jlaw

A BF member has a Trek 760 frame and fork for sale. I like 650b, but with 415mm chain stays and mid-80's race geometry, do you think 650b x 38 with fenders would work for this frame and fork?

Full spec. and geometry for this bike can be found here:

https://www.vintage-trek.com/images/t...TrekRacing.pdf


I figured I'd ask others who might know before requesting that the seller take measurements.

bikemig 

You may have seen this but this link is pretty good in terms of the measurements you should be thinking about when doing a conversion.

https://www.bikeman.com/bikeman-blog...sion-guidlines

natterberry 

I doubt this would fit. I question whether I could fit 700x28 in mine.

caloso

This.

If I were going to do any kind of "conversion" to a 760 frameset, it would be to build it up with a modern road group and wheels. That was a heckuva race bike in its day and it could still be today.

bikemig 

Hey its the OP's bike and this is no big deal. Someone else can turn it back into a racing bike. I am skeptical that this is a good 650b candidate though.

Bandera

What a hideous thought.


-Bandera

jlaw

Come on! I've got a 'race' bike already and it bores me.

650b with fenders, floaty tires, 10 speed Gevenalle shifters, etc.on a race frame - now that sounds like fun!

shoota 

I seriously doubt you'll get 38s in there.

gugie 

In answer to your question, no. There are other vintage Trek models that would work.

Unless you remove the fork blades and stays, braze new ones in, then sure!

USAZorro

Had one. Could fit 28's in, but I don't know what you'd do for brakes.

The Golden Boy 

"Mutilating" is hyperbolically overstating it.

"Neutering" or "emasculating" might be more appropriate.

I try to "tour" up my bikes- and I've gotten as far as putting a rack and triple on my 78 730. I don't think even I would do that to a 760. That bike is special- and this would, IMO, be disrespectful to that frame.

jlaw

A simple answer from a voice with experience. Thank you.

Since I've got your ear.... I converted a 1985 Trek 410 to 650b x 38 with fenders, Daija Far Bars, etc. - great bike with a True Temper frame that fits me very well and I can hammer on that bike (or what passes for me hammering!) . I also have a 1984 Trek 620 that I cleaned-up over the winter and have ridden a few times - Reynolds 531CS with a more relaxed geometry - seems a little too mellow and since it has canti brakes I'm stuck with 27" or 700c wheels.

So, I'm looking for a Trek frame and fork with 126mm rear spacing that uses butted 531 steel and is suitable for 650b. I now understand that a race geometry will not work. So.... the 400 Elance uses 531 steel...? Any suggestions?

Thanks!

The Golden Boy 

FWIW- putting 700c x 35 Compass tires was the best thing I ever did for my 85 Trek 720.

FWIW- the geometry of the 85 620 was identical to the 85 660 race bike- with the exception of the chain stay length and fork rake. I don't know about the 84 model.

If you're that on the idea of cushy tires- I'd do 700C and Compass Bon Jon Pass tires on the 620.



FWIW- my 86 400 Elance has the most aggressive geometry of all of my bikes- with the exception of the chain stay length at 42.5.

I've toyed with the idea of doing 650B on my 400 Elance. While I don't have the tires I really want on it- I do have the brakes I really want on it.

bear_a_bug 

I'm less critical of your thoughts on converting the bike to 650B. However, I think I would be aesthetically critical of any attempt to "fender-ize" it given the lack of eyelets. Seen some ugly hacks out there.

I like where you're headed, though - a quick handling race bike converted to comfy tires. Best of luck.

rando_couche

WTF? A Trek 760 is not all that special. And a 650b conversion is not a downgrade by any means, when done well.

rando_couche

Amen. My favorite 650b conversion to date is an 80's vintage Mondia Super. This is NOT the same thing as a Mondia Special. Very aggressive, racy geometry (I measured the head angle at 75 deg on a 64cm frame), and with the indented 531 chainstays it (just barely) has room for 650x42b's. It's a match made in heaven. Smooth, fast enough for me, and those tires give it rock solid handling, regardless of the surface.

lostarchitect 

650B = un-manly now?

Personally I think racy bikes are the best for 650B conversions. You get aggressive geometry with a cush ride--what's not to like? And it's not like this bike is super special.

rideandgoseek 

This all has my chuckling because that is in fact MY bike. Well, my old bike, I sold it a year or so back. Those are 25mm Continental Grand Prix Classics and man they barely fit. This bike also had ridiculous toe overlap. I don't know much about 650 conversion but I'm guessing no.

Happy to see this picture though. I remember it was the same day as Eroica in Gaiole so I went out looking for some gravel

The Golden Boy 

I would disagree about the 760 not being super special.

There's a point to where you take an item that had a single, badass purpose- and gentrify it into a non-threatening, leisure machine... I'm not into racing bikes- most everything I have is cushy and leisure- and I didn't understand why people took offense to my ideas of taking mid-late 80s competitive MTBs and turning them into leisure cruisers. I get it now.

bikemig 

Running different size wheels is not mutilating the bike. This mod isn't likely to work on this frame given the tight tolerances but the frame itself will not be touched. You don't like the way fat tires look on racing bikes. I get it but that's the OP's choice, right? Personally I like old European racing bikes because, by and large, they can take a 28c tire and some can take a 32c tire.

gugie 

As you're seeing, tire size and geometry are two different "knobs" to affect your ride. Tubing brand and make are essentially inconsequential - as long as the wall diameter and thicknesses are the same. The vintage bikes you're looking at all use "standard" diameter tubing sets (not oversized). A True Temper tubeset will ride about the same as a 531 for the same wall thicknesses. The only difference might be the butted lengths, but now we're talking "princess and the pea" difference in ride.

What you're looking for are "long legs" - long chainstays will give you more width where the tire's widest point is, longer fork blades (crown to axle dimension) gives you more vertical room - fork ID is rarely an issue. BITD, these were sold as sport touring or touring bikes.

A 400 Elance would be an excelent bike for a 650b conversion.

gugie 

Ah, the alternative definition of Gugificazione...

repechage

There are ideas, and there are questionable ideas.

I think it is time to go frame shopping.

Andy_K 

I've got a 1982 Trek 614 that I think would be a pretty good 650B candidate.



Only the main triangle is 531, and the rear brake needs a little more reach than you get with a Tektro R559. MAFAC RAIDs might do it. Otherwise, it's fender-ready and has good tire clearance. If you're dead set on ful 531, I think the 715 from this period had that with the same geometry.

natterberry 

Im in process of this now actually. I have (pretty much) all of the parts, just have to put them together.