Public Group
Active 5 hours, 53 minutes ago
Group Leadership
- Group Administrators
-
-
This group is open to all registered members of the site.
WEAR IN ALUMINIUM RIMS
- This topic has 24 replies, 9 voices, and was last updated 8 years, 11 months ago by
.
-
Posts
-
has anyone experienced dangerous wear in aluminium rims? apparently they wear like discs on a car so obviously need replacing when they get