mountaindave 

I would say that it’s not just tire selection, it’s also run selection. Those two things alone would be enough for me.

Add in your Helicomatic hub and there’s no question I would be trying a set of 700c rims to see if I could get them to work with the cantilever brakes. With only a 4mm difference in the radius, it’s very likely it will work. I’ve done it on an ‘85 Nashbar Touré MT (canti touring bike built for 27” rims from the same era).

With 700c you will likely be able to get a comfortably large and supple tire in a touring frame. I would be shocked if you couldn’t get a 38mm tire in there - even with fenders! Why limit yourself to only one tire on earth that is maxes out at 35mm in 27”?!

You also have so many options in the quality of the tires available. You can now buy clinchers that rival tubular tires in quality (for a price). But you can also find budget-minded tires with ease.

If you have a co-op around, or a LBS, see if they have any old stock they would be willing to get rid of. I’d venture to guess that a shop with 126mm OLD rear wheels would be happy to let them go for a reasonable price.

Good luck!

RRJohn

A testament to the wealth of knowledge on this forum, are the 25+ replies to my first question about a 30+ year old bike that is in unusable condition. Many thanks!!

jlaw

@RRJohn,

If they appear to be properly functioning currently you can run the Helicomatic hub and Duo Par derailleur until you get something better.

The Kool Stop road pads are definitely nicer than the MTB pads and I would get a set to replace the existing original pads asap because the bike will stop better.

Have fun and post pictures.

RRJohn

OK, who has a Helicomatic wrench to sell or loan? I will be starting on the 620 rehab this week and will need the wrench to open the hub. Ebay has a couple but maybe there is one in someone’s toolbox looking for a new home.
Thanks,
Robert

The Golden Boy 

You can just use a needle nose pliers- just be careful not to crush the ring.

RRJohn

Thanks. I will give it a ‘gentle’ try. Also, I’ll check with the LBS to see if they might have a wrench I can borrow.

The Golden Boy 

You might actually be able to take it off with your fingers- depending on how tight it was tightened on- I was surprised by how easy mine came off.

RRJohn

I just tried that but no luck. This one hasn’t seen any lube in 25 years.

Hobbiano 

I have removed that retaining ring with a good pair of channel locks with sharp jaw serations. Just carefully squeeze only hard enough to grip the splines and get it to start turning. I'd squirt some penetrating oil on it first and let it soak a while. It's not supposed to be very tight. I would be supprised if the cones are still in decent condition, though. How does the axle feel when you turn it with your fingers?

RRJohn

It feels dry but not rough. My friend at the LBS dug around in a drawer and found the needed wrench to remove the lock nut. It was tight enough we had to bump the wrench with a mallet to start the nut. I will check the bearings and cones tonight.

Hobbiano 

Did you get to check out the condition of the cones and cups of the rear hub yet? Just wondering. I have an '84 620 waiting for me to give it some attention. The hubs (Helicomatics) feel rough but the braking surfaces on the rims, as well as the rest of the bike, show low use. Maybe the bearing surfaces or still good - not counting on it though.

mpetry912 

You can run the Helicomatic if you like - it's an elegant design but parts - especially wear parts like cones and sprockets - are hard or impossible to get and like the jubilee derailleur, prone to catastrophic failure. I like to ride bikes that are absolutely reliable - and not worry about something failing far from home. Long term you should probably consider a new rear hub or complete wheel. There are lots of options out there but in freewheel hubs the Phils are best IMHO.

Mark Petry
Bainbridge Island, WA USA

cannonride15

@mpetry912, curious what catastrophic failures of Helicomatic hubs have you experienced (or heard of)?

mpetry912 

they are notorious for stripping the splines off the freehub, and the cones aren't great. It's a neat idea but in my opinion poorly executed.

Mark Petry
Bainbridge Island, WA USA

The Golden Boy 

From a current user here:

Well, others may have different experiences with them. Pain # 1 : they only accept Helicomatic freewheels, which you can only get on ebay. Pain # 2: They don't last very long, and when they crap out you need a special tool to remove them. I could probably handle Pain # 1 and 2, but here is my experience:

Last year I was hammering up a steep hill in a fairly high gear when suddenly and without warning my Helicomatic freewheel said "Non!" and decided to freewheel forward instead. My pedal zipped around at an astonishing speed and cut right through my ankle, all the way to the bone. I looked down at my leg and in addition to all the grease and gore I could see a little dangling achilles tendon, like a fishing line, and the chipped bone. It took half an hour for the doctor in emergency using what looked like a pot-scrubber to clean all the grease out of the wound, and during that half hour I came up with all kinds of names for the Helicomatic system that I can't reprint here. So yeah, they freakin' suck, that's the problem with them. Just my opinion, of course.


Whats wrong with the Helicomatic hub?


Then there's the Sheldon page:

Both hub flanges were 1mm farther to the left than those of a normal hub, causing increased dish in the rear wheel, and persistent spoke breakage problems. Many loyal Helicomatic fans tout the ease with which the cassette may be removed for spoke replacement as a great virtue, but if the hub were better designed, it wouldn't break so many spokes!

