," checked the bearings of the hub (which are maybe a hair loose-goosy, a hair). I believe I have installed the stem correctly each time (headlock first, then clincher/side bolts). When I feel the King bearings, they feel just fine. (I would like to also mention that I have had the bike since 2003 or 4, built from new parts (minus the fork) and have put less than eight long rides of more than two hours.

If I hold the front brake, I get a forward movement of about 1/8 inch, maybe? Both brakes, nothing. Sitting on the bike with the front brake, nothing. Stem turned 90 degrees, nothing.

I am starting to wonder if this "play" comes from the rear suspension perhaps, and I feel it up front? I feel, and see no real movement in the parallelogram or legs. Does anyone have any thoughts or advice? I will soon travel to the US, and, I am trying to make a spare parts list, wondering if I should try a Crane Creek treadless headset perhaps...

Advice - Do I need to worry about the carbon fiber legs on this fork? Again, the area is very, very rocky. It is very hard on people and bikes alike. I ate rock and sand twice on the last outing. The other guys have much newer bikes and ride away easily, but, I think that is a motor problem, not a bike problem. Also, I prefer my toe clips, and I have to get out of them a lot, so, I am not ready, now at least, to make another stab at clip-less.

But, I suppose, what I would like to know is if the carbon legs are going to hold up to my weight and the terrain (I do not go very fast except for the rolling hill parts, and my wipe outs were a the top of a hill, and on the side of a hill, not too fast...). I do not want to break the fork, but, I guess that perhaps they are rare and I should hang them on a wall or sell them. Honestly though, I have so much fun riding the bike, that, I would rather do that...just ride it...but, worried if the forks are made in Italy - fragile...

Thanks a lot in advance for reading, and any thoughts or advice you may have. I am grateful.

Best wishes,

Howard

 

[focomat 1c]

Re:

I have AMP F1 and AMP F4 forks on a couple of bikes ( Univega and Cannondale )

I have experienced the same 'movement' when holding the brakes on, and believe this to be a combination of the suspension
geometry and the slightest amount of wear in the 8 pivot bearings being magnified by the suspension design

I am not sure that the environment you ride in is best suited to your suspension type ! A few years ago I stopped riding my F1 forks
on rocky trails. I found that the amount of twisting force applied to the handlebars, and down to the tyre contact point, through
the 8 pivot bearings was too large in my opinion. Even at rest, twisting the bars while holding the wheel steady produced slight flex.
Add to this a fine abrasive like sand !!! working its way into the bearings and you have a recipe for wear and tear, and frequent servicing

Neither of my forks have carbon fibre legs. However if they did I would like to know something of their history. This includes other CF
components as well. It is possible that in the past the legs have suffered impact damage nearly to the point of failure, however we
can never know this. All you can do is minutely inspect the legs at the likely points of failure, where they are inserted into the alloy
sleeves top and bottom. It is possible that a more probable cause of concern will be the integrity of the bond between the sleeves
and the legs themselves. This bond has been a problem on many 'glued' bike frames in the past

It may be comforting for you to know that it is extremely unlikely that both legs could fail at the same time ! ( unless you ride into a wall ! )
so there is no reason to stop riding your bike, however there used to be a neoprene cover available, that fitted over the complete front
suspension system, excluding dirt, dust, mud and sand from getting in to the pivots/bearings. I would try and obtain one of these

 

[howman66]

Thanks D.D. for the reply. I am grateful.

I think you are right, that the movement is a combination of all play in the pivots. I was having another look just now, again, and it is the fork that is moving forward, almost expanding a bit, if you will.

I will try to construct some kind of cover, or, swap forks all together. I love riding the bike, but, maybe I should save it for fire roads in another country...

D.D., thanks again.

 

[ishaw]

Re:

You probably have either some air in the fork damper, play in the bushings, or both. Servicing the damper is quite simple, changing the bushings and pivots also quite simple, though you do need to take a hammer and drift to get the old parts out, and the new parts in.

I've got a full set of replacement pivots, bushings and a dampers service kit if you wanted to take the forks?

I used to have the same bike and did this myself as well as servicing the rear shock. I've got a spare risse air shock for the bike too if you wanted one?

 

[howman66]

Hi Gold Trader,

Thank you too for your reply.

To the best of my ability (for whatever that is worth) I have rebuilt the dampener many times, and rebuilt the fork, and the movement is still there. Perhaps the fork had a rough life before I bought it, not sure. I will have another look through it all and see. I will travel to the US soon, and I need to come up with a plan...

1) Get another AMP fork as a back up;
2) Get another cantilever fork;
3) I just keep riding it, just a year to go, and save my pennies for a new/used bike next year.

If I can find someone here with an old, cantilever front fork, I may try to swap it out to make sure it is not the headset...and it could be as that is the only thing that has not been replaced, but, it was/is a new King Aheadset. I think D.D. might be right, just too many moving parts that add up to a big movement...

Thanks for your offer for the spares. A Risse rear shock I have, which is awesome, and I have spares for the original shock. The bike is such a joy to ride though...and I hate the idea of changing it, though, that sounds better than a face full of carbon, and in traction... I will take inventory of what I have and shoot you a PM.

Thanks again