tarsi 

I have a 1985 Trek 720 which according to vintage-trek.com came with a 5 speed freewheel. The bike came to me with 6 speeds. Two of the cogs have a fair amount of play between the spacers and adjacent cogs but I'm still waiting for removal tool to see exactly what is going on.

My question is, are there any options to get to a 7 speed setup and if so, what would it involve? The goal is indexed brifter shifting. I've read about using 8 of 9 and 9 of 10 cogs to fit on 7 speed hubs and would be open to any unconventional solutions such as these.

friday1970

Ditch the entire helicomatic hub.
I stuck with 1985 Peugeot's helicomatic hubs from the time I bought the bike new in the 1980's. But after 3 rides in one month of spokes just popping and ruining my rides (riding 13 miles back to the car with the tire rubbing was the last straw), I ditched the wheelset for something more modern. This allowed me to use modern brifters and the ability to easily find tools to swap out cassettes.
The problem with helicomatic hubs were spoke breaking. Sheldon Brown's site also mentions this:

"The Helicomatic was a nice idea on paper, but poorly executed. These hubs are losers. 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!"

I went to modern wheelsets on my two Peugoets and haven't looked back.

Kontact 

You need to replace the rear hub or rear wheel. Replacing just the hub basically means throwing out everything but the rim and building a wheel with new spokes and hub.


You can go to a 126mm wide 7 speed hub, or cold set the frame to 130 and install a hub that can take anywhere from 7 to 11 speeds. I would be inclined to go to the wider format and a quality 8/9/10 wheel. I like 8 speeds for the low component costs.

friday1970

Tarsi, I went this route as well. RJ the Bike Guy on Youtube has a very easy-to-understand tutorial on how to do this. You will need a ruler or some digital measuring calipers for this

And in order to go from 27" to 700cc tires, I bought a pair of Tetro 559 brakes, I also had to use an 8mm drill bit and a right angle drill attachment to allow the recessed nut of the tektro brakes to fit properly.

Links to what I bought:
https://www.amazon.com/TEKTRO-Reach-...+67mm+calipers
https://www.harborfreight.com/38-in-...ent-69337.html
https://www.harborfreight.com/6-in-d...ngs-62569.html

The bolts I used to coldset were 5/16th x 12in threaded rod, with 5nuts and washers. Didn't cost much, about 3 dollars for all of it at Home Depot.

Link to RJ's tutorial:

Kontact 

You don't need digital calipers to make the spacing about 130mm. You don't need precision to any decimal places. A ruler works great.

The actual bending can be done with bare hands, a board and padding, etc. When the OP decides to go that route there are many resources.

The hardest part is really aligning the dropouts after spreading.

Chombi1 

Agree, you get it within a couple of mms to what spacing you need (better being on the wider side so wheels slip in easily) and you should be fine. Not everyone does a realignment of their dropout faces zfter cold setting the stays with no real consequences, but if you can, do it.
I now remember the severe dishing that Helicomatic hubs did have after reading this post. Thankfully, I did not break any spokes or flanges at the rear wheel, but I went through two sets of hub bearings when they ground themselves up into smithereenees after not too many miles..... The undersized bearings are another good reason to ditch Helicomatic hubs.

The Golden Boy 

You don't need to do any of that cold setting or anything- the bike is spaced at 128- it has 47cm long chainstays- it's really easy to just slip a 130 spaced wheel in there.

I have a 1985 Trek 720 that came to me with the stock Helicomatic and I replaced the rear wheel with a 130 spaced Phil Wood 10 speed wheel.


IMG_1714 by Dave The Golden Boy, on Flickr

If I understand your question correctly- you want to use the Helicomatic "freehub" as a freehub for a regular cassette... That's not going to work. Not only will normal cogs not fit on there, but even though a Helicomatic is a "cassette" it's still more like a freewheel.

Your best course of action is to get a different wheel (or wheel set) either with a freewheel hub spaced for 7 speed if you wish, or a cassette hub for anything spaced at 130.

The 720 is a "lifetime bike," it's a unique and fantastic bike. Nothing you put on there will outclass the bike.

I'm running mine with 7700/7800 Dura Ace.

IMG_2377 by Dave The Golden Boy, on Flickr

IMG_1715 by Dave The Golden Boy, on Flickr

Lascauxcaveman 

As much as l like my Helicomatics, I certainly wouldn't try to upgrade them beyond sourcing a fresher 6-cog cassette for them. I've never looked at them closely enough to see if they can conceivably be taken apart and re-spaced with cogs added.

