1984 Trek 610 wheel conversion

[Keith Brown]

Hi all. 

Apologies up front if this question has already been answered. 

I picked up a Reynolds 531 built 1984 Trek 610 a week or so ago I plan to muck around with as an over-winter project. The frame is in great shape, save the paint job, but the rest of the bike is not. 

The bike is built for a 27'' wheel. I could easily swap those for 700c wheels and be done. But I think the best I can hope for is a 32mm tire and likely only about a 28mm with fenders. I ride 60/40 mix of road and gravel trail (multi-use paths) at around 100 miles-ish a week. I currently ride a 26'' Bridgestone XO-2 with Rat Trap Pass tires, which are nice and plump, so I'm accustomed to rolling over gravel like its nothing. It's been a long while since I've ridden a 700c bike and some time since I've ridden 28mm tires, but I don't think that's quite wide enough for gravel, or am I just spoiled? Is that really wide enough to provide enough kush? 

The alternative, naturally, is to 650b this bike, slap some 38mm or possibly 40mm tires and ride on. This is the far more expensive option, however. And if I have things measured correctly, I'm going to need 78mm of brake reach to mate those with 650b rims, which leaves me only the Dia-Compe 750s, which I actually know nothing about. 

Anyone ever futz with one of these frames? I'm open to any and all opinions/advice/hate mail. 

Thanks, all.

Keith.

[Michael Wong]

Hey Keith,

I rode. Motobecane 27->650b conversion got a while. I found 42 to be adequate, 48s bit better but heavy.

Brakes are the significant thing. It’s no problem getting the reach, but i couldn’t by the loss of power.

I feel that a brake bolt drop adapter is indispensable.

Michael

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[rcnute]

I've converted '83 Trek sport tourers with 38s and Dia-Compe 750 calipers.  Not sure if the Tektro sidepulls would reach as-is.  I actually prefer these 27" Treks as 700C conversions.

Ryan

[Eric Daume]

Suddenly the idea of drop bolts has me trying to squeeze 26” wheels into my old Trek 710, with a future drop bolt to make up for the reach. A quick check of what I have in my garage shows me that that 26x.1.95" (actually, about 48-50mm) just barely clears the fork, might barely be too wide in the chainstays if I could actually get the rear hub to fit, and would drop the bottom bracket about a 1/2" to 10.25". So 42mm would probably fit, dropping the bottom bracket to just over 10", but giving me a much better wheel selection than rim braked 650b. Hmmm.

Eric

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[Ken Freeman]

Keith,  I have that bike and have had it since new.  I don't really see a single or a few tech questions, but a few ideas being thrown out.  

1. Futzing - yes, I've done loads of futzing with the bike.  I hated the original brakes because the cables gave it a very squishy  feel, with poor brake response.  My other bike at the time was (still is ) a Masi Gran Criterium with original Campy Record sidepulls.  I felt the Campy were far better than the original Shimano 600/6205 in medium reach.  

2. But, the reach was perfect for 27 x 1 1/4, and it worked for 700c when I replaced the wheels with the Atom Maillard Helicomatic system.  Now I have Shimano 600 EX freewheel hubs, 700c CR18 rims with 32 mm true width.  They fit very well with SKS 45 mm plastic fenders, I think Longboards.  Takes some work to get the fenderline, but its worth it.  I could barely imagine using a 35 mm or 38 mm tire, but in the rear it might work without fenders.  

3. I replaced the original fork with a custom.  The offset of the original is 52 mm (trail around 50 mm), which I found to flop and wander as I went uphill on 700 x 28c.  I had it de-raked to about 43 mm (trail around 56 mm), which actually flopped worse but felt like a decent road bike.  But I wanted a front load, so I found a local shop owner to build me a new fork with 64 mm offset (38 mm trail), equal ride height, and a wider fork crown.  This could handle a motorcycle wheel, it seems, but gives a very nice ride and easy low-trail steering.  I did not go all the way to 650b.  The front fork has very long reach, but a left-over Mavic fits well.  The rear brake is still the Shimano 600/6207, and amazingly it clears the big tire and the medium-big fender.

I don't have much experience with gravel riding, so I am not an expert on what you "need."  I confess to not too much sympathy, since my gravel ride was 5 miles on a large fresh gravel, riding a really light Mondonico road bike on skinny 21 mm road tubulars.  The tires survived, the bike survived, and I survived. Can a smoother ride improve quality? I guess so.  But I have no idea how good it can get, nor any concept of what it means or feels like to have what I "need."  

28 mm wide enough?  Well I think yes, referring to my tubular ride.  But that's a very dark-horse option for gravel riding.

Ken Freeman, Ann Arbor, MI USA.

[Keith Brown]

Ken: 

Thanks for the thoughtful response. 

I guess I was just thinking aloud about the advantages/disadvantages of wheel size vs. what was possible with the frame. If I'm reading you right, you're able to fit 32mm tires and fenders in your 610? If so, that may solve my dilemma there. I could live with that. It certainly would be a sight cheaper. 

You must think pretty highly of that bike generally speaking to have kept it for this long, I'm guessing. That assures me that I made a wise choice picking up my own.

Thanks again,

Keith.

[Ken Freeman]

It is not as good a rider as my best 700c bikes (very lightweight Italian traditional steel) or my 650b (Terraferma 7/4/7 standard diameters), by a long shot.  Teh 32 mm tires are Challenge 32 mm Strada Bianca, which are the best 700c I've used but I don't just buy every tire out there. But if I'm going to do something crazy with a bike, technologically, it's a known quantity and I know how not to damage it.  Besides, it is not worth much $$ IMO.  I've also used it for some off-season medium-weather rides, like in November to commemorate the anniversary of the Christmas lights, or for Ride of Silence.  At the moment it has a Stronglight 46/30 chainset, vintage Huret front mech, Huret Duopar rear, and a 13-34 Sachs freewheel.  All shifts like butter, no indexing!

I have never felt it is very comfortable, even with Selle Anatomica saddles, but when I'm in shape and it fits well, I'm pretty comfortable for 20 miles. 

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Ken Freeman
Ann Arbor, MI USA

[David Dye]

I've got an 84 510 that I converted to 650b. It rides great and clears the Parimoto 42s easily. I used the Tektro 559, but added a bit of length to the slots. With Kool Stop salmon pads, it stops adequately, though not great. 

[Bob Chmara]

Keith,

I have an '82 Trek 613 that I've been riding for the past 10 years or so with 650B wheels.  I have Soma B-Lines on A23 rims and the chainstay clearance has never been a problem but it is minimal.  A 650x40B tire might be pushing it.  I also have it fitted with VO smooth fenders.  If memory serves, they're the 700c fenders and I had to work them a bit to get the fender line I wanted but there are no interference issues.  I haven't measured the BB height, but in practice, it's fine.  I'll sometimes scrape the top of my toe clips before I get them flipped around, but I've never had any issues with pedal strike.

The biggest challenge were the brakes.  The Tektro 559s are too short so I'm using Weinnman 750s and even then, I had to file the slots on the rear brake by maybe 2mm to get the pads where I wanted them.  Despite the reach, the braking performance is acceptable.  Nevertheless, if I can come up with a better setup, I would make the change.  I did try fabricating a Sheldon Brown drop bolt (https://sheldonbrown.com/home-drop.html), but I wasn't happy with the results.

Despite the somewhat less than optimal brake setup, it's still one of my favorite bikes to ride.

Bob Chmara
Southfield, Michigan

Keith Brown wrote on 6/22/21 10:21 AM:

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