Rim thickness - worn out?

[Mick F]

Thanks guys.
Food for thought.

Riding in the wet is a normal thing. It doesn't have to be raining, but some of the roads and lanes are tree-lined and shady and damp.
Also, a small-wheeled bike gets muck and damp on the wheels much more than a big-wheeled bike.

There are three main disadvantages of a Moulton due to the small wheels.
One, it has small wheels so the tyres wear out faster.
Two, it has small wheels so the brakes and rims wear out faster.
Three, it's a heavy and sluggish ride ............ but that's more to do with the suspension and the frame, but the wheels still need to go up and down over the bumps and are not as efficient at it as big wheels.

Other than those, it's a delight to ride. Comfortable, quirky, and enjoyable.

[531colin]

…. Duh....

I suspect that rim manufacturers make their living supplying rims for new bikes and "upgrade" wheels.
These people actually want to save a few milligrams, they aren't bothered by longevity, they like the appearance of a shiny machined braking surface next to a painted surface. Equally, they don't want returns because the brakes squeal, or judder, or pulse, or because the paint wears off the brake track unevenly.
I also suspect that very few bicycles are actually ridden far enough to wear out a set of rims, and that the tiny minority of people who build and maintain their wheels (and hubs) correctly so that a re-rim is economically viable do not represent an opportunity for a rim manufacturer to make a living.

[Mick F]

Right, it seems that I have some leeway yet.
Not put the rear wheel back together yet, but that'll happen soon. Not well enough to ride at the moment and still taking the tablets.

I've been surfing the 'net to find better? cheaper? different rims than the Sun C18 from SJS.
https://www.sjscycles.co.uk/rims-tape/2 ... im-silver/
............ but I can't.
I want 28h and 36h.

Option One - interesting!
I still have the pair of 28h Moulton rims which being black offended my eye to start with.
https://fudgescyclestore.com/product/mo ... 406_20_rim
I fitted a SA 3sp CS-RF3 on the rear and they only come in 36h in UK.
http://www.sturmey-archer.com/en/produc ... rf3-silver
So this meant a new rim. Bought a new 28h for the front to match and fitted a hub dynamo at the same time.

My option therefore, is to re-fit the front Moulton (black) rim on the front, and see if I can lace up the Moulton 28h rear to the 36h SA 3sp.
Sounds like a good little task, and interesting too and will keep me on the road for some months and preclude paying out £70odd for two new CR18s.

Option Two.
Wear the CR18s out and meanwhile buy new ones ready for when/if needed.

Advice gratefully received!

[9494arnold]

Do you favour the front or rear brake?
There's a possibility front rim may have more wear. Would it be an idea to check whilst it's in pieces.
I have only ever dumped front wheels for brake track wear /rim thickness but I ride Trikes which have all the braking on the front wheel (generally) . I actually confiscated a friends front wheel off his trike ;he's not heavily into maintenance) because I considered it unsafe .
(I did supply a replacement)
I don't want either, but I think I would opt for a rear wheel failure as opposed to front.
I was next to a Tandem at a junction when the back wheel let go.
We had been on a quite technical descent about 1/2 an hour beforehand.
Could have been disastorous.
I know there's a lot going on on a Moulton, would disc brakes be feasible/ desireable?
( Rims designed for Disc Brakes are generally not quite so substantial in the braking area , if you went disc with a standard rim your wheels would be pretty bullet proof. Just a thought)

[Mick F]

I'm a both brakes person. Modulate as I go. I do it completely subconsciously.
Recently though, when I saw the rear rim so marginal, I've been letting the front do more work, but the front is nearly as bad as the rear. As the rear is 1.1mm, I would expect - but not going to bother to measure it - that it'll be 1.2mm. Both rims are very concave on the brake tracks.

As for disc brakes, it's an expensive mod.
I would need two new hubs to start with - hub dynamo as well as a SA3sp - then the brazing and painting of the frame, then the disc brakes themselves.

I have considered it and there are Moulton TSRs with discs, so it is feasible. Should have been done right at the start. I've already spent a king's ransom on the bike already getting it so it's a good bike to ride. I'm not getting any younger, so this bike as it is will see me out even if I have to buy new rims every 8,000miles. The tyres don't last long either!

[Mick F]

Question:
Can't get my head round this.

If the wear limit was (say) 1mm on a given rim, could this figure be correct for all diameters of rim?

The smaller the rim, the more wear it could take before collapse?
Correct .................... or not?

[Brucey]

yes sort of, provided that braking (squeezing) loads and tyre width/ pressures are the same.

