LibertyFLS

Very nice! Looks great and was enjoyable reading your work. 👍

mountaindave 

I did Reading deeper into the site, that 720 was in for repairs, it wasn't built that year. It looks like '84 was the last year the 720 was produced. I saw one or two more instances where there appeared to be just one bike made in a particular size; I'd venture to guess those are more examples of warranty repairs or the like.

I've always shied away from the cantilevered 720's, preferring the regular side-pull 700's because of their greater adaptability to 650b if desired and their low-ish trail. But if a 25.5 720 came my way, I probably wouldn't kick it out of the garage for having a dirty drive train.

RiddleOfSteel

Thank you for the insight. I figured it was employees having one built for them (or building it themselves) outside of normal production orders.

As for non-canti 720s, looks like you're in for an '82 728. Beautiful bikes. I think my favorite 720 is a 1983, due primarily to cantis, and traditional lugs. The coloring is nice as well. The "TREK" teardrop seat stay cap remains my favorite detail of early Treks--it just looks so good, grown-up/mature/legitimate. Yeah, liking a bike because of that one detail can be a bit silly, but I like it. At any rate, I'd be happy finding a 1983 with rough paint so that I could add a few braze-ons (ST bottle cage bosses, DT shifter bosses) and re-paint or powder coat it. And like you said, I wouldn't kick an '82 728 out of the garage either...

mountaindave 

I do love USA Treks. An ‘82 720 would be a worthy addition to my collection. I could even ride a 24”.

This has been a fun thread, not your typical build recounting. I personally enjoy hearing people’s personal accounts about why they pick this or that - the customization of their special steed. Well done.

RiddleOfSteel

Sometimes you ride 40 miles with a friend and nothing happens except for a slipping seat post. Other times you ride by yourself and a ~30 year old drive side spoke gives up the ghost seven miles into a planned-28 mile ride, and your good friend @Dfrost comes and bails you out big time! I am extremely thankful/grateful!!!

So the 620 is down for the count, and I am planning on replacing all 32 rear wheel spokes. The fronts are new as of this summer, with the rear spokes soldiering on--albeit with my desire to replace them at some point. The butting of the rear spokes do not match the fronts, and though I be a strident "matchy-matchy" kind of guy, I somehow hadn't let it bother me. So what better time to rebuild/re-spoke the wheel (again!....) than with a bucket load of rain for the next week?

Taking stock of vintage pieces vs newer pieces, only the rear spokes concerned me to any degree. The frame, fork and headset are original and in great shape. The 7402 crankset is in great shape, as are the original MC70 canti brake arms/units. The 7400 hubs are in stellar shape along with the Mavic MA2 rims. New spokes should have the whole bike be fully 'good to go', so I should get to measuring.

Some photos of the temporary setback. :/

Stricken with grief! But still looking good in 39° weather...


One of these drive side spokes (I had mistakenly observed and reported it being of the non-drive-side variety) is disconnected from its hub-based counterpart. We had finally started to make time after slogging through downtown Seattle. Sigh...another time!

daka

You are a big dude to be riding a rear wheel with a measly 32 spokes. But of course you have been doing that for decades, right?

RiddleOfSteel

Eh, only 195 lbs over a 6'5" frame. 32-hole is fine, IMO. Heck, I've ridden multiple 1400g Shimano wheelsets with 16/20 F/R spoke counts and those were fine. I'm not hard on bikes or components, and employ mechanical sympathy as much as possible. Sometimes stuff just calls it quits. I hope to ride for many more decades, even if I'm working on completing my first decade of 'adult bike' ridership.

RiddleOfSteel

Oh the spokes again
Just can't wait to re-lace some spokes again
The life I love is rolling, shifting with bar-ends

And I can't wait to lace these old hubs again...

Lyrical appropriation aside, guess who's back doing The Most Fun Thing Ever (with regard to bikes)? Yes, me. Nothing like a forecast week of cold, wet stormy weather to set things right in Wheel Land.

I took some measurements of the spokes both as currently (well, now recently) installed and laced to tension, and individually once disassembled. This is to corroborate what I saw with my eyes: that these old spokes did not meet the bottom of the slot in the spoke nipple (aka too short by a bit). The laced spoke length (including the 12mm nipple) would be the "needed spoke length," and the individually-measured uninstalled spokes would be (naturally) the "actual spoke length." Let's see how close my "They're about 2mm too short" assessment panned out:

"Needed" Spoke Length:
Right/Drive Side: 299mm
Left/Non-Drive Side: 300-301mm

Actual Spoke Length:
Right/Drive Side: 296mm
Left/Non-Drive Side: 298mm

Good to know!

The broken drive side spoke snapped about 20mm up from the J-bend (head) near the hub. I checked the hub and it is in really nice shape, both visually (lovely shine) and with regard to spokes having dug into it over the years (at the J-bend)--quite minimal! 7400 Dura-Ace is magic, I tell you! The rim is in great shape, the aforementioned hubs are in great shape, and the nipples are new (brass) as of this summer and remain in great shape as well.

