My ‘94 Mongoose Amplifier (AMP) and YouTube star

[Jimmy oldskool]

First of all I’d just like to make something clear…

I AM NOT SUPPOSED TO BE BUYING ANYMORE BIKES OR KIT UNTIL I HAVE FINISHED THE BUILDS I ALREADY HAVE UNDERWAY!…

…However…

This thing was posted up by Mark @MSYT a few days ago and really caught my eye.




Having been a fan of these for years and only having hard tails in my collection (other than the 29er epic) and the price being extremely reasonable, I thought I’d treat myself (despite agreeing with myself that I wouldn’t as per the above!)

So today it arrived and it’s awesome!!!



It needs a good polish, which my detailer at work is taking care of for me before fitting a new set of decals from Gil and it’s on to the build!




Build kit will be:

M900 XTR Mechs and Chainset
XT Thumbshifters
Avid arch rival brakes and levers
Black hope wheelset
Tyres TBC
Control Tech stem
Answer bars
CK headset
Seatpost TBC (although I would like a Control Tech to match the stem)
Obligatory Flite titanium
AMP rear brace (already fitted to the frame!)

All this is in the spares boxes so it should be a quick build…



I think this spec will be fairly light, very useable and look amazing once built up!

Just one thing I could use opinions on…

The frame came fitted with a 27.2 shim?



The post size is actually 31.6, which is readily available, so what are the benefits of any of running the shim?

I’ll keep this updated as I go

 

[MR OX]

Looking forward to this build!
Benefits to running the shim are fitting a Control Tech post that isn't made of unobtanium.
I searched hi & low of mine & was lucky enough to secure one from @Atmos who had the patients of a saint dealing with me!

 

[Suprachrgd82]

The post size is actually 31.6, which is readily available, so what are the benefits of any of running the shim?

A narrow seatpost is slightly more flexible and may yield a little more comfort. Probably negligible for [our] purposes. I suggest using the 31.8.

 

[Jimmy oldskool]

So a good getting at with the polisher by my detailer has left this looking awesome and the build is steadily progressing...



Avid arch rivals that were liberated from my Breezer Lightning have been cleaned up and fitted...I know they're a little later than the frame, but I struggle with canti performance and fitting aftermarket V brakes such as these save me from the guilt!



CK headset is installed and the thing of beauty that is the fork is on...This will probably be stripped again and painted gloss black and truth be told, should have probably been done prior to fitting it now...But I'm a child...I'm excited...So sue me!



KORE seatpost is in and the matching bars are fitted to the Control Tech stem. The KORE bars seem fairly heavy, so they may be swapped out for some lighter Taperlights that I have kicking about, although I am a sucker for finishing kit that matches. Those eagle eyed amongst you may have noticed that the stem decals are upside down...I love a racy nose down, arse up riding position and also the aesthetic that it gives when the bike is sat, so alongside the full set of new frame decals that I have coming, a set of new Control Tech stem decals will have everything the right way up again!



So that's where it is at the minute! I have everything I need to finish it, albeit in different states of cleanliness and readiness, so it should come together quickly from now on.

I'll update again as I go...

 

[Jimmy oldskool]

A bit more progress today…



M900 mechs and chainset, which is fitted with gold titanium chainring and extractor bolts bolted on alongside a gold KMC chain and XT thumbies to move it up and down the M737 block…





Then on went the hope wheelset shod with original 2.1 Smoke and Dart…



Really starting to love this thing now…Can’t wait to get the last bits finished off and the decals fitted…I think the saddle and grip choice will split opinion but think it’ll look awesome

 

[MSYT]

Damn. Really love how you’re transforming this!

 

[2manyoranges]

Lovely frame - I sold mine to a nice RtBer in Lewes a few years' ago.

I used an XLite seat post and I think this is important; the tube set is mighty flexible and it's good to get some rigidity into the system.

I rode the bike on the South Downs and learned a lot about its foibles.

I fitted XT V brakes and wondered why braking performance had not dramatically improved. Easy diagnosis. When you applied the brake, the pads touched the rim, and then almost all the power was lost to the chain stays bending outwards. So on went the after market AMP brace - which you have, and on went a brake brace - which you also have. Good call.
Good to have the brace on the front, too.

I noticed after fitting the XTs and brace that under heavy braking (which you do a lot on the downs on the Downs), the fork legs actual bent back about 15mm. Fine, but be aware that this will be a fatigue cycle in the fork legs. I have never heard of AMP forks breaking or cracking but I do think that it is something to keep an eye on.

I installed bolted axles front and rear, and that improved things too.

But the rear was always quite flexy, and it gave the impression of a flat tyre...or the rear end taking a different path to the front...which of course it was. That's something you just get used to.

