Bought an old 1997 Proflex 757 - need suggestions on upgrades to original parts

[agriff404]

I suppose a little cramped, but I like it for the most part. I have ridden my friend's large frame bikes and didn't really find them any more comfortable, but not sure I have ever tried a medium frame.

So you would say have the shocks serviced, rather than replaced? I found this site: https://j6shocks.com/Mountain_Bike_Services.html

Is that the best or only place to get them serviced?

[Spokes]

Servicing them will probably be your easiest and cheapest option over buying new replacements or making something else fit. Thats the problem with Proflexs, especialy the '56 and '57 range, as the rear suspension is specific to them. Vectors and crosslinks are the same with not much else on the market that fits them.
Noleen are not the only place but they are obviously the original suppliers. Over here in UK we take them to a motorcycle/car suspension service Center and they do the service as sending to Noleen in USA takes too long. Have a look what's local to you.

Chris

[fyrstormer]

I'm 5'7" and I weigh 175-180, and I ride a Medium frame with a 350lb/in coil spring on the rear shock. I also have a Noleen NR-4 rear shock which has compression- and rebound-damping adjustments, whereas your bike has a Noleen NR-1, which has no adjustments. I suspect the reason it rides poorly is because the bike is too small for you, and the spring rate is probably wrong as well. Not being able to adjust the damping characteristics can't be helping any.

Taking apart all the pivots, cleaning and relubing them, and tightening the bushings just enough so the swingarm slowly droops under its own weight, should help a bit, but ultimately the suspension geometry is what it is. If you're used to less-expensive bikes (Pro-Flexes originally sold for $1500-2500 when new), you might be expecting the suspension to be very "plush", which is a marketing buzzword that means "too damn soft because you bought suspension and you want to feel it working all the time". Whereas, Pro-Flexes were essentially designed to be "soft-tails", which means they were designed to round-off the edges a bit when you hit a bump, nothing more.

Technically the suspension travel is in the 3" range, but it in the real world it doesn't perform the same as 3" suspension on a newer bike. Because Pro-Flex used a single-pivot suspension design, the shock has to be tuned pretty stiff to avoid bobbing while pedaling. Also, because the spring rate from a coil spring isn't progressive like it is with a compressed-air shock, the spring has to be stiffer than a comparable compressed-air spring to avoid bottoming-out over relatively small bumps. (there *are* progressive-rate coil springs available, but they make pedal-bob worse at any given spring rate, because most of the stiffness is at the end of the shock travel.)

The good news is that your 757 has a forward-mounted main pivot, unlike my 756 which has a rear-mounted pivot, so the pedal-bob effect is less of a factor for you than it is for me. It's still a factor, though.

Servicing the shock will certainly help a bit, because I doubt it's ever been serviced before; replacing it with an NR-4 or a Risse shock would help even more because you can tune it to suit your preference; but ultimately your best defense against getting a headache is to lift your butt off the saddle when riding over rough ground.

[agriff404]

Thanks, Fyr.

Well bad news - I took it for the tune-up and he called me and told me that the frame is cracked and to start looking for a new bike as he doesn't recommend riding this one anymore. He wasn't there when I picked it up, but the only cracks I was able to find was on the rear Pro Active yellow part, which I wouldn't consider the frame, but maybe that is what it is considered as I am not sure what to call it otherwise. I tried searching to see if that part was replaceable but couldn't find anything. Is it considered a rear fork? Is that part replaceable or is the bike junk now? As far as I could tell, the blue frame was still fine.

The two cracks were on the smaller poles on the yellow aluminum piece that runs up to the rear shock

[w2zero]

Most likely the two cracks on the rear strut (that connects the swing arm to the shock) are where the bonding joint is.   Further inspection by someone familiar with bonded parts would be in order. 

The crack in the swing arm could be solved by finding another swing arm on ebay, craigslist or on these forums.

[Spokes]

Post a picture of the 'so called crack'. It sounds to me like its just cracks in the paint on the rear strut. Nothing to worry about. Like I said, these bikes are retro and most people don't know what they are looking at as far as Proflex is concerned. Don't throw it away just yet , let us see it first!!

Chris

[agriff404]

Yea, that is what I was thinking as well - couldn't really tell if they were cracks in the aluminum or just the paint. The cracks are perfectly circular which I thought was weird. But the guy at bike shop loves to talk about how he's been doing this for lots of years whenever I doubt anything he says.

I don't have bike on me right now to get a pic as it is at parents, but will get one as soon as I can. May try scraping some of the paint away as well at the cracks and see if that reveals anything.

[w2zero]

Share the pictures before you scrape the paint off.   Would be a shame to have to paint and didn't need to.

[Spokes]

Have a read of the thread "Cracked rear struts" , posted by Rossco a week or two ago. It sounds like you've got exactly the same situation as him. Like we said then, the rear struts are bonded together so a crack in the paint is nothing to worry about. There are photos to compare yours to as well.
Welcome to the wacky world of Proflex ownership where most local bike shops will tell you they are too old and no good for anything. Don't believe them!!!

Chris

[agriff404]

Yes, the crack is exactly like the one shown on the referenced thread:

I talked to the guy that did the tune-up and he said those were the 2 cracks he was referring to. He doesn't recommend riding it still. Is he just covering himself or is the bike safe to ride?

Anything I can do to ensure it is safe to ride?

[w2zero]

Those are seams where the adhesive bonds the strut legs to the crown, they are not cracks.   His concern may be in part a desire to sell you a new bike.  Grasp the strut crown and torque it by hand.  I doubt there will be any movement. 

[Spokes]

Honestly your strut is fine! He is probably just covering himself for lawsuit reasons!

Chris

[agriff404]

Thanks guys - glad to hear I don't have to ride my old bike with zero suspension and look to save for a new bike. Not going to bother doing a tune-up with that shop anymore I don't think. They have not impressed me in a few areas. I will just buy a few parts from them to use up the gift cert. I have with them and just do tune up best I can myself probably. I got most of the gears working last year, but I think the problem is the rear derailleur gears are pretty worn imo, as well as the front crankset has some pretty good chipped teeth. They cut all my cables before noticing crack, so need to buy new wires as well. I am sure with Youtube and Google, I can figure most things out and learn something along the way.

If anyone has suggestions on the rear derailleur to get or the crankset, I appreciate input on those.