Jmpierce

I think this is the correct place to post this.

Vintage MTB. Mongoose. Never came across one like this before.

A friend is tuning this up for a friend.







At first I was thinking aluminum Mongoose, couldn't be anything special right? Then I saw the Campy rims, and the Shimano Dieore derailleurs and thought, wait what the...

Anyone familiar with this MTB? From what I can find its pretty rare to find one that hasn't had frame separation issues.

merziac

I'm getting a kink in my neck just trying to visualize the pivots trying to actuate, especially under load, at speed on any rough going.

Roger M

The fork has been replaced. It should have an Amp Research fork.

I have an Amplifier that I bought new in 1994. It was a cool bike, and now mostly a good conversation piece. I've never had problems with the pivots, but I think parts are still available for rebuilding them?

Cool bike you have.

Jmpierce

Yeah we're trying to convince the owner to not ride this very aggressively and possible just hang this on a wall.

The ore I get into this the more interesting it gets.

merziac

Well a shiny correct fork version is a little more understandable and cooler looking but it still looks to me like the rear is a very convoluted version of the front that still isn't going to work well long term.

dddd

That style of "Horst Link" rear suspension pivot location (below and in front of the rear axle) was awarded a patent that Specialized (among others) happily paid royalties on for many years.
Horst Leitner was the inventor and creator of the AMP bikes, Mongoose's version was a little different at the down tube iir.

The benefit is that braking loads have minimal effect on the suspension's movement, preventing "brake jack"-induced wheel hop and loss of directional control.

The mounting of the rear shock in line with and taking lateral loading from the chainstays makes this a "strut" type of suspension, and the shock must be designed for such loading, usually by using a thicker shaft. This reduces the number of required pivots, simplifying and lightening the rear suspension, though it isn't the best setup for longer-travel applications.

This bike will probably hold up fine for relatively mild riding with a less-than-heavy rider. A lot of bikes see worst-case usage and these were prone to failure under such usage just like many other 1990's mtbs were.

Darth Lefty 

It’s pretty plain compared to most modern bikes that now also have a shock linkage to tune the leverage and a lot of styling. Are you just complaining about suspension bikes in general? This stuff serves a good purpose, it mitigates brake jack and improves the axle path. Lately with 1x systems they’ve been able to really dial it in, the chain tension vector was all over the place with 3x

The rear hinge of the Horst link ahead and below the axle is really distinctive, you can still see it on Specialized, YT, Guerilla Gravity. Not clear to me why this won out opposed to a brake arm like on a motorcycle but it works.

dddd

I'd guess that the design initially won out over a caliper carrier mounted on the axle because of the existing bicycle rear hub and QR architecture being completely different than a motorcycle's thru-axle.
And since then, other, lighter designs still manage to carry the braking loads without adding any moving parts.
Note that some downhill bikes have used brake torque arms with proprietary hubs and axles, since the added weight wasn't much of an issue on those rigs.

Trek went as far as designing concentric chainstay (swingarm) and seatstay ends that pivoted about the rear axle in order to isolate braking forces from the suspension's movement, and it's just one of many designs to do so. But prior to virtual pivots, the Horst Link's simplicity was extremely attractive (recalling that my GT LTS featured the Horst Link pivot as well).

winstonb 

You wanna talk crazy suspension design! https://www.ebay.com/itm/11452928778...sAAOSwD1BfsvUH

T-Mar

+1, that's basically a rebranded Amp Research B2 frame. Mongoose struck a deal in the early 1990's with Horst Leitner of Amp Research company. Here's the test from the December 1993 issue of Mountain Bike Action magazine.

merziac

Not complaining in general, although I have no use for them, never was my thing. Collecting a few old ones though.

Really just spitballin and showing my ignorance, I did ride plenty of dirt MX's back in the day then switched to street bikes and drag racing for my deal.

Seen plenty of new fangled, latest, greatest suspension setups, wheelie bar mods, cocka mamie deals on atv's, snowmobiles, drag bikes, street bikes, cars, trucks and a lot else so just applying my experience for me here.

zukahn1 

Surprisingly a lot of the suspension design elements on these are a through back to the 70's Huffy mono shock BMX bikes which were the first mass produced mid frame suspension bikes.

clubman 

AMP gear felt exotic, like Citroens.

That Moots is so far from what I want in a bike.

degan

Looks like Mongoose had a bunch of extra straight, sloping crown, threaded steerer forks and wanted to make a new bike so they killed two birds with one stone and used a fork as the seatstays and just put the other end of the shock wherever on the frame it happened to land with that fork.

T-Mar

That's Leitner's original design, pre-dating the deal with Mongoose. The Mongoose models were basically Taiwanese built clones of Leitner's Amp Research models.

FBOATSB

Very interesting tech to look at although I have no experience with any bike with suspension. If after the tune up the owner wants to pound it into oblivion that's his right to do so, I would never know. But I would more lean towards finding an original fork if possible and continuing to preserve that sort of thing just so I might see a pic of it occasionally

degan

Okay, but my point remains the same. It looks like a fork in there.