Converting a 1985 Trek 600 to 650b

[Ryan Brown]

Greetings,

I aquired a vintage Trek 600 in great shape.  I am contemplating converting this vintage frame to 650b bike.  I have a couple of questions:

• Would this frame be a good candidate for a conversion?
• Should I use Nutted Tektro 559s?
• I am sure the drop outs are 126mm and not spread to modern standards.  Is that going to be an issue finding wheels for that hubsize?
• Does anyone have experience with this frame?

Thanks in advance,

Ryan in Madison, WI.

[Alex I]

Congrats on the bike find! I have an irrational admiration of old 80s Treks (never had one, just admire them and enjoy the styling for whatever reason).

For those interested, geometry info here: http://www.vintage-trek.com/images/trek/85TrekSport.pdf

What size frame do you ride Ryan? I'd be curious to check trail (http://yojimg.net/bike/web_tools/trailcalc.php). The frame has a really low fork rake according to the specs, pretty high trail it seems. Doesn't mean it wouldn't be a good conversion candidate, see the recent thread(s) here on low/medium/high trail bikes and preferences. 

Anyone have experience with a 7.2cm BB drop as a conversion with regards to pedal strike? Mine is a 7.0, and never had an issue with 650x38b tires riding SPD (M-520s).

Nutted brakes would be fine if that's what it's currently got. I recently put a "new" old fork on my frame that was set up for nutted brakes, so I've got one of each now (still recessed on the brake bridge). I picked my first set of R559s (and recent nutted front) off eBay for what I felt was a steal, but I would suggest grabbing some Kool-Stop Salmon pads to swap in, highly recommended for the R559s. The stock pads leave something to be desired.

You'll want to check brake reach, but according to the catalog it used short reach, so the Tektro R559s probably will work. Anyone know if there would be issues with the older Shimano N600 brake lever pull versus the R559s? Check this fantastic write-up for more info on estimating brake reach and tire clearances: https://www.bikeman.com/bikeman-blogs/650blog/1771-650b-conversion-guidlines

Plenty of 126mm hubs available in the wild, are you looking for an off the shelf wheel or would you build one (or have one built)? Do you want to keep the current component setup (was N600 6 speed?) or change to something more modern that would take 130mm hubs (such as 8/9+ speeds)? Cold setting a frame is straightforward enough (or spreading the dropouts) but do read up on it first, if you go that route.

Best of luck. Many much more experienced folks on here should be able to provide more thorough advice.

Alex, responding to questions with more questions in CO

[David Dye]

Trek 600 is probably not a great candidate, as the tire clearance is real tight. It can be done, but you may not fit much more than a 35. You'll want to measure the clearance before ordering parts. The widest part of a 650x38B tire is located 320mm from the axle center.

559's should work just fine. I actually like to get recessed nut brakes. Use the front on the rear and use a really long recessed nut on the front. It'd be nice if they sold a recessed front with nutted rear, but alas.

[Gabriel Hargrove]

I compiled a list of suitable 650b candidates from various threads on this and the I-BOB forum; so, I can’t take credit or vouch for the compatibility of each of these. Double check BB drop, but in regards to vintage TREKs I’d start with one of these:

1977: 500, 600, 700
1978: 510, 710
1979 - 1980: 710, 910
1981 610, 710
1982 412

I have a ‘77 TREK TX700 that fits 700x35s as is. So with chain stay dimpling I hope to get 650bx40. The fork clearance is the limiting factor. That year had the Cinelli type sloping Haden fork crown. Some of this year were built as 27” and some as 700c, I believe.

Other frames to consider (from another thread)
* Bridgestone RB-T; T-500; T-700
* Centurion Pro Tour; Elite GT
* Centurion Elite GT
* Fuji Touring Series
* Kuwahara Caravan
* Lotus Odyssey
* Mutate 610; 1000
* Nishiki Continental; Cresta GT; International; Riviera GT; Seral
* Panasonic PT-3500; PT-5000; Pro Touring; Touring Deluxe
* Raleigh Portage; Alyeska; Kodiak; Super Tourer; Touring 18
* Schwinn Paramount P15-9 Tourer; Passage; Voyageur
* Specialized Expedition; Sequoia
* Takara Overland
* Univega Gran Tourismo; Specialissima

[Brad]

The location of the tire moves toward  the rear with a a 650B.   My guess is that at 700 x35 with chainstays that get wider toward the rear it should be able handle 650B x 38, maybe 40 comfortably. 

