philbob57

I've got a 1973 MKM frame that I'd like to powdercoat, but I don't want to put money into it unless it's still good.

When I use my trainer (original turbotrainer ca. 1984), I notice the rear end moves side to side, pivoting on the bottom bracket. Is that common for Reynolds 531? Is the frame 'worn-out'?

At 75, I'm a slow rider; I usually ride at 12-13 mph, though at the end of 2019 I was cruising at 13-15. I don't notice whippiness on the road. Phantom shifts are rare, but that could be because I don't put out that much power.

Thoughts? Stick with this frame or look for something else?

Thanks.

Salamandrine 

Frames don't wear out, so put that idea to rest.

All frames flex to some degree. I'm not familiar with MKM, but it's possible if unlikely that it is built with an extra light gauge of 531. If and when you strip the frame down - no fork, no headset, weigh it accurately, and many of us here will be able to tell if it's unusually light. Ask. Depends on size too. 4.5 lbs or so is typical.

Frankly, for the riding you describe, it should be fine even if it is a superlight weight weenie frame.

blamester

Take it out and ride it on the road before you powder coat it. See if you like it. Try another bike. Don't waste time on a bike that you cannot set up right.
Frame stiffness shows up differently when it clamped in the trainer.
It won't have worn out.

Stevensb 

MKM made a number of different frames so perhaps you can post a picture to help identify what you have?

I ride an MKM Metcalfe BAR (mid 70s) and haven't noticed any sign of whippyness.

Cheers.

Brad

gugie 

Those Turbotrainers lock down the rear wheel at the dropout, so side forces flex the bottom bracket more than normal, and you notice it more since you don't have to pay attention to where you're riding.

531, SL, CrMo, any steel has the same modulues of elasticity (they all flext the same), differences in stiffness are due to geometry (wall thickness, tubing diameter, butted section length).

And, as Salamandrine notes, frames don't wear out and get less stiff, unless it develops a crack somewhere, which is somewhat rare.

0.2HP

As stated above, steel frames don't wear out, but they can get damaged in crashes or from other abuse. Carefully check where the chain stays are brazed to the bottom bracket, and all the brazes at the rear drop out. Any cracks can allow excess flex, which in turn will likely open the crack more and cause more flexing (progressive failure.) After that check for dents or creases anywhere in the chain stays or seat tubes; if severe enough these can flex. A bent frame may also flex too much, you can try to check this with string and straight edges, but the easy way is to see it you can ride it no hands.

Info on normal, non-damage-caused frame flex;

https://www.sheldonbrown.com/rinard/...frametest.html
https://www.sheldonbrown.com/frame-materials.html
https://www.sheldonbrown.com/brandt/frame-soft.html

Kuromori

To be pedantic, steel frames do fatigue, so they do "wear out" in a sense. People often don't get this because steel frames can often last a lifetime or two without any failure, and they often die some other kind of death before fatigue causes cracking. The idea that steel frames don't fatigue because steel has a fatigue limit is a fantasy fueled by people who have the romantic notion that steel is forever. So is the idea that steel doesn't fatigue because it isn't bent past the elastic limit, due to a misunderstanding of how breaking paperclips applies to bicycles. However this doesn't really change the material properties, it's just the source of frame cracks that show up and not caused by crashes or whatnot. The stronger the steel (in fatigue strength), the stiffer the frame (thicker tubes, smaller frames), and the lighter the usage (smooth roads, not being a pro sprinter), the more lifetimes a typical steel frame will last.

It might be worth noting that turbo trainers put a lot of stress on the dropouts especially if you try to sprint on them. It's a very rare but not unheard of occurrence for frames to break there on trainers. For a typical steel frame, this is a non-issue, but there are a few dropout designs that have a reputation for cracking in normal road use, and I wouldn't put them on a trainer.

As far as whippiness goes, if a frame doesn't feel whippy to you, then it's not whippy for you. Whippiness is not an inherent quality of a frame, stiffness is. Whippiness is when a frame is of inadequate stiffness to the rider riding it. If someone calls a frame whippy, either they mean they found the frame whippy, or they think the average rider would find the frame whippy.

