madpogue 

Photo assist:



What's the serial number? You should check it with the Asian Serial Number Guide - https://www.bikeforums.net/classic-v...ber-guide.html

texaspandj

The 1990 diamond back GT (EXPERT) was available in that same color way.
Dave Scott was riding a diamond back (but not a signature series) in 1990.
That's all I know but I I have a few speculations.

madpogue 

^^^^^ One of the '89 ads on the vintage-centurion site depicts a bike with crackly dark gray or black (it's a scan, so hard to say for sure) up front. But the year/model/color cross-reference page does not include it. No '89 catalog on the site, alas.

Still curious about the serial number.....

markwesti

Nice looking Turbo and a friendly price .
https://sandiego.craigslist.org/csd/bik/7558731173.html

seypat

Hot, and such good rides!

markwesti

I really like the seat stay wrap .

texaspandj

Agreed.
And Also Those Forks.

seypat

Just the right amount of chrome on both.

seypat

The departed Centurion OG is oogling and really digging this build from afar.

Cankles

After about 8 rides I’m really really loving it.

Fun fact #1. The 10 speed 11-36 contains all of the original tooth counts from the 13-24 6 speed.

11 + (13, 15, 17, 19, 21, 24) + 28, 32, 36

Fun fact #2 The original 52/42 13-24 practically had 7 unique gear ratios of 12 possible combinations. 1x10 obviously has 10 and 0 redundancy.

If you’re a chainline purist that hates 1x, just select your teeth counts to optimize spending time in the middle of the cassette. It doesn’t make sense in this scenario to argue for gaps since as shown the original freewheel was exactly as gappy. 10 speed 11-28 with less gaps still has as good of a climbing ratio as the original setup with a 48t front ring, while 48:11 is just more than I can chew.

Full respect for those who wish to maintain vintage drivetrain selections. My Ironman was naked when I got it so it was never gonna be left alone. I would not tear down a perfectly good bike to do this. Just sharing deets for fellow tinkerers with upgrades in mind.

seypat

That's a nice looking setup. Here's the issue I have with indexed 1X systems compared to my beloved triples. If you have to go say, from your 2nd or 3rd smallest cog up to your 2nd or largest cog and right back again, you do a whole lot more shifting than with a 2X or 3X system. I have to do that a lot. With the triple, I can usually shift the front once and a couple of back shifts or the front twice and 1 back shift and cover the same range. Over the course of an all day ride it becomes significant for me. with the long throw of a Shimano STI shift, my right forearm would eventually tighten up and I couldn't squeeze the brake lever. Microshift STIs with their 2 paddles have eliminated a lot of that problem.

Romany275

Sorry for the long absence since my first post - I had to fix a problem with my initial forum registration - all good now. The serial number for my 89 IM is 89D2966, which also seems a little different compared to most of the other serial numbers posted. Shimano Tricolor throughout - not sure if it came with the Biopace cranks originally and then changed later to what you see above. I actually just sourced some really nice white hoods that I'll change out someday. Wheels and hubs are Mavic Aksium but I have the Araya CTL-370s with Shimano hubs ready to go.

canklecat

Those are some sweet wheels. I love the old school low profile lightweight hard anodized rims like the Araya CTL-370 (370 grams per rim, reportedly, the lightest clincher rim of that, and possibly any, era), and Wolber Alpine Super Champions that weighed in the low 400+ gram range. They just look right to me on a classic steel road bike.

But they can be a bit fragile. I read those cautions online after getting my first set of CTL-370 wheels several years ago with my Centurion Ironman. Some owners urged caution in tensioning spokes to minimize the risk of cracking the rims.

But I didn't pay much attention to the warnings. Around 2019 or 2020, the rear rims cracked on both of my wheelsets -- CTL-370 with Suntour GPX hubs, and Alpine Super Champs with Shimano 600 hubs. The spokes began to pull through, with cracking around the spoke holes. I noticed the first set -- on the CTL-370 -- only because I heard an unusual noise while riding, but no difference in riding feel or stability. I checked the Alpine Super Champs and found the same problem on that rear wheel. Both front wheels were fine.

