reroll

Scotty of Star Trek fame once said, Captain, you cannot change the laws of physics!

A number of different bike frame manufacturers have done this, in particular for rear hubs, designing frame dropouts having a dropout spacing about halfway between two commonly used O.L.D. requirements, say, producing a 132.5mm dropout spacing to accommodate either a 130mm or a 135mm hub. Yet a compromise exists in that the mounting surfaces of the halfway-spaced dropouts would initially be parallel to each other BUT when those halfway-spaced dropouts get either pulled together slightly to fit a narrower hub or expanded outward slightly to fit a wider hub then their hub mounting surfaces would no longer be parallel to each other. To easily see this, with your elbows touching your sides and your arms straight out forward with palms parallel to each other, notice that by rotating your arms outward or inward the palms of your hands do not remain parallel to each other. Moreover, when dropouts are not parallel to each other they do not fully contact a hub's intended contact points as they then rest on either the forward side of the hub's contact points or the rearward side of the hub's contact points, ultimately meaning the hub's bearings, either cup and cone or sealed bearings, become eccentrically loaded, a fact which would raise the eyebrows of any mechanical engineer in the world, as an incorrect and faulty design!

Yet this halfway-spaced design has been in use for a long time and on a number of different bikes and I have been searching for any comparison of the durability and reliability of hubs used on parallel versus non-parallel dropouts but my searches have come up empty-handed as though there were not a noteworthy difference.

Would such an inquiry be of interest to Bike Forums members?

Ironfish653

That's because there is no noteworthy difference. There is no notable effect in anything outside of the most extreme use cases; and in those cases, typically other components fail first, long before asymmetric bearing race wear becomes an issue.

I'm sure this would be of interest to certain BeikForum members, particularly those who inhabit the far depths of the rabbit holes where correlation is causation, and magical thinking abounds.

*There are a lot of conditions in a mechanical system that can be conceptualized, even potentially observed, but if it's possible to measure it, once quantified, gets "lost in the noise" of real world operation.

Rolla

I'm sure there are those here who would love nothing better than to take a deep dive into this inconsequential minutiae and argue about it endlessly.

Your Star Trek reference ought to attract them like moths to a flame.

wolfchild

132.5 vs 135 is only 2.5 mm difference and is not significant enough to cause any issues on steel frames...I wouldn't do this on an aluminum or carbon frame.

Rick

Use dropout alignment tools to check the alignment. If they are not aligned and the frame is made of steel. You can align them.

reroll

Just to say so, I have now placed an order for a Surly Cross-Check which has Surly's 132.5mm Gnot-Rite dropout spacing and because I have not found any controversy or discussion about that I figure the odds are that all will go well as it has for so many others.

icemilkcoffee 

what hub are you planning to run? If it’s a Shimano hub, you can add/subtract spacers to make it exactly 132.5mm wide.

reroll

I have been thinking about doing just that, add/subtract spacers. I am a fan of older Shimano 8/9- and 8/9/10-speed hubs, LX FH-M570, Deore FH-T610 and 135mm others because they can have 4 or 5 mm less RH flange offset for building stronger wheels than modern hubs can and the add/subtract spacer plan would adapt nicely for the truly Frankenbike gear train I have in mind, with ~19 gear inch low gear, ~105 gear inch high gear with widely but fairly evenly spaced ratios in between, on 700c wheels.

79pmooney

The other approach would be to cold set the frame to the dropout spacing you want, then tweaking the dropouts to true with the tools. At 1.25 mm per side, the frames not gong to care. (I'd do this just to be a standard, easy to insert wheels width.)

For the fun or it, I calculated the angular deflection as you squeeze (or expand) the dropout width 2.5 mm. 0.2 degrees. I'm betting this is within "noise" for the hub bearings and measuring any difference in lifespan difficult.

But fixing haggling little "not quite right" issues - I'm doing several right now on my Mooney. Just had a frame builder cut a slot in the fork threads to capture the nib of a new brake hanger. (I've always filed them off and done the three plus hands job of adjusting the headset while holding the hanger centered. Bike's going to go back and have a threaded pump peg installed on the headtube (forgot to have the framebuilder do that while he had the frame to move another fixture) and correct the asymmetry of the Phil Wood BB. (Actually, add asymmetry. I went to order a 4mm asymmetrical from Phil. They said they had a symmetrical in stock and it would do 4mm without issue. Well, after paint, I want the chainrings a little further from my $$ paint job and 6mm just plain looks wrong! Frame builder has "slid" a bunch of Phil BB spindles for the tandem crowd back when many ran Phil.)

Germany_chris

I run 130 spaced hubs on my Cross Checks

reroll

Cold setting is an art, not a product which can be ordered from a catalog and 1.25mm is a rather close tolerance for cold setting. Surly framesets are made in Taiwan, which has earned a reputation for being able to produce top-quality commercial forks and frames, is a division of Quality Bicycle Products, the largest distributor of bicycle parts and accessories in the bicycle industry, so product quality control would likely be of top priority in Taiwan, which leads me to believe it would be better to leave their work intact and undisturbed and instead go the route of adding and subtracting spacers.



As was said, ya canna change the laws of physics. Bearings are designed to do a job having both axial and radial loads on them and the axial load is assumed to be evenly distributed, but non-parallel dropouts produce an unevenly distributed, eccentric axial load and yes, you are gambling on that being within the "noise" limit. And what I am doing here is banking on Taiwanese craftsmanship to produce parallel dropouts and then making my own hub OLD adjustments based on that, which seems a safe bet.

cyccommute 

It’s not an issue for aluminum nor carbon either. Both materials have some spring ability. Carbon won’t cold set but I suspect that it could be spread more than steel without issues.