My normal spoke solution is DT Swiss Revolution (2.0-1.5-2.0) for the non-drive side, and DT Swiss Competition (2.0-1.8-2.0 mm) for the drive side. I have @Dfrost to thank for this. The present spokes are/were 2.0-1.7-2.0 mm, and the fronts, prior to my switching them out, were the same. I have a bunch of spare Revolutions, but only in the too-short 296mm size. Bummer! I think bumping up 2mm on spoke length would be a safe increase and satisfy the visual spoke-insertion-into-nipple part of the equation. Bumping up 3mm would give me a fully flush spoke (to the top of the nipple head) or just above that. I do have some wiggle room. IIRC, the reason for my having an extra set of 296mm spokes is due to the need for 298 or 299mm length on the TB14 wheel build I did for the Paramount several months ago (or several years ago in ROS's bike building timeline...). That spoke length ended up being good for the MA2 rim re-swap, and I think they have a touch of length they could go further.

Anyway, since the 620 is my sole bike, I'll be ordering the spokes pretty soon, thus enabling me to have a fully, fully, fully sorted bike now. Finally. Right?

And because pictures matter, here is the 7400 rear hub, completely free of spokes for the first time in pretty much forever. Don't mind the mild grime on the spoke nipples below it.

IsleRide

This has been a fun read documenting your careful and sympathetic build of a very special bicycle.

Regarding your touch up procedure. Did you re-spray whole sections of tubes masking at the lugs or did you "blow it in" and let it be visibly different?
This is tough to do even if you have perfectly matching paint but with 35 year old paint there is no way for a perfect match.

I'm considering this right now. Found a very close match but of the thinking it might be best to section it off and let the light reflecting off different planes and surfaces help blend it visually.

RiddleOfSteel

Thanks, man. As far as touch-up paint goes, I literally painted it on with the provided brush in a Dupli-Color all-in-one (I state this in previous posts) and clear-coated with the other side. No masking or anything. As you can see in some of the photos, the light shows the very slight difference. Five feet or more, and it's nearly impossible to see.

RiddleOfSteel

I should note, for the class, that a few drive side spokes had been mildly munched on by rogue chains here and there, so that makes spoke replacement even more of a good idea.

mountaindave 

And I’ll bet you can’t wait to get back on the road again!

Wildwood 

I had a large 80's 600 Series, with caliper brakes.
Your paint much richer, prettier.
Hope you enjoy yours, mine was not my cup-o-tea.
I understand @Lascauxcaveman likes them.

RiddleOfSteel

I've stated elsewhere that Trek color choices have always been hit and miss for me. The blue on that former 1985 600 (600 was also the model name, incidently--one year only) of yours is a nice enough blue, but I think a pearled or metallicized version of it would be even better. I like how the 600 is basically a 660/670 (racing models) of the same year, just with 1cm longer chain stays. I still look for those higher level racers because I really liked the high trail geo (same as this) of my 1988 560.

RiddleOfSteel

I should really just redo the whole song.

Wildwood 

It felt like the BB drop was too much. Maybe just the ride feel of that tubeset in such a large frame. I weighed in at almost 15 English stone.
edit: per catalog = bb drop 7.2cm, fork offset 45mm, wheelbase (size 25") 105cm.
Too much touring for my tastes.

RiddleOfSteel

I just double-checked to see if I had read the stats off incorrectly. I looks like you are pulling those numbers from the first graph/list/spec for the 400, 410, 420, 510, and 520. If we scoot two spec layouts down, we see the one for the 600. 73°/73.5 HT/ST, 58.5cm TT, 38mm of fork rake (trail is around 64mm), and a 72mm BB drop. Chain stays are still 42.5cm, but that's common on anything from the '70s. Wheelbase is a generous 104.3cm, though somehow a 1cm chain stay length reduction on an otherwise identical 660/670 yields a 3cm wheelbase reduction (101.3cm--right in line with race bikes of this size). What are numbers?!?

Dfrost 

I had the pleasure to check @RiddleOfSteel’s touch up work in person after the broken spoke rescue. It certainly passes the “five foot” test! I needed to get quite close to find the repaint and the match was excellent.
FWIW, I used that same shade of Dupli-Color (Chrysler “Deep Water Blue”) on a metallic deep blue Rodriguez for a friend and was also extremely pleased with the results.

wesley77803

How about a 1985 Trek 620? (Yes, it has cantilever brakes.) I have a 24" version that would let you duplicate this bike in a smaller size.

Maybe it is the 27" tires but the bike feels too big for me. The 24" 1985 620 feels bigger than the 24" 1985 500 possibly because of the longer chain stays.

I found a 22-1/2" 1984 720 on ebay so the 620 needs to find a new home.

RiddleOfSteel

There are frame/design elements that substantially contribute to the difference in feel between a 1985 620 and 1985 500.

The first significant difference is the chain stay length. 4.5cm (47cm down to 42.5cm). That is staggering!