The rim will move

(622-584)/2  farther back.

If my math is right that is 19 mm

I am trying to think of an everyday object that is 38 mm across since having one of those fancy dancy very nicely made tire size rods is not in my toolbox and probably not in yours.

You could just draw a 38 or 40 mm circle on a piece of scrap cardboard and move it forward and back by taping it to something like a chop stick.

The lid on Paul Newman Salad Dressing is about 41 mm in diameter.

[David Cummings]

Ditto on checking the bikeman link and checking for clearance before proceeding.  If it looks like you'll have room for the tire/fender combo you desire, go for it.  I've converted two Trek's to 650b (I'm about to do a third this summer) and two from 27" to 700c.  

[David Parsons]

How huge are the tires you want to wedge under it?   I 650b'ed my old Trek 1000 (similar clearances, I believe, but aluminum) and cannot fit anything larger than a confrerie under the rear triangle + fender.

-david parsons

[Don Vidger]

I was greatly helped by the Bikeman.

First issue is: What size wheel/tire do you have now? From looking at vintage-trek.com, early 1980's 600s could be 700c or 27 inch. 700c to 650b is quite doable; 27 in to 650b is going down 2 sizes!! the Tektro R559 probably won't reach.

Other issues are more tinkering (which I love to do). According to Bikeman it is 32cm from axle to widest part of 650b tire. You can "dimple" the rear chainstays to get more room. (I did a primitive version of this on my 1985 Trek 500 (fortunately it had 700C wheels/tires).

But first you got to get wheels. If you can build them, fine. If, like me, you have no interest in building rear wheels, I think the ones on the market have "freehubs" that take 8-11 speeds. "Freewheels"  only go up to 7 speeds and you won't find 650b rear wheels built that way (unless you build them). 

Borrow a 650b wheel from someone and see what tire fits. My trek 500 could handle 38s after dimpling. the 126mm rear space can just be forced open, or any shop can correctly expand to 130mm; or see Sheldon Brown's technique.

Your task is relatively easy, IF YOU HAVE 700C. Otherwise, too many problems.

On Wednesday, March 11, 2020 at 5:45:01 AM UTC-7, Ryan Brown wrote:

[Rashid Khan]

On Wednesday, March 11, 2020 at 8:25:10 PM UTC-7, Don Vidger wrote:

 

Your task is relatively easy, IF YOU HAVE 700C. Otherwise, too many problems.

It's definitely a case by case deal. My 1982 Trek 412 had 27" wheels, but was a really easy conversion with Dia Compe 750s. It took 650b x 42, with plenty of fender space, and was hoot to ride.

All else equal, converting 630 (aka 27 inch) to 650b is only another 4mm of break reach over converting 622 (aka 700c) to 650b. I wouldn't rule out 27" frames, they might even fit larger tires.

Rashid in PHX

 

PS ...

27 in to 650b is going down 2 sizes!!

700c to 650b is 4 sizes if we include 650, 650a and 700d! 😉

[Don Vidger]

RK: Cool! Thanks for the guidance and personal experience. Don

On Wednesday, March 11, 2020 at 5:45:01 AM UTC-7, Ryan Brown wrote:

[James Stewart]

Lots of Trek 650b conversions over on Bikeforums.com as well, in the classic & vintage sub forum.

Looks like the 600 was more of a race bike in 1985, the good 650b candidates are the 'sport-touring' models.

James

Montpelier, Vermont

[Mark in Beacon]

I believe a few of those Raleighs were actually native 650b. FWIW, my Paul Newman caps come in a little under sized, at 39.75. (That's the creamy Italian.)

