jpaschall

Spot on again, the lower race is in rougher shape. I'll take the advice, thanks!

The Golden Boy 

So where are you at with this guy?

(I'm just fishing for more pix!)

jpaschall

Stripped to the cranks/bb and waiting on a lockring tool to come in at my shop. Also need to find a socket that will fit in these cranks, as my 15mm socket is too thick to fit in the hole. I know park makes a special tool, but are there any regular sockets that will fit? Once I get the crank pulled I'll snap some more pics.

I've been doing a lot of planning and thinking about where I want to go with this. Beginning to think that going to 700c wheels is a good idea, but not sure which direction to go. I'm a pretty big guy (6'2 250) and am wanting to do some camping/light touring with this bike starting in the spring. I know Dyads and Mavic A719 rims are considered to be good rims for a guy my size, but I am not familiar with what hubs I can get at 126mm spacing that are good looking, tough and affordable (though I suppose I could set the stays to 130mm to increase my options). If I do go this route I'll have to consult a shop on the cantilever situation.

Otherwise, I've just been doing a lot of reading on Park Tools and watching lots of instructional videos. Trying to build up my confidence that I can actually do this, haha! Tearing the bike down, every piece I took off increased my anxiety! But, I am starting to feel better about it after doing some reading.

jyl

I asked about the socket issue, and was told that some of the better quality sockets will be thin walled enough to fit. Sometimes people grind down a cheap socket to fit.

Back in the day Campagnolo and Park made special wrenches with a thin walled 15 mm socket for exactly this application. The Campy "peanut butter wrench" tool is expensive now; I finally broke down and bought one for $50 because I have a number of bikes with 15 mm crank bolts and figured the tool will fit in a saddlebag should I ever do touring and want to carry a complete tool set. I'm not sure the Park tool is still being made, I looked for it too.

Why wouldn't you re-use the existing hubs? Just get a rim with the same hole count and build, or have built, the wheels. For that matter, why replace the rims? You'll have to replace the brakes most likely, and that seems like unnecessary trouble and expense. I prefer 700C to 27" but not that much.

jpaschall

Worried about the documented problems with the Helicomatic freewheel. If those worries are unfounded or just paranoid I have no problems keeping the wheels with the bike. The chainstay clearance on the bike doesn't look huge, so I doubt I'd gain much room for fatter tires by switching to 700c. At my size, though, I am looking to have as fat a tire as possible.

Also, I'm going to start cleaning parts this week. Stem and seatpost have some rust, and the RD is caked in gunk around the jokey wheels. Anything I absolutely should not take apart for cleaning? I know I should be very careful taking the RD apart. I've also seen some mention using a crockpot for this step, what's that about?

jyl

I wonder about the benefit from fully disassembling a RD. They are pretty easy to clean and lube without doing that.

I got curious about the Helicomatic and so I read some threads here. Seems like some people hate them and some like them. Maybe I just have a lazy aversion to fixing what isn't broken. Also I am skeptical that a 1 mm leftward shift in the flanges would significantly weaken the wheels. Is the DS dish really any worse (less) than a modern 10 speed wheel? Don't know, just asking.

The Golden Boy 

I pretty much agree with @jyl about don't fix what's not broken. You should be able to clean most of the caked on gunk without too much disassembly.

That being said, if I *had to* take apart a DuoPar, I'd keep in mind there's a lot going on there:

bikemig 

I'd be sorely tempted to get rid of the Helicomatic wheels and go with 700c wheels as this is a more common size. The cantilevers may end up giving you a problem as the 700c wheels are a bit smaller in diameter but that can be fixed. For hubs, it is hard to beat phil wood which still makes a 126 mm hub. Alternatively, spread that frame (I can hear the cries of horror on this list at that idea, ). It's your bike though and a modern drive train is pretty sweet. Personally, I'd get the Phil freewheel hub (it's expensive) or a velo orange 126 mm rear hub (less than half the price of the Phil). Velo Orange also sells built up wheels.

Forgot about this hub, https://harriscyclery.net/product/qua...eleas-2544.htm.

Velo Mine sells built up wheels (both 700c and 27 inch) with these hubs. They're machine built but I've been happy with a pair of 26 inch wheels I picked up from them.

avzay66

I also have a trek 720, which I got for a bargain. Mine is a 1985, and came with 700c wheels/tires.

As for helicomatic hub, I have 2 of them on different bikes, and it never gave me any problems. What is the issue with these anyhow?

jpaschall

I will do my best to clean it up assembled. I figured that was the only thing I really needed to worry about disassembling. I will likely go with the VO hubs and perhaps their diagonale rims when I can save up $400 . For now, I'll clean up the stock wheels, as I could use the practice servicing hubs anyways. Don't the helicomatic hubs use a different ball bearing size? Resources for purchasing new bearings?

jpaschall

Looks like this Huret Duopar rear may be toast? There appears to be a bend in the cage at the upper jockey wheel that has gnarled said wheel. Have a look:



I imagine I could take the jockey wheel off and file down the rough spot?