You are right that it is a very small difference. So small, in fact, that it would probably be within the error of dropouts being parallel during manufacturing.

cyccommute 

In the real world not everything is going to operate within a five 9s tolerance. There “perfect” and then there is real life. If you are using a hub that has cup and cone bearings, you are likely going to have more error in the adjustment of the bearing than in how parallel the drops outs are since cup and cone bearings are adjusted to a high degree of accuracy.

But you said above that “1.25mm is a rather close tolerance for cold setting” and here you think you are going to be able to adjust to a 0.2° accuracy on the parallelness of the dropouts by hand in your own backyard? The tools we use to check how parallel the dropouts are probably has less accuracy than that.

Finally, bearings wear because there is some misalignment in all frames. Those and the cones are the only things you are going to need to worry about in terms of wear. They can be replaced.

This is small stuff. Don’t sweat the small stuff.

70sSanO

I’ve run the predecessor to that spacing, 128mm dropouts to run 126 or 130.

I would disagree on your uneven load due to the fact that QR, through axle, or nutted clamp the dropout firmly against the lock nut. There is enough flexibility in the frame to accommodate this.

There is one area, that might be a small issue, and that is the hanger not being straight. I have not heard, nor encountered, any problems, but if I were at all concerned that would be the only area.

John

79pmooney

It's a pretty good bet that your high quality Taiwanese frame has already been coldset. The heat from brazing or TIG welding distorts the steel. Then both the tubes and weld/braze filler contract. The odds of your frame being aligned to high standards after all this is fairly low, even with the best practices. Yes, unnecessary coldsets should be avoided but to get the frame to serve your purposes best? Well, there's just a century or more of precedent.

reroll

No, I am relying on a manufacturer to produce parallel dropouts and then adjusting the hub OLD would use presumably parallel spacers.

reroll

I have nothing against cold setting a steel frame but it is an art, yet Surly's Taiwanese frame makers would no doubt be artistic experts when it comes to cold setting.

reroll

You know about springiness, that when most things get bent they tend to spring back into their original shape, unless they get bent too far. A frame would have flexibility and when bent would also have that tendency to spring back into its original shape, within limits, and that springiness would also put a load on the bearings. In other words, just because a dropout gets bolted on to look straight and square does not eliminate any internal forces within the dropout material.

smd4

An “art?” Bending metal a couple millimeters?? Really??

79pmooney

There are many good mechanics with the skill. Any frame builder and lots of others. Ask around. I used to live in Boston and Belmont Wheelworks is still going strong. I'd have no concern about them doing it right but there are probably a couple hundred more mechanics in New England just as good. We had a mechanic at the shop I worked in back then with the touch. (He "shrank" my Fuji Pro warranty replacement from 126 to 120 so I could use my existing wheels. A shop in Seattle later spread my Mooney from 120 to 126 so I could go 7-speed. 1995 and maybe 25,000 miles ago. (I'd ask if the shop had a dropout alignment tool. If no, I'd pass on them. The tool doesn't tell you they know what they are doing but no tool or the words "you don't need it" would be a serious red flag.

Nothing wrong with re-spacing your wheel, But it would drive me nuts to have a bike where a standard wheel wasn't "right". Now I like my Miche track hubs with long axles that I can space to anything. (They come the track 120 standard. The ones I use with the Mooney I space to 126. Axle to spare to go to 130.)

reroll

Although now in Central Western Mass I lived in Boston '79 - '90 and averaged about 1,500 miles/year as a year round bicycle commuter. Belmont Wheelworks and its cousin Ace Wheel Works in Somerville are still around and doing well but I understand Peter Mooney has retired.


There would be good mechanics who could do well at cold spacing but I personally do not know any of them and so for me it becomes a roll of the dice, a gamble, as to which one of them would be good at that, or not, and a new frameset made by a reputable manufacturer seems my best option but of course even a new frame could be taken into my LBS for an alignment checkup.



That makes good sense, thank you, and I will remember that!



At least Surly is being straight-up honest about having Gnot-Rite rear dropout spacing on the Cross-Check but even that small amount of Gnot-Riteness has me wondering how to make it better. For a 10mm axle I can get 1, 2, 3 and 5mm spacers and could fabricate thinner spacers from shim stock to get the final spacing just right.

70sSanO

Lots and lots of people have cold set steel frames. There is not a lot of art to it.

The exception would be a 120mm to 130mm. But going from 132.5mm to 135 or 130 is not tough.

I’m not buying 1.25mm per side would cause any problems. You need to roll back the clock 50 years and see frame tolerances back then, and those Campy hubs that were used are just as smooth today; if maintained.

It is nonsense.

John

dedhed

You put a lot more faith in mass production consumer goods manufacturing methods than any quality engineer does. Mass product inherently includes tolerances that allow variations in items, especially non critical dimensions.
It's why lots of parts in systems are slotted.

reroll

Yes, I am relying on Surly's manufacturer to produce a correctly made frameset, but then I also have access to a bike shop having the same owner/manager since 1984 and once the frameset arrives it then goes into that shop for a complete inspection. If it passes inspection then I will be satisfied but if it does not then the frameset has a warranty which covers product defects, and so at this time I can afford to rely on Surly's manufacturer, pending future inspection.

dedhed

FIFY
Manufacturing variances within tolerances are not defects.