120mm OLD respacing
 

Looking for a bit of advice on spacing on my old Frejus. I am in the process of changing out the rear derailleur and freewheel to something this old guy can handle. Stock of course is 120mm axle. Frame is closer to 121.5-122mm. I need close to 2mm on the DS for the slightly thicker freewheel body on a Shimano 14-28 five speed freewheel and for the locknut on a vintage suntour 7 RD.

How much "off" would I be and would it really be noticeable to just space the DS. I have a 1.8mm washer that will do the trick. Would I even notice the dish? Conversely, I could easily put another of the same washers on the other side and spring the frame ever so slightly; less than 2mm.

Just wondering which way to go. Of course, I am saving all the old parts.

@sd5782, ideally, the front wheel and rear wheel track in line with each other. Keeping the rear wheel centered on the head and seat tube and having the dropouts parallel with each other is a good start.

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Understandable of course, and that jig and measuring is great too. I believe I saw a string method before too. I kinda wondered how much a mm or two would be noticed if at all for a casual rider going less than 30 mph.

Rear dropout spacing already almost 122mm, so when closing skewer is it assumed the 2mm difference would be taken up evenly from both sides? One could measure with no wheel mounted, and then locked in at 122 I guess to see, but that is probably greater precision than I could measure.

Perhaps I will look into Sheldon site for string method, but would have to take off fender too. I may just try one DS spacer and be happy dropouts aren’t spread or compressed. Recentering the axle then would then leave an equal axle protrusion of maybe 3.5-4mm.

Just respace (cold set) the frame normally. There are two basic home methods. Sheldon uses a 2x4. The new youtube guys use a long bolt in the dropouts and a series of nuts and washers. (I think this method is easier.) Pick one and go for it. Use Sheldon's string test to make sure the frame is straight. And yes, you'll have to redish the wheel.

If you don't want to respace, just add the spacer and take it to a shop to get it redished and trued.

Minor redishing is (I have heard, never done it), on a true wheel, often accomplished simply by tightening the drive-side spokes uniformly. It doesn't take much to move the rim over.

Looked at the Sheldon string measuring method with string going from dropouts to headtube and measuring string at seat tube. I did that and interestingly it was off just a bit and adding the 1.8 mm spacer to the drive side actually evened things out. That is also about the amount that the dropouts were over the nominal120mm. Lucky coincidence I guess as that suited what I was trying to accomplish anyhow.

Back kinda to the rest of the question as to how noticeable the ride is when it is off just a wee bit. I know I rode my old Supersport for decades with the dish off from trying to true it and not knowing any better about 30 years ago as a youngster. Perhaps a heavy bike on old Kendas doesn’t show minor stuff, or I don’t/didn’t have a feel for it. I know just a bit more now and am also willing to learn more too. Of course, an old Schwinn in the flatlands here is a whole different story than flying down a mountain at 40mph on a bit more of a premium bike.

@sd5782, it's possible you'll notice, but it's not probable.

I've used strings of various types to layout buildings with plumb-bobs, chalk lines, and such. The margin of error when laying out walls is miniscule but for a bicycle frame, the string method will only give you a general idea, but nothing to inspire confidence.

Under normal riding conditions, a frame that is out of alignment won't be noticeable or dangerous, but cruising down a hill at higher speeds could cause the bike to wobble.

Built a lot of wheels with a less than precise vintage about 86 Park consumer grade truing stand and until a couple years ago, I adjusted dish by flipping the wheel in the stand though I knew that the stand wouldn't maintain it's position through the flip. Just kep t flipping and adjusting till it seemed close. Never had a problem with the wheels in the bikes, never had a handling problem and they always road true no hands. So, a couple years ago got a wild hare and made a useable and pretty accurate dishing tool and started using it. Found out that all the wheels I had built were 1-3 mm off. None was correct. Couldn't sleep for a week worrying about it. Moral is, if you dish properly or even get pretty close with whatever method you use, you'll likely be ok even if it's not perfect. That being said, if you check it and adjust, you won't have to worry, won't keep yourself up all night and will have miles and miles of happy cycling.

...to do this with any hope of accuracy, you really need to have the frame up where you can see it and work on it easily, and at least the BB ought to be out.
Both wheels will, of course, be removed. It's a lot easier to do on a bare frame, without the fork flopping around as an extra hassle. Here are pictures I took recently on a current project.


...you probably won't notice. Try it and see. You can always sting it up later if it's already built up.

...using a long bolt (or anything, really) to respace a frame or a fork works OK, until you get to that one where you bust the spot where the fork end or dropout is brazed into the steel tubing. I did this once. It's not much fun. The frame ends of those guys are just in there with some brazing material . The crimped tubing itself won't hold them if the brazing happens to pop loose. You are much safer in your approach if you do this with something that grabs the stays orr fork legs themselves. On a lot of bikes, you can even use your hands and body weight, pushing or pulling on both stays on one side, or a fork leg.

But it's a lot easier to do with a lever arm with an adjustable set of hooks, modeled after the one Park makes and sells. You can make an acceptable substitute that will work with a piece of wood and a vinyl covered hook that bolts through it. Pad the other end with something to protect the paint. If you want to go fancy, you can wrap the handle end. :)

Thanks all. Kind of what I was thinking. Fun to learn stuff, but that opens up other cans of worms. Sometimes ignorance is bliss. Actually bike was up in stand with wheel and RD off. String around headtube to rear dropouts. Just a slight variance to one side. Spacer added which brought that side out which should have kept the centerline of the wheel the same as it was. Not real precise, but was reassuring to see it looking as it should. Now to set up the slightly less vintage RD to handle the 28 tooth freewheel. Still will be 5 speed vintage, but hopefully better shifting than the campy Gran Sport. Vintage is nice, and I have read posts of others having luck with the Gran Sport, but I haven’t.

...Gran Sport was a wonderful advance in 1951, with its parallelogram design. There are way better derailleur designs available in the used parts market right now that work way better. If they're available to you, just about any Suntour derailleur from the 70's works better. Even the lesser ones.


You can do a double check on where your wheel is running in the rear triangle relative to center plane by simply running a long straightedge along the head tube/seat tube line on one side or the other. See where it lands on the rim (works better with tyre off). Then do it on the other side. Compare results.


You can even eyeball it (roughly) with the wheel in the frame, and the bike in a stand turned upside down. You want your rear wheel/tyre to look like it's centered relative to the seat tube, when viewed with one eye open, square on and centered to the bike. That's how I usually set the adjuster screws in the dropouts, when a bike has them.