CliffordK

My old bike... I think I need to work on the alignment some.

That is one issue with steel in comparison to other materials.

If a carbon fiber frame was straight when it left the factory, it will remain straight for the life of the bike.

On the other hand, over time (small mishaps) a steel bike may get out of alignment. That would certainly be something that I'd check before investing a bunch of money in a new build, although alignment can be fixed, probably even after powdercoating (in fact, there may be benefits of doing it after a heat cycle).

This gets me to whippiness. I really don't notice frame flex much while riding, although I have one titanium bike that I was having troubles getting the derailleur adjusted perfectly, and could induce chain rub with enough pedalling force.

Nonetheless, I can't inherently feel frame flex while pedalling (can some riders)? However, I have wondered if increasing frame stiffness in newer bikes has had a significant impact on rider performance (if that is important).

My old Colnago, however, felt very uncomfortable doing a 50 MPH downhill bomb a couple of years ago. Like I said, I need to work on alignment some, and we'll see if that helps. But, the whole frame seemed to flex with any change of positioning that I did.

I hit maybe a mile or so of rough road up in Portland during a paving project with my Funny Bike. Whew, I could see the whole frame wiggling and flexing as I rode, especially the fork. Not that it was necessarily bad.

That also brings up the point that a lot of people like some flex from the steel bikes with the idea that it improves the ride a little bit. And, the big thing in bike manufacturing now is to get the flex where one wants it, and not where one doesn't want' it.

repechage

An excuse to buy a Klein or Cannondale.

T-Mar

The OP is talking about a circa 1984 Turbotrainer. Back then, the trainers typically locked into the front wheel dropouts and had a BB support that could be moved forward or backwards and raised or lowered to accommodate the BB shell position. On the Turbotrainer, the BB shell was held down onto the cradle support only by a bungee style cord. which hooked onto the chain stay bridge. The front supports weren't very rigid and the BB support even less so. The bungee attachment would allow some bouncing and lateral BB movement when pedaling hard. It was very common to see lateral movement of the rear wheel due to flex and movement of the trainer stand and bouncing of the frame. It is inherent to the Turbotrainer design and has little, if anything, to do with frame flex..

Fahrenheit531 

I have three bikes, all 1970s, all 531. There is a noticeable difference in flex/whippiness between them, to the point where I briefly had concerns about the integrity of my Raleigh's frame. No issues, of course. Ride your bike off the trainer, see if you like it. If you do, proceed with restore/refurbish. Easy-peasy.

Kuromori

I'm not even sure how you could tell there was frame flex on that. Especially with the bungee instead of kickstand-like chainstay clamp ones.

philbob57

Thanks for the comforting information. As you can imagine, given my style of riding, I'm not worried about metal fatigue. I've never crashed it, and it hasn't been ridden in the rain much. I was a lot stronger and faster in '82 than I am now, when I was half my current age, and I always felt like it was more than stiff enough for me.

I was planning to ask RRB to remove the fixed parts of the headset and BB, and I was also planning to ask Mr. Boi if the frame looked OK.

I've ridden this bike since 1982; it has always been my only bike. If one can love an inanimate object, I've loved the bike since my first ride on it. It almost definitely is an MKM Dominator - https://www.mkm-cycles.co.uk/catalog...5vnf3ss22m95t7.

The ca. 1984 Turbotrainer I use is the first wind trainer on the market. It supports the bike at the bottom bracket and the front dropouts, so the rear triangle is free to swing any which way it can. It's a horrible-looking piece of equipment, but it has always done its job.

embankmentlb

Old C’dales work real nice on turbo trainers!

Wulf

I have one of those Turbotrainers exactly as pictured. I still use it. I traded my rollers for it since I couldn't stay upright on those.

philbob57

I would have included the photo below in my earlier post, but I used the wrong search argument, so I didn't find it.

The Skid-Lid version is far more refined than mine, which is: https://imgur.com/KrSxzIF

canklecat

My steel frame Ironman is flexy on the Cycleops trainer. No big deal, it's fine on the road.