These hubs were prone to bearing problems as well. Due to clearance requirements, they couldn't fit the normal 9 1/4" bearing balls, so they used 13 5/32" balls on the right side. These didn't hold up well. The cones tended to wear rapidly, and replacement cones are no longer available to fit these hubs.

https://www.sheldonbrown.com/velos.html


And from the man who installed more Helicomatic hubs than anyone else here:

The problem with the Helicomatic hub was that the design required smaller bearings (5/32" vs the typical 1/4" in rear hubs) and these did not hold up as well as the larger balls. More frequent maintenance can obviate that problem. Service your hubs before the big ride. Replace the balls with new ones and ride in confidence if nothing untoward was seen during the pre-ride service.

While the pitted races on one of my Helicomatics can be blamed on being a lower level unit (from a Trek 420)- it seems that even the upper level hubs suffer from the same problem. Maillard was capable of making great, great stuff- but the tradeoffs that were made to design the Helicomatic were not good.

Life is too short to play **** **** games with junk you know is junk.

Some stuff gets a bad reputation because people don't know how to use it-

Some stuff is just plain outright bad- I shake my head when people are looking for or buy first generation Mountech rear derailleurs...

mpetry912 

think of it like a Citroen with two wheels. Neat idea, clever design, but too complicated and prone to fail with parts that are hard to find.

Mark Petry
Bainbridge Island, WA USA

tcpasley

+1 on the Kool Stop Cross Pads. They are pretty short, so you won't have problems with them hitting the fork legs when you are removing the wheel, especially since the pads on your original brakes mount in front of the brake arms. Also, the pads are narrow, so they will work if you want to run some vintage tubular wheels with narrow brake tracks.

Here is the best deal I've found:
https://www.ebay.com/itm/KOOLSTOP-CR...kAAOSwAClcYizE

After the initial purchase of pads and and holders, replacement pads are pretty common and cheap.

I'm building an '84 620 frameset using a hodgepodge of parts I've accumulated, along with a few purchased for the project. I'm starting with some 700C wheels with Campy record hubs (126mm OLD rear) and Mavic MA40 rims, but I also have a couple sets of Campy Record-hubbed tubular wheels. I imagine a Trek 620 running wide tubulars would give an absolutely luxurious ride.

pastorbobnlnh 

Just to clarify: The Helico Matic hub does not use a "freehub." Instead it has helical splines to carry the Helico Matic specific freewheel (as opposed to threads for traditional freewheels and visible in the photo below).

And I'm shocked to see in The Golden Boy's post quoting the late Sheldon Brown who referred to a Helico Matic as a "cassette." It truly is a freewheel.

Hobbiano 

I'm guessing the op saw something disturbing when he took the hub apart.

pastorbobnlnh 

I'd like to offer an apology to @mpetry912. I meant no ill-will and will revise my post in order to remove any implication of criticism.

Feldman

Three comments/ideas based on having owned one of these bikes and built/fixed dozens: Borrow some 700c wheels and see if the brakes work--just an adjustment check. Your 620 was made when 27" wheels were going out; my. own fit 700c's which could have been by design but also could have been just manufacturing tolerances giving me just the right brake post placement. You will find buying 700c tires much easier and, as good as that range of Treks is to ride, you'll wear out some tires!
Many fine rim brake wheel sets are selling cheap these days, just check craigslist. One of my regular customers has bought a few, the quote from him "They're so twentieth-century that nobody wants 'em." He scored a nice Ultegra6500/Open Pro set for $100 earlier this year.
Helicomatics--fast wearing cogs with tooth profiles that guarantee some bad shifts, parts only available at collectors' prices--what's to like?
Wheels that can use Shim/SRAM/Sunrace cassettes will make your life much easier.

mpetry912 

@PastorBob no need to apologize ! You're right, it's not a freehub, but it's not a freewheel either ! kind of a halfway in between. Sorry about our semantic disagreement over design nomenclature.

Seems to be near universal agreement that the Helicomatic (how did that part get machined anyway?) is not the most robust design for a bike that you plan to ride a lot. Neither is the Cinelli Bivalent for that matter, and I have a set of those on a bike hanging in my living room. Kinda like the Helicomatic, the Bivalent will strip out the freewheel splines, and it's expensive to repair because you pretty much have to buy another one to get parts. Bordering on impossible because they all failed.

Anyway an interesting discussion. And yes, very satisfactory rim brake wheels can be found - or built - that are good enough to last for the remainder of your riding career. Personally I like Phil hubs and Shimano MF 7400 freewheels.

Mark Petry
Bainbridge Island, WA USA

RRJohn

I’ve been off grid a few days so late in getting back to this. Disassembled the hub and found that the cones are scored( as predicted by many). Man, those are some small bearings!! The original rims need some work and spikes, so I will check the 700c fit and start looking for a set of affordable wheels that will handle a light touring load. Suggestions are welcomed.

jlaw

DT Swiss 460 rims, Ultegra hubs, 130mm rear spacing which you should be able to fit into your frame

Fits 7 speed (cassette with 4.5mm spacer), 8,9,10, and 11 speed cassettes. You may need a new RD - but could still use friction shifting for 7/8/9 - 10/11 may be a challenge using friction.

Machined braking surface.

4.4 lbs for the set.

18mm internal width - good for tires up to at least 40 mm

$229

Seeing these I might buy a pair for my 620!

DT Swiss R460 Rims Road Bike Wheelset 8-11 speed 32h Ultegra [741463] - $229.00 Velomine.com : Worldwide Bicycle Shop, fixed gear track bike wheelsets campagnolo super record vintage bike

jlaw

Those wheels are likely built by machine so you or your LBS should check for true and round.