New life for a 97 Mantra Pro?

[Kalamath]

I bought my mantra pro frameset new in 97 or 98...had about a year of riding on her when I moved to South Fla. in 99 and sat her in my garage till just this year when I moved to Georgia. I know theres more advanced designs these days, but she sure is a sweet ride even today. She still rides great and is superb shape. My only desire is to bring the actual suspension components into the modern age.

1. I know I can drop a new Fox RP23 in to replace the ALPS 5R thats on there, but I'm curious to hear if anyone has done so and what their experiences are.

2. Fork...the real conundrum. I really don't want to ditch the MC2 (I believe) because it's such a great system. Has anyone tried having a machine shop convert a newer fork by pressing a sleeve over the steer tube, or even replacing and fitting the original klein sized one to the new fork? I know some ppl will go "OMG you can't do that!" but it's totally feasable, and people race prototype gear all the time.

Please comment if you have any experience with these ideas, or just wanna chat about it. =)
You can check out my bike at http://www.sorba.org/forum/viewtopic.ph ... &start=165 posted by Kalamath.

[Tycho]

Kalamath, good to hear from you!

I've run a bunch of different rear shocks on the back of Mantras:
Alps 5R
Alps 5
Vanilla coil over
Vanilla air (R, RLC)
Stratos Helix Pro
Cane Creek AD10,12, Cloud 9

The Helix Pro, Vanilla Air (close to an RP23) and Cane Creek offerings have been my favorite. The Helix is great for running lots of sag with no bottoming and has a ton of tuning options (good for more downhill oriented riding). Vanilla Air is very smooth, not too heavy, sort of a good compromise shock, and the Cane Creek shocks are absolutely terrific for trail riding/racing (no big jumps) as they have a "platform" type feel to them when tuned properly and they're super lightweight ... they have a tendency to bottom harder than the oil damped shocks tho.

As far as forks go, I'd imagine you could have a sleeve made for a 1 1/8 steerer. I'm working on some solutions for MC1 and MC2 bikes that will allow new forks and stems but preserve the low profile integration of Mission Control. Stay Tuned.

-David

[Kalamath]

Nice to see activity still going on here Tycho. Thanks for the welcome, and the site! I'm definitely a more XC/race oriented setup, shock wise, since thats what I built the bike for originally. Honestly the current fork/shock are working great, and I've had comments about how good they feel for gear this old, esp. the fork. I have mountain spring "speed springs" in place of the stock elastomer/spring stack, and I run one medium and one stiff. Regular cleaning & maint. keeps this stuff running great.

As to your experience with these designs...have you run more travel up front? I sometimes feel that the front end could benefit from a slight lift. My Judy SLs are 63mm travel, and I wish I could experiment with 80mm and 100mm variants...

[Tycho]

Just realized you have a 97/98 frame which means a 6.75" rear shock. This means your only other option is the Cane Creek Cloud 9. No one else currently manufactures a 6.75" shock.

The Alps 5R is a terrific shock in my opinion tho. I remember first riding my friend's '97 Race back when I had a '96 Y11. I had a Mantra within a month of that ride. The Alps has a little higher seal friction than the newer air shocks, but is still widely adjustable, very linear for an air shock, and has good speed sensitivity characteristics on the compression stroke (shim stack compression damping, orifice rebound circuit). It's not nitrogen charged which means you can service it yourself, burp the oil chamber if necessary, change oil weights, and the lower internal pressures make it less prone to seal failure as well. I've had some spare negative pistons made recently (this is the oil/air separator) for a TMA reader who had his 5R fail and couldn't find a replacement shock in the correct length, so if you ever have the oil mixing with the air in a big way I can take care of that.

Mantras ride nice with a taller front end. On my '97 comp frame I ran a Psylo (120mm travel) for several years, then put a Fox Vanilla 125r on the front end of my '01 Carbon Mantra and now have a 2006 RS Revelation (130 mm travel). Making the front end taller mellows out the steering characteristics, which makes it a bit more difficult to pick your way through super gnarly uphill singletrack (something the Mantra excells at due to its quick handling and massive amount of rear travel and traction), but it makes the bike FAR more comfortable at high speeds down steeper hills (especially given how much the rear end can lift under braking due to the amount of sag that should be run in the rear). Going from a 3 to 5" fork slackens the headtube by probably 1.5 degrees or so.