A new hub (or an all new wheel set) is what I'd go for in this case. Surrender your quaint French uniqueness and prepare to be assimilated. Resistance is futile!

dddd

I have upgraded a few bikes with Suntour Command shifters, and even did use a helicomatic 6-speed with the 7s shifter in indexing mode, since the Helicomatic freewheels have narrow cog spacing.
This was many years ago, and the old chains I was using allowed the occasional false-neutral effect just like when friction shifting with one of the Helicomatic freewheels and period Sedisport chain (what I was riding with today by the way).
With modern chain, either 8s or especially 9s varieties, many a mis-matched drivetrain can be made to shift unbelievably well, and I only wish that I had Shimano 9s chain available back when I was tinkering with Accushift equipment.


I wish I had a dollar for every time that I've needed to remind someone that expanding both sides of their frame at the dropouts at the same time is guaranteed to move the rear wheel off center. The chainstays must be bent and measured separately.
RJ bike guy gets a lot of hits but I sure wouldn't let that guy work on any bike that I cared about.
You can get a lot of profitable website hits just by breathing hard and pretending that you know what you are doing!

The Golden Boy 

I’ve learned a lot from RJ The Bike Guy’s videos.

Perhaps the biggest thing overall is “you can do it.”

old's'cool

FWIW, I used to shy away from tearing down a built wheel and reassembling, in order to re-use the hub, or the rim, depending on the case. But after reluctantly getting practice doing exactly that, my confidence has soared to the point that I now relish any excuse to deconstruct/reconstruct, or, if necessary, to build fresh from any combination of new/used/NOS components. I'm also not averse to re-using spokes, especially if none of the spokes from the original build has broken in fatigue. Extra marks if the spokes are stainless, but I was happy also to re-use a set of butted galvanized spokes, twice, rather than spend the money on new spokes, for subsequent budget wheel builds.
To get to the point, if you are fond of the rim but want to ditch the Helicomatic hub, do some reading up on wheel building, set aside a few hours on the weekend, and have at it!

tarsi 

I found a great deal on set of wheels (8 speed) and brifters however, from what I read the front shifter is for a 2 ring. Any tricks on making these work on my 3 ring cranks?

Kontact 

Nope.

The Golden Boy 

Do the Lance Armstrong thing and do your front shifting from the brifter and mount either a downtube or bar end shifter for your front shifter.

Not only do you go around only having the double shifter, you get around front indexing.

The Golden Boy 

BTW- I just noticed this post- The 720 has cantilever brakes.

Fortunately, the stock BR-MC70 cantilevers are adjustable enough to fit 700C wheels.

Be careful about wanting to get fancy and modern about the brakes- you might be tempted to think all the fancy technological developments in the past 30 years will make for better brakes on this bike- But there's a relatively few amount of brakes that will have the adjustability with the shorter distance between the canti posts. The BR-MC70s work, as do the M732 XT and the Suntour XC Pro brakes.

wrk101

The "trick" is to sell them and use the proceeds to buy a set of shifters that can handle a triple. Since it is a great deal, you should still do fine. Shimano and others have expanded their line of cheap STI levers. Bought right, you could actually make money on the sale/swap. I've used Microshift levers on several bikes.

You can sell a cosmetically nice, functioning, vintage 2x8 lever set for more than this:

https://www.ebay.com/itm/microSHIFT-...gAAOSw-3FZLbMi

tarsi 

Yes, thanks for the heads up. No plan to upgrade brakes at this time, just the shifting to brifters.

friday1970

Good catch. I don't think I've seen brakes like this personally. Centerpull cantilevers that just looks, well, odd. Still neat to see what was used in the past.

The Golden Boy 

I prefer the look of cantilevers to anything.

I think long centerpulls and sidepulls look awkward and gangly.

Cantilevers have to be placed properly to work and generally will always look purposeful and the good ones will look graceful while doing it.

tarsi 

Any issue with using brifters with the original cantilevers (ie pull amount)?

The Golden Boy 

Nope- only time you’d have to really worry is about using either V-brakes or V-bake specific components.

Now that I say that- I had a set of Aero Gran Compe levers that didn’t seem to play nice with the XT cantilevers- that could have just been me rather than an actual problem.

I’m currently using Tektro RRL levers with XC Pro cantilevers— and they work great!

Jon T

Any of you guys who have ditched your Helicomatic set ups still have the Helicomatic dork disk? Mine's cracked and I would like to replace it.
Thanks
Jon

tarsi 

Sorry but mine was missing. I am trying to decide what to do with the wheel set. Any interest in another set?

Jon T

Maybe the hub group if you're parting it out unless it's on the the cheap.
Jon

tarsi 

So you're still using the original front wheel I assume? Any issues with that one?

I'm considering re-lacing the rear with a 9 speed hub and keeping the front as-is. The only doubt I'm having is with staying at 27" vs updating to 700c. Is the limited tire selection/availability something I'm overthinking?