The Golden Boy 

That is EXACTLY what happened with my DuoPar on my Trek 620.

https://www.bikeforums.net/classic-vi...v-commute.html

I replaced the DuoPar with an M735 Deore XT then a Suntour XC Pro and right now it sits with a really pretty Suntour XC Comp.






A few months ago, I finally sent the derailleur to @pastorbobnlnh who cleaned it up, sanded down the pulley and unbent the cage. I'm still afraid to use it- and truth be told, I'm still mad at it. The Suntour derailleurs I've been using are just much more dependable.

jyl

Yes, I'd file it off as you said. If you have a thin nail file, you may not even need to remove the pulley.

bikemig 

What do you use for a chain stay guard? It looks good. The Duopar can handle very wide ranging gearing but the Suntour derailleurs clearly shifted better. I rode across the country using a Duopar. It was dependable and it worked but you had to baby it a bit to get it to shift right.

The Golden Boy 

I did a twine wrap- just because I thought it looked nice- it does come off as a bit too precious- but from the chain goop on there, it's doing a job. Forum member @Catnap did something like that, but his way makes more sense and looks better- he wrapped the chainstay in electrical tape, put a thin layer of Elmer's glue and then did the twine wrap.

https://djcatnap.com/bridgestone-rb-t...-touring-bike/

The wraps on mine kept sliding, so I tightened it up the best I could and did a cloth tape end on each side. Catnap's looks better as it's a regular twine whip wrap.

I thought the DuoPar is a nice looking piece- it's pretty unique looking and the Sachs/Huret logo is very "business." It never really worked well on my 620. But the 720- with the Helicomatic Freewheel- it was absolutely the smoothest shifting bike I'd ever experienced. It changed gears so smoothly and efficiently I would seriously wonder if I missed the shift until I felt the load change. Unfortunately, that thing did something goofy, I still don't know what happened, but the chain went slack, it went over the big ring (chewed up my beautiful crank arm) and the RD arm turned backwards (the spring tension was on the other side)... it was a mess- and one that could only happen with a DuoPar. I went with the same M735 Deore XT on there for a while, and went to XC Pro again. Since I'm not doing Command Shifters yet, I'm giving thought of trying to set up the LeTech on there since I'm running the friction Barcons...

jpaschall

I'm going to try to fix the problem for now. I'll never know if I don't give it a shot. In the mean time I'll keep my eyes on Ebay for a Suntour long cage, probably a Vx GT or a Cyclone GT, as I like the way they look and they are well regarded.

Update: @Flog00 is coming through with a Suntour VGT Luxe RD. Can't wait! My father-in-law had a 15mm that fit the cranks, coming off tonight.

jpaschall

Got the cranks pulled off tonight! Now just waiting on my tool to come in to take the BB off and I can begin reassembly. Some pics as promised, though they aren't great. There are a few good size scratches that I will probably just go over with clear nail polish. The last picture shows the stubborn rust like build up on the TT that I couldn't get off. Will try rubbing compound before I do my final clean and polish. Also, there is some very old tape on one of the chainstays that is proving difficult to remove, any thoughts for removal?

jyl

The top tube looks like it has a bit of rust under the paint.

For the tape, Goof Off or similar solvent is good to get adhesive off. If the tape itself is stubborn, maybe try some careful heat, blow dryer level heat, not heat *** level heat, see if the tape softens at all.

Looks great!

jpaschall

Rainy day = cleaning small parts all day. You really can lose track of time cleaning this stuff up.

Cantis before (right) and after (left):


Stem before and after:


These melted one brake hoods are giving me some trouble. Will acetone do the trick?

vintagepedals

nice find! I had that same feeling when I got mine although it was a pure labor of love restoring it back to its glorious state. now, its been my weekend ride roaming around old downtown quite happy and fulfilled.

jpaschall

Got my lockring tool in, but now I need a spanner to remove the adjustable cup. Would like to remove the fixed cup too, so also needing a wrench for that. Anyone have experience with the Park Tool HCW-4?



Edit: Or is it really inadvisable to remove the fixed cup for my overhaul? If so, I'll just go with the SPA-1

jyl

Acetone should.

The Golden Boy 

@Flog00 The Patron Saint of 720 Owners.

mechanicmatt

I have experience with that or rather it's older brethren. It works, but it typically gets marred up from slipping. I have used the tool for a lot of eighties bike era bottom brackets so I think it is worth the investment. By loosening the fixed side, usually the whole system comes apart easier to evaluate and clean.

PS, I like the pin side over using the tuning fork type wrenches as well.

Did you ever get the cranks off? Sometimes the crank bolt looks 15mm and is really a 14mm, so you may double check.

JohnDThompson 

Ammonia will dissolve latex; you might try that.

It's not necessary unless you're planning on replacing the bottom bracket. Otherwise, just clean it in place.