On Wednesday, March 11, 2020 at 2:45:29 PM UTC-4, Gabriel Hargrove wrote:

[David Cummings]

It’s always best to check. I have converted two ‘81 56cm Trek 500’s from 27” to 700c - the first fit 38’s, the second barely fit 35’s (all panaracer Paselas).

I also have an ‘81 412 converted to 700c that has been hard to get 35’s and fenders, but it was likely one of a batch of outside-contracted frames that don’t fit the standard serialization pattern.

David “measure once, cut twice” in MT

[Ryan Brown]

Hey All,

The amount of responses has been so amazing.  I will post pics of the frame when I get time.  Right now I am trying to wrangle this COVID response at my place of employment:  It has been taking up all my time, to say the least.

The frame came with a headset installed and no other accouterments.  The brochure states that it used 700 wheels.  I have an extra set and might throw those on the frame and see how much I enjoy the ride.

I am not so sure this would be a great candidate for 650b.  The fork is less Low-Trail and less offset than I has originally thought.  

I am now on the lookout for a steel frame from that time-period to convert.  You guys gave me the bug. 

Thanks,

Ryan in Monona

[William Humphrey]

Ryan-I live in western WI and have a spare set of 650b wheels so if you ever want to experiment let me know and we can meet up.  The rear wheel has a 5 speed freewheel spaced to 126. Best, Bill 

[David Cummings]

We’re happy to help! You DID find the 650b group after all. It’s kind of like thanking the dealer on the corner for giving you a free sample of crack and then agreeing to sell you more! XP

David “thank you sir can I have another!” In MT

[Ryan Brown]

Hey all,

I took pics of the frame. I think the issue would be the Seat and Chain stays. Without measuring, they looks a bit tight for that expansion. I hope this link works.

https://imgur.com/a/uofo36G

Thanks,
Ryan

[Ryan Brown]

Better Pics: https://imgur.com/gallery/thFJ8U9

Thanks,

Ryan

[Alex I]

Awesome bike! Condition looks really nice. Is that some light shaping/dimpling on the chainstays? They do look pretty close together.

Did you have a chance to measure the stays at 320mm from the dropouts, per the Bikeman guidelines? On my 650b conversion, I took the dropout adjusters all the way out, and I slam the axle to the rear. My measurements worked out pretty well versus actual tire width, the calipers better than the ruler. And when I mounted CdlV's, they came out around 36mm actual width, so that stole a couple mm clearance.

If you check out the current Fuji thread, those are sweet conversion candidates, wish I had held out for one (but I have an unfortunate thing for LeMonds). My overhaul in progress is using an old Fuji fork circa 82, with about 57mm rake, stripped to chrome, to get lower trail. You could always go that route if you want to spend a lot of time for little return! But if the stays are limiting, not worth your time.

Best of luck. I do think if you're looking for low/mid trail, find another candidate. Trail is pretty darn high (entered data from the brochure for the 22.5" model as it appears to match your frame).

[Max]

Nice looking frame. Very worth a try. I’d converted a Koga-Miyata prologue, Trek 400, and Ibis Spanky. The Koga and Spanky accommodated 700x25 natively and 650x33. The Trek had clearance initially for 700x30, and accommodated 650x35 pretty well, with room for fenders. The limit was chainstays and fork — the former I could have indented, the latter not so much. Very nice ride, indeed.

Looking forward to photos of the finished bike!

- Max “idle hands” in A2

[Dan Sullivan]

Ryan, I think the 600 Trek is an underrated frame.  No knowledge of how it will handle a 650b conversion but it's definitely worth trying.  A very nice sport touring rig, and unless you think low-trail is magic you can't live without I think you have a good find there.  Dan S, just a little west of Monona (used to live there in mid 90s).

[Ryan Brown]

Thanks Dan. It really is screaming to be built up. I have enough parts lying around that I could cobble together a nice commuter and wait to see if a wheelset comes my way. I am in healthcare, I foresee me being pretty damn busy in the coming weeks/months. Be safe out there, folks.

[Michael Moote]

Sorry to bump this old post--- but how did the 650b conversion go? Looking at this frame myself and wondering how big a tire you were able to fit.