On my Carbon Mantra, I run the seat all the way back on the rails and have a relatively short stem. I run about 1/3 total travel sag on the rear and run higher negative spring pressure than positive pressure on the fork (5" fork that sits down about 3/4" into its travel before I get on the bike). With the Helix I can run a lot of sag by lowering spring preload, but prevent bottoming by running high air chamber pressure. With this setup I have found the bike to be quite agile because I never have much weight on the front, and with the front fork so soft, it continues to track the ground very well (lots of traction, not much "weight" for the front tire to redirect when I do turn). Much of the steering is done simply by shifting my weight and "setting" the front end in the direction I want it to go. Wide tires (2.35s or wider) with gnarly side lugs let you lay the bike over in turns which also makes up for any loss of quickness due to head tube slackening. Oh, all that sag in the rear makes the bike incredibly stable too.

For an XC setup, a new 100 mm SID would probably be just about perfect.

[Kalamath]

Just realized you have a 97/98 frame which means a 6.75" rear shock.

This is a Mantra Pro....so it's a 7.875, and theres more variety as such. Like the RP23 =)

My Alps5R is doing ok so far...might be in need of a rebuild and fresh oil. I'm still messing with air pressure, trying to find whats right for me now that I'm older and heavier and riding rougher trails. The shock isn't rough....but at the same time it seems like it's not doing enough on small bump type hits. I'm VERY aware of how the URT design works so it's not a matter of me not keeping weight on the saddle. Maybe running a lighter weight shock oil would help.

As far as the fork goes, is the MC2 style steer tube 1 1/4" or slightly more than that? I don't have a micrometer nor a old 1 1/4" steerer laying around to compare, and I haven't found any dimension specs on the web. I'm guessing it's not that easy though...

After a few more days riding I can definitely say the fork would be the first thing to go...63mm is just not enough for my liking on my local trails. A nice new 100mm air shock would really bring this frame (even more) to life I think.

[Kalamath]

Another option I was considering is the mr wings long travel kit with aluminum damper....that'd bring me to 80mm up front. Only issue is, while the frame set is definitely 97 by every reference I have seen, the fork looks like it might be a 98 (one piece lowers, no big black stickers), and this kit says it's for 94-97.

Another thought I had was picking up a used 80mm travel judy and using the internals to convert my fork. For that matter, I wonder if SID lowers/internals would work on the Judy crown/upper.

These are all just bandaids though...a new 100mm still seems the best option if I can retain the MC2.

[Tycho]

Ah yes, of course it's a pro (with Mission Control). The lower part of the steerer is 1 1/2" and the upper is 1 1/4". The new headset kit shown on the front page will work for the lower bearing race on the '97 Mantra Pro, but I do not have a solution for the upper race yet (the upper bearing loads from the bottom of the headtube). The Reset Racing kit works well and is what I have on my mom's '97 Pro. I put an 80mm SID on there and it feels alright, but I think you should just go straight to something with 100+ mm of travel up front. All the old Judys and Sids are incredibly flexy forks in addition to being short travel.

I'll have to look into the stem/steerer interface on older MC stuff and see if I can't think of a way to make that work with the newer forks.

[Kalamath]

Ok I didnt realize the bottom was 1.5", thats awesome! I think finding a solution to work with the 1.5 taper forks will be the ticket. Probably Rock Shox since it looks like Fox only offers the taper steerer option on forks with 140mm and up, and that seems like it may be too much travel for this frame design. I don't want to lose too much of the quick steering.

My headset bearings are in fantastic shape, so it's just a matter of coming up with a reducer for the top spun up on a lathe. Or am I overlooking something?

edit: yep...I overlooked the MC2 issue....damn. If only they had a 1.5 to 1.25 taper...

[Kalamath]

Tore down the Judy since it wasnt feeling right....no oil in the damper (it has the al one, not plastic)....rebuilt it but after a few rides it's starting to feel like it's losing damping again. It's either salvage this judy with a mr_wings upgrade kit (gas charged sealed damper + springs @ 80mm travel) or just go for a new taper steerer fork and try having a machine shop press a 1.25 od sleeve on the top bit of steerer to accept the MC2 collet + bearing surface.

Anyone here tried out the mr_wings kit?

[Tycho]

Kalamath, there's one other possibility. I have a couple Manitou SX forks (one from my '99 Mantra Pro and another from my '01 Mantra Carbon). They are TPC forks that are still among the best 80mm travel forks I've ridden as far as damping quality/etc. I can send one of em to you if they'll work on your Mantra. They ought to as they are 1.5" lower 1.25" upper steerer diameter. You'll want to go through them to clean them up a bit and probably change the oil, but the dampers were working in top shape last time they were ridden, so you shouldn't have to mess with new seals or anything. Maybe put a Enduro seal kit on and ditch the boots?