I suspect a more secure trainer would reduce the side to side shifting. The Cycleops and similar trainers use a fairly primitive threaded adjustable bolt to support one quick release end, and a sliding locking clamp on the other side. The cups that hold the ends of the quick releases allow a lot of slop. So it's not so much the frame flexing as the entire bike shifting on the trainer. And there is some frame flex, especially the bottom bracket. Trainers with better supports probably shift less.

Salamandrine 

True, the reality is slightly more complex than steel doesn't fatigue unless it is bent past its elastic limit. Regardless, for practical purposes this fuzzy line isn't terribly pertinent to the OP's question. An old bike isn't going to get more flexible. As you point out, the properties aren't going to change. Steel bike frames really did not break very often, but on occasion they did. A drive side chainstay crack or adjoining rear dropout crack was the most common failure I used to see. Most people seem to think it was caused by flexing of the long end of the rear axle (freewheel hubs obviously), and I'm inclined to agree. Clearly in this situation the chainstay is not ever bent past its limit.

But enough geeking out. I agree with everyone else. The bike probably just seems flexy because of the turbo trainer.

aland2

I think you may find "modulues" is actually spelt "modulus". And how you can present the three attributes of wall thickness, tubing diameter and butted section length under the heading of geometry is beyond science.

gugie 

Ah, but you missed my mispelling of flex (see above).

Elastic modulus (thank you so kindly for pointing out the mispelling, which I often do when trying to peck out a reply on my phone rather than wait for a proper keyboard to reply) is a material property, whilst wall thickness, tubing diameter, and butted section length are properly described as variations of geometry, which are material independent.

It may be that it's been some time since my university training in mechanical engineering, but I do remember a bit of it now and then.

BFisher

Not that gugie, or anyone else, needs me to do this, but your post is out of line and ignorant.

"Geometry: the branch of mathematics that deals with the deduction of the properties, measurement, and relationships of points, lines, angles, and figures in space from their defining conditions by means of certain assumed properties of space.
-any specific system of this that operates in accordance with a specific set of assumptions:Euclidean geometry.
-the study of this branch of mathematics.
-a book on this study, especially a textbook.
-the shape or form of a surface or solid. (Like diameter, wall thickness, and butted sections of tubing)
-a design or arrangement of objects in simple rectilinear or curvilinear form."

"In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere."

T-Mar

What you have is a Racer-Mate II. While cyclists generically apply the term" turbotrainer" to all simulated wind load trainers, Turbotrainer was a trademark owned by Skid Lid. It's another case where one brand dominates the market during the introduction of a new product type, to the point where the name is applied to all brands. For instance, it's common to refer to all facial tissue as Kleenex and all snowmobiles as Ski-Doos, even though they are specific, trademarked brands.

Regardless, the Racer-Mate II suffers the same ills as the Turbotrainer and other simulated wind load trainers of this style. The rear wheel will dance on the roller and has little, if any, to do with frame flex.

T-Mar

It is true that steel has a stress limit that, if not exceeded, will not result in fatigue. However, this fatigue limit can be lowered substantially by heat. Overheating a frame during brazing can result in the fatigue limit be lowered to the point where normally experienced stress will exceed the limit and cause fatigue failures. This is why high grade frames are often manufactured with silver solder. It has a lower melting point, reducing the probability of overheating. It is also why lightweight frames should be built by experienced craftsman. The thinner the tubing, the easier it is to overheat, so you want somebody with a lot of experience in controlling the heating. You can't tell if a frame has been overheated until it starts to fail, so you're putting your faith in the reputation of the frame builder.

philbob57

Thanks, T-Mar, for remembering and posting the actual name of the product. Count me among those who appreciate your willingness to share your knowledge of bicycling history.

T-Mar

I've got an old Racer-Mate advertisement from 1984 that I'll try to remember to scan, the next time I"m at the library. Seven Deadly Sins: My Pursuit of Lance Armstrong is due for return mid-week, so look for it around that time. Fortunately, I'd previously scanned the Turbotrainer advertisement.