Thing is, it won't be the case that those things are entirely independent of wheel size; the brakes squeeze the rim more often and (all else being equal) tyre pressures are liable to be higher on smaller wheels.

cheers

[Mick F]

Tyre pressures similar to Mercian 700c.
Braking is little old me on the same hills. Yes, Moulton is a few Kgs heavier but that doesn't make much difference I reckon.

The spin speed on small wheels is faster than on big wheels for any given road speed of course, but the speed of the top run of the wheel where the calliper brake is, is always twice the road speed.

The difference is, the wheel goes through the brake calliper more often then on a big wheel. That's why they wear more ........... as well as them getting muckier coz they're nearer to the ground ............... but you could argue that because the spin speed is faster, the muck is thrown off quicker .......... but they pick up muck quicker as well.

[philvantwo]

So why design a bike with small wheels and what's the point of buying one?
Can't ever remember seeing one round here in south Staffordshire, are there many about in Devon Mick F?

[nigelnightmare]

OPTION 3

Build new Disc braked wheels using CS-RK3 rear and a dynamo disk front.

I don't know if SA do a version of CS-RF3 with a drum brake but if they do You could go for...

...OPTION 4

Drum brakes front and rear using SA X-FDD front with a (CS-RF3 type) with drum brake rear.
And never worry about rims again!

[simonhill]

c) the machining is very often imperfect; often pieces of swarf are (invisibly) embedded in the surface, and then embed themselves in the brake blocks. The swarf-encrusted brake blocks will then wear the rims about ten times faster than normal. Triple duh

cheers

I often wondered why there were little bits of metal in my brake blocks.

Would you recommend 'cleaning up' a new machined rim eg with wire wool before using it?

[Mick F]

OPTION 3
Build new Disc braked wheels using CS-RK3 rear and a dynamo disk front.
I don't know if SA do a version of CS-RF3 with a drum brake but if they do You could go for...

...OPTION 4
Drum brakes front and rear using SA X-FDD front with a (CS-RF3 type) with drum brake rear.
And never worry about rims again!

Both of those are financially extreme. If money was no object, I'd have done it by now.

I could use the dyno hub on Mercian, and buy the CS-RF3 disk version and a dic version of the dyno hub. Both are available at circa £100 each.
https://www.sjscycles.co.uk/hubs-intern ... sette-hub/
https://www.spacycles.co.uk/m2b0s133p30 ... -Bolt-Disc

Then, the frame needs stripping down and braze-ons fitted on the front fork and rear triangle, then respraying.
Then buying the disc callipers and disc brakes.
Dunno about the brazing spraying costs, but parts alone could come three hundred quids or so. At least can build my own wheels using the existing spokes. Still have to buy new rims as it is, so that doesn't come into the conversion costs.

Is £300+ worth it?
Could be £400?



As for respraying, the Moulton TSR comes apart into:
1. rear triangle
2. rear frame
3. front frame
4. front suspension fork
5. steering front fork

Five parts that could be five completely different colours!!!!

[Mick F]

My Moulton TSR rims are Sun CR18 406 in silver.
https://www.sjscycles.co.uk/rims-tape/2 ... im-silver/
They've done 7,200miles and showing signs or wear on the brake tracks.

Just had another look at my records and I'm wrong. I was looking at the total miles done.

Facts:
Bike supplied with black Moulton rims. After exactly 3008miles, I fitted the Sun CR18 rims. I still have the empty Moulton rims. Yet to measure them, but I will and report back.

The Sun CR18 rims have done exactly 4,159miles. I doubt they'll manage 5,000miles.
1.1mm thickness seems very thin to me.

[Mick F]

Bike supplied with black Moulton rims. After exactly 3008miles, I fitted the Sun CR18 rims. I still have the empty Moulton rims. Yet to measure them, but I will and report back.

1.5mm and 1.6mm
1.5mm was probably the rear one.


So .............. if we consider that 406 rims be they Moulton MT20 or SunCR18 wear similarly - not fact but maybe similar?
The rims wear 0.4mm per 1,000miles.

This would make the rims 2mm thick when brand new.
Does this sound correct?

Is my arithmetic about ball-park?

[reohn2]

So why design a bike with small wheels and what's the point of buying one? ........

They do have their uses but it's limited.
The suspension on the Moulton design was to overcome the disadvantages of small wheels,problem is the small wheels throws up many other problems.
It's why Moultons are so niche,they have a following but it's a small one.
Personally I've never been convinced,,Mick's experiment with his has proved it to me.