The rims might have cracked anyway after more than 30 years. But I neglected to measure spoke tension. These ultralight low profile rims tend to go out of true easily. Whenever I noticed a wobble I simply squeezed pairs of spokes between my thumb and fingers to roughly guesstimate tension as I used a spoke wrench to true the wheels by eye. After doing that for a few years I probably overtightened some and under-tightened others. That's especially tricky with rear wheels as spokes need careful tensioning on both sides. I did dribble lube between the spokes and nipples to be sure the spokes weren't twisting along with the nipples, but that probably wasn't good enough for multiple instances of truing the wheels over a few years and a lot of miles on rough roads.

If I get another set of those ultralight low profile rims, I'll get a spoke tensioning gauge and do the truing on a stand, rather than eyeballing it on the bike.

I've also heard recommendations to periodically de-tension and retension spokes on those wheels. No idea whether that suggestion is good, bad or "maybe, probably doesn't matter."

And riding supple tires, 700x23 or 700x25, probably won't hurt. They sure feel better. My favorites have been Continental GP Classics with root beer reddish-brown skinwalls (700x25 only) and Soma Supple Vitesse skinwalls. Excellent values, durable and long wearing with good puncture resistance without a harsh ride like Gatorskins or other puncture resistant tires, and they look great on a classic steel road bike. Continental Ultra Sports are also an excellent value, but a PITA to mount without a tire bead jack. When I rode Ultra Sport II tires I always carried a Kool Stop bead jack in my jersey pocket or strapped to my seat bag. The GP Classics and Soma can be mounted with just my hands, despite age and arthritis.

seypat

Araya still makes a hard anodized rim.

https://www.araya-usa.com/700crims/tx-733-700c

texaspandj

Oh yeah, the Ironman OEM wheels are so nice looking and performing.
My Centurion Comp TA was gifted to me as a frame (from you know who) has been one of my favorite rides. I used the araya ctl wheels off my '89 master and initially put some tractor tires on it as a gravel bike build. But they were too heavy and slow. So I had a new single 28 continental ultra sport that I got from a local shop clearance bin. I thought I might need for someone's repair. I decided to order a new matching one to replace on the Comp TA. I knew they would fit as the Comp TA has the most clearance of all my bikes. I only rode the Comp TA for months on short 10 mile rides on the river walk. I didn't notice any difference from my regular road bikes...until I finally rode my Ironman with 25s. I became convinced and a believer in 28s. And as C-Cat has mentioned plenty of times, those continental ultras are pretty dang good ride.
Bitd I rode 20s, tried 19s but went back to 20s. When I got back into cycling and later found this site I noticed the trend towards wider tires and thought I would never use 28s and eventually settled on 25s. Although all my Ironman have 25s (with the exception of my '89 which has continental gp 4000 23s) they will be replaced with 28s when the tread gets thin.
I've already checked and my 28 tires fit all my Ironman the '85 OG, '86 Classic, '87 Expert, '88 Carbon, and '89 Master.
Keep the rubber side down Ironkids.

Romany275

Getting some good feedback on the Araya CTLs. I have some rough roads here and there on my riding route. I've heard the Mavic Aksiums are pretty bombproof(?) so I think I'll stick with those right now - but nice to have the original CTLs in storage.

Romany275

Madpogue nicely posted some photos of my 89 Master on the previous page, but I'll post more when my post-count gets up there.

Classtime 

Did the CTLs come on an 85? Mine has the Bronze 20A rims which weigh between 416ish (weights from the www). Mine were re-tensioned by me as are all preowned wheels per the highly valued RT recommendaton and survived a many gravel rides in training for the EroicaCA long course. They are still true +/- 1mm which gets lost in 25mm rubber.

canklecat

Good to know. I might buy a set of Conti Ultra Sports in 700x28. They don't cost much and if nothing else they'll fit my 1990s Univega Via Carisma hybrid, which has handled tires up to 700x38, no problem.