The second significant difference is the wheel/tire size. The 620 employs 27" wheels with 27 x 1 1/4" tires, while the 500 is set up with 700C wheels and 700x25mm tires (and those tires measure a lot closer to 23mm by the time you're done with it). Doing some rough math, 700C to 27" = 8mm in BSD increase, or 4mm in rim radius increase. 1 1/4" tires = 32mm. Compare that to a 23-25mm diameter and you have a 7-9mm difference. The radius difference is now, more or less, 11-13mm. Nearly 0.5" is huge. You will also feel that height when you stand over the frame and also when you go to mount up on the saddle.

A byproduct of that wheel and tire difference is that the 500's 700C wheel and tire setup is considerably lighter, imbuing the 500 with a 'smaller' and more nimble feeling. Couple that with the increased tire height/diameter, which makes for a larger 'flywheel' effect in all situations, and the 620 will feel downright muted compared to the 500.

This is why I am and will forever remain a huge proponent of, if possible on a canti-brake equipped bike/tourer, to ditch the heavy 27" wheels and heavy, soggy 27 x 1 1/4" tires. You will make that bike come alive. As I've effused here in this thread, with my wheels (or anything close in 700C form) allow the frame to exhibit its full potential, performance-wise. Fast, comfortable, easy to spin up. Zero downsides. The tires are "33mm", though a touch small of that. The bump to 38mm Somas is definitely felt both in the slight weight increase, but mostly in the diameter increase. It's noticeable when out of the saddle (it rocks more slowly/less willingly), but in the saddle, the extra tire width is nice for cracked, crummy roads. I find that 35mm is about the transition point for larger tires for me. Under 35mm, they're more willing and energetic, over 35mm they're slower and even more comfortable.

mountaindave 

Thank you for the kind offer, but I will hold out for a 25.5” ‘82 720. According to Vintage Trek, some models still came with cantilever mounts, but as I’ve got a few Treks already, I can afford to wait.

RiddleOfSteel

@mountaindave you're looking at finding 1 out of 300 made for 1982 (the most 'prolific' year for 720 production)... Good luck.

I'll try and find 1 of 200 (for '84 and '85 combined). I'm gonna need a lot more luck...

mountaindave 

Yeah, I’m not holding my breath, but if one came up...

RiddleOfSteel

Yeah, neither am I. Doesn't stop me from looking though!

The Golden Boy 

I'm glad you're appreciating the 620! Out of all my bikes, I've put more miles on my 620 than any other bike. It is the bike that I generally choose for long recreational (unloaded) rides- it is THE reason I liken it to the ride of a 1972 Cadillac Eldorado. As I am fortunate to have both a 1985 620 and a 1985 720- I do think it's interesting that my take on the 620 has really changed in the past couple of years. I used to think the 620 was the heavier of the two. It makes sense that it would be- as 531CS is 531 and CrMo- it has to be thicker, and consequently heavier, to maintain the same strength of 531.. But the more I ride them, the more I'm convinced that the 620 feels lighter and rides lighter. I'm also surprised to read that you find the bike resistant to flex. I'm NOT a strong rider, but I've been able to ghost shift this bike when standing on it. My 720 is more resistant to flex than the 620. I think knowing that the bike is 531c* and reading dozens of people referring to the 720 as "flexy" really can color your opinion on things.

I think I got my 531 Treks in this order- 400, 730, 620, 720, TX700. When I got the 730, I realized how responsive and lively 531 really is. When I got my 620- it's naturally thicker and longer and heavier than the 730. I wanted a bike that had the combination of properties of the wheelbase of the 620 and the tubing of the 730- and I thought that bike was the 720. Realistically, the 620 falls between the 730 and 720 as far as liveliness and compliance- and it's a really nice sweet spot.

Regarding geometry- I find it interesting that the 85 620 is the same as the 660 racing frame- with different fork offset.

Regarding your 531 decal- there were 531CS decals- mine has one (I had to go back to the pix I took when I got the bike in 2011 to find a pic). I do think it's interesting that your decal is the same decal that's on my 86 400 Elance (which is essentially what a 600 series bike would have been prior to 1986).

620 531 by Dave The Golden Boy, on Flickr

400 531 by Dave The Golden Boy, on Flickr
(forgive this pic- I think I had a dopey camera and that's the best I could do back then)



Regarding the comparison of the 620 and 720- They're both excellently wonderful bikes. As you've noted, there were no 720s made in 1985 (except that one)-(I think the last one was built in Oct) but yet the tubing specs are different between 84 and 85- with 84 being "531ST" and the 85 being "531C." So I guess that would make every 85 720 made from 531ST- which is noted as being thicker, and consequently, heavier. I love both bikes- for the past few years, I seem to head for the 720 more- but I think it has more to do with it being set up with a 10 speed rear end than any weight/geometry/stiffness/compliance factor. It's just got more gears. Right now my 620 is in getting a lighting set up along with a fancy new 10 speed, 700c wheel set. I can't wait to get it back on the road.

85620Yard by Dave The Golden Boy, on Flickr

85720Yard by Dave The Golden Boy, on Flickr