AMP Research research

[dyna-ti]

My recently-acquired B5 frame would love your F4 fork, if you ever decide to sell.

I saw your post earlier and knew i was risking it letting on But sorry, this ones never for sale. Moree chance of your frame coming to me than vice versa. If i could afford it and postage that is :shock:


I got it not long after joining RB and looking like this.


One spring missing completely,plus the collars naturally. EVERY pivot on the dampers spidered with minute cracking :facepalm: and of course both dampers leaking.
On the plus side the cracks ended on the pivots and were not anywhere important llike the dropouts.

Found an engineer willing to do the work as a lunchtime project(actually when i arrived at the engineers there was a Kona in the workshop that belonged to one of them so i knew then i had a good chance of the work being done.
The owner hadnt ever seen Amp Research stuff and was blown away and jumped at the chance to work on it, and i guess during he would look with interest at how it works from a cyclists view and that of a professional engineer.
That chap made some job of all the pivots(just replaced the lot) new oil bearing bushings, the works.
He also made a jig that when used with a bench vice makes for preloading the spring to adjust it and moving the collars and keeper wires a real easy job. So easy i laugh at the threads asking how to do it

I had the springs wound at another wee engineering works with about 4 staff, they charged me £20 to make two springs identical to the single i got with it.

Then i sold it and then i regretted ever selling it and started a begging thread for the chap who bought it that i really wanted it back eventually after about 3 years finally managed It wont be leaving me again So sorry.

Made a good job of it But apparently one of the dampers is weeping slightly. An old 0 ring i think :?

Sorry for teasing you with it

 

[r32]

You've got a better story than I, so that's okay. Especially once bringing a knackered fork back to life, then the "once was lost, then found" bit.

In my case, I just spent some money on the 'Bay and ended up with the frame, some M952 XTR bits, and a complete Mercedes-Benz B4 donor bike. There is a £300 fork that is correct for this frame available, but significantly nudges the spend. I would do it for the right candidate though. In any case, this is quite the rabbit hole, if you wanted to be accurate and on a budget.

I stripped this frame down to its pivots, its a beautifully made, CNC-machined thing, but the bushings are tiny, and I didn't realize how much friction there was. The shock was blown, so I will have to budget for a Risse. I'd originally wanted to just use the F3 fork, but realized then it was not going to match the rear travel well with only 2.25 inches of travel.

Oh well, at least I have the bespoke brakes and hubs, and whatever else I'd need to strip from the frame......which is not a lot really. But those are the hard-to-get bits - rather get them in a set that mess about with fiddly little fittings that never come up for sale because no one thinks they're worth putting up on eBay and ends up sat in the bottom of their toolboxes and yes, this bike has many of those things.

 

[AmpresearchB3]

Thanks Swede for sharing the MBA articles. it's been almost 20 years since I read them. Been a fan ever since

 

[dyna-ti]

Oh well, at least I have the bespoke brakes and hubs, and whatever else I'd need to strip from the frame......which is not a lot really. But those are the hard-to-get bits - rather get them in a set that mess about with fiddly little fittings that never come up for sale because no one thinks they're worth putting up on eBay and ends up sat in the bottom of their toolboxes and yes, this bike has many of those things.

Good idea on the brakes/hubs. Those are exceptionally hard to find even across the pond. Is the front mount the 2 small holes on the protrusion on the left dropout or is it on an adaptor which takes it to about 38 or 40mm(ive not measured it in a while)
Someone on here has made some other adaptors that go directly onto the dropout mount, which gives you modern post mount. admittedly theyre a bit chunky and industrial looking but it serves a very useful purpose. Theres a thread on it somewhere :? .I added one to mine for the extra option. Cant go wrong and it wasnt expensive really..

My only chance for getting one is for a hopeful part exchange with someone on here. Otherwise its a bit of a pipe dream really.

You guys are literally falling over them and its just a matter of how much you spend to get the finest example to work with.

Grass is always bloody greener

 

[r32]

Well, yeah, it is my intention to first go with the factory build-out then see how badly the brakes and hubs work (my point of reference is a really sweet set of Shimano XT 4 pot brakes). At least the rear hub is a 8-speed Shimano XT with a bolted-on disc adapter so replacements should be plentiful. I'm also iffy whether the 95x series XTR brake levers give the correct pull for the AMP calipers.

My front brake caliper bolts to a small step-up plate but remains a bespoke spacing. I plan to buy those adaptor plates, front and rear, in the event I need to go on to more modern brakes on IS mounts. It also means I can use 6 bolt ISO mount hubs as well, rather than the oddball three-bolt jobs now. But that's part of the charm of a retro-build, I suppose - making something I lusted after in my youth, come to life of the magazine spreads so I could finally ride it and see what its like.

We don't "literally fall over" B5s here. Not by a very long shot, because I had been looking for a fair bit. I saw maybe 2 or 3 in the past year on eBay, or Craigslist on the East Coast, and I didn't follow up on them because of cost, or being too incomplete, or being generally in a bad shape. B3 and B4 are a bit more common though, and you can find occasional spurts of Mercedes-Benz/AMP MTB and police bikes appear.

 

[r32]

I'm currently at a crossroads - do I go eight speed XTR or nine speed XTR? The cranks and rear derailleur I have prepared for the build are Mega 9 but are backward compatible to 8 speed. But now I will need to decide to purchase shifters and cogsets to match. I notice that the full length cable housing that B4/B5 bikes use introduce more friction than traditional bikes with cable stops. Will the added friction mean that the coarser cable pull for 8 speed works better than 9 speed for shift precision?

 

[Swede]

I'm currently at a crossroads - do I go eight speed XTR or nine speed XTR? The cranks and rear derailleur I have prepared for the build are Mega 9 but are backward compatible to 8 speed. But now I will need to decide to purchase shifters and cogsets to match. I notice that the full length cable housing that B4/B5 bikes use introduce more friction than traditional bikes with cable stops. Will the added friction mean that the coarser cable pull for 8 speed works better than 9 speed for shift precision?

Can't help you with that but have you read trail_head's thread. It's well worth it as his bike isn't too different to yours.

 

[r32]

Re:

Yeah I read his thread but am going a somewhat different direction. He does run a 3x8 drivetrain though so that might be a hint.

 

[B3]

Re:

Another nice bike is Hazer's build

viewtopic.php?t=139296

 

[r32]

Does anyone have much experience with the AMP rear disc rotor mount flange that bolts up to Shimano rear hubs? I'm thinking of upgrading the rear hub to 95x XTR, but I'm not sure if the hub flanges are identical.