Currently I have skinny road bike rims on that Univega to replace the 622x19 rims that were damaged when I was hit by a car a few years ago. I tried my favorite Conti Speed Rides (nominally 700x42 but measure closer to 38) on those skinny rims, but there wasn't enough shoulder support and the ride felt squirrely on fast sweeping curves and rippled pavement. Currently I'm using 700x32 Conti Sport Contact II, which are basically Continental's hybrid bike version of Gatorskin hardshells -- very rugged and puncture resistant, but a harsh ride.

I've been reluctant to buy any 28's in case they didn't fit any of my road bikes -- the '89 Ironman, '93 Trek 5900 purple people eater, and 2010 (approx) Diamondback Podium. All have very narrow clearance even with 25's.

The otherwise excellent Conti GP Classic skinwalls have a raised center rib that slightly rubs the rear brake bridge of the Suntour GPX group on my Ironman. I could carefully file down the bottom of the brake bridge -- a few swipes with a moto tool would do it without compromising structural integrity. But instead I ride a new set of GP Classics on another bike for maybe 100 mile until the center rib is slightly worn down, then swap 'em over to the Ironman. Or I could swap out the Suntour GPX brakes for a spare set of Shimano 600 or others I have in a box.

For folks who are doubters about the Continental Ultra Sport, I've used a wire bead Ultra Sport II in 700x25 on the rear wheel I used for the Cyclops trainer. I bought that one tire from Nashbar for maybe $5 when they were closing out their warehouse a few years ago after selling to another distributer. Snagged several bargains. I'd already been riding folding bead Ultra Sport II in 700x23 and 25 for a couple of years and found them to be an outstanding value in ride quality and durability. The only downside is the very tight fit and needing a bead jack to install them.

Conventional wisdom claims we need a special trainer tire for these indoor trainers -- rollers or mag type trainers with revolving steel drums -- otherwise standard tires will wear out too fast. But I've used the 700x25 Ultra Sport II wire bead tire on that Cyclops trainer for a few years, no problems. There's a bit of a flat spot in the tread, as you'd expect. Riding that tire outside for awhile would even it out. But I've never found any need for a special trainer tire.

Cankles

totally get it. I have a bike with 22sp 105 setup and even with a double/triple(?) paddle click it can be noticeable effort to traverse a cassette.

This amalgamation of non-overlapping technologies - friction downtube shifted 10 speed wide-ish range mtb cassette with a narrow wide ring - is a fun optimization of function/simplicity. I’m glad I have one such a rig to ride. It’s a fun n+1 setup. Might be my favorite but not sure it’d be my only.

But also, compare such a shift to the original setup. Big ring changes got you roughly equal to 1-1.5x the magnitude of a rear cog change, that’s it. When you look at the plot, it starts to look like there’s a whole shifter, derailleur, and second front ring just to do the job that adding a lil 11t cog woulda done.

When I first saw that 2x6 ≈ 7, I went for a 11-28 7sp freewheel (Amazon drift maniac). If paired with a single 44t ring, the 11-28 covers all the ground of the original setup 52/42 13-24 and then some. But I had mine with a 42 single speed ring so I was a bit short of the top 52/13 equivalent combo and not being NW it dropped a few chains.

motochick 

My husband took us to Colorado this year for a cycling vacation and while turning off the hwy to get to our airbnb, I spotted this '87 Ironman sitting outside at a pawn shop. It looked to be Adam's size but figured the guy would want an arm and a leg for it as it looked super clean even from across the street. We got it for a song and brought it home even though the seat tube is a tad bigger than what he normally rides. It was too good of a deal to leave it sitting outside in a small nowhere town. He modified it a bit to suit his tastes from parts we had in the parts bins and took it for it's maiden voyage this morning. I enjoy looking at the pretty colors while we ride.



Adam on his first ride of his new Ironman

2 Ironmans, one is flashy, one not so much

He has always wanted a radial laced front wheel, 32's keep it comfy.

texaspandj

Oh Yeah.
Both look really nice and that Miami Vice really pops.

Classtime 

Wait a minute! Those are 32mm Gravel Kings? 28s only gave me .8mm to spare under the rear brake on my 60cm Miami Vice.

motochick 

They are 32mm GK's, I guess your hammer isn't big enough! LOL. There is a ton of room on this frame in the rear, must be because it is a 62cm.

Brenda

texaspandj