Climbing was stunning, XC performance excellent. Downhill....a bit scary.

Oh...and a word on suspension setup. The concern back then was TRAVEL....get a much as possible. But Horst Leitner knew a thing or ten about suspension. You don't set up suspension without SAG. I had stock springs and contacted AMP in the 'States regarding spring rates. I am 5-7 and 135 pounds. AMP immediately send me some MUCH softer springs, which gave me about 20% static sag. That's crazy, people said, it's a small travel bike and now you have used up 20% of the travel. But suspension should allow the wheel to DROP into holes, tracking the ground. This transformed the bike into a smooth, grippy thing. I never recall bottoming out the suspension, despite some serious speed downhill. It's really important to set up the suspension with 10-20% sag, and then it works as it should...

this video is interesting since you can see the front damper working, but because of the suspension arc in the fork, it does not use much of the travel, even on quite big hits....this bike is significantly OVERSPRUNG and the rider will not be making use of the frame's potential....

 

[MattiThundrrr]

Horst Leitner knew a thing or ten about suspension. You don't set up suspension without SAG. I had stock springs and contacted AMP in the 'States regarding spring rates. I am 5-7 and 135 pounds. AMP immediately send me some MUCH softer springs, which gave me about 20% static sag. That's crazy, people said, it's a small travel bike and now you have used up 20% of the travel. But suspension should allow the wheel to DROP into holes, tracking the ground. This transformed the bike into a smooth, grippy thing. I never recall bottoming out the suspension, despite some serious speed downhill. It's really important to set up the suspension with 10-20% sag, and then it works as it should...

This is absolutely the truth. Sag is greatly overlooked by the majority when it comes to suspension tuning. Thanks for sharing your experience

 

[2manyoranges]

Nice history here.

Now THAT Was a Bike: 1993 AMP Research B2 - Pinkbike

Horst Leitner - the man behind the "Horst Link" - made the first production dual-suspension bike to bring the fight to the elite cross-country hardtail crowd.

www.pinkbike.com

The thing about Horst L is that he was A Very Throughful Man. The article misses something though. Springs are linear. So that means the AMP will barrel through its tiny amount of travel. Right? ....Wrong. Look at the links. They are NOT parallel. This means that the loading is not linear. The axle path meant that the leverage ratio could be tuned to take advantage of the spring...decrease the leverage ratio at the end of the stroke and you get progressive, air-like rising spring rate. Noice. And quite cheeky.

 

[Jimmy oldskool]

Lovely frame - I sold mine to a nice RtBer in Lewes a few years' ago.

I used an XLite seat post and I think this is important; the tube set is mighty flexible and it's good to get some rigidity into the system.

I rode the bike on the South Downs and learned a lot about its foibles.

I fitted XT V brakes and wondered why braking performance had not dramatically improved. Easy diagnosis. When you applied the brake, the pads touched the rim, and then almost all the power was lost to the chain stays bending outwards. So on went the after market AMP brace - which you have, and on went a brake brace - which you also have. Good call.
Good to have the brace on the front, too.

I noticed after fitting the XTs and brace that under heavy braking (which you do a lot on the downs on the Downs), the fork legs actual bent back about 15mm. Fine, but be aware that this will be a fatigue cycle in the fork legs. I have never heard of AMP forks breaking or cracking but I do think that it is something to keep an eye on.

I installed bolted axles front and rear, and that improved things too.

But the rear was always quite flexy, and it gave the impression of a flat tyre...or the rear end taking a different path to the front...which of course it was. That's something you just get used to.

Climbing was stunning, XC performance excellent. Downhill....a bit scary.

Oh...and a word on suspension setup. The concern back then was TRAVEL....get a much as possible. But Horst Leitner knew a thing or ten about suspension. You don't set up suspension without SAG. I had stock springs and contacted AMP in the 'States regarding spring rates. I am 5-7 and 135 pounds. AMP immediately send me some MUCH softer springs, which gave me about 20% static sag. That's crazy, people said, it's a small travel bike and now you have used up 20% of the travel. But suspension should allow the wheel to DROP into holes, tracking the ground. This transformed the bike into a smooth, grippy thing. I never recall bottoming out the suspension, despite some serious speed downhill. It's really important to set up the suspension with 10-20% sag, and then it works as it should...

this video is interesting since you can see the front damper working, but because of the suspension arc in the fork, it does not use much of the travel, even on quite big hits....this bike is significantly OVERSPRUNG and the rider will not be making use of the frame's potential....

Thanks matey…I had read about the flex in the stays on these hence the Avids and the AMP brace was a massive bonus!

Lots to think about regarding set up and I’ll have a play once she’s built…I may tap you up for some pointers…

The bike in the YouTube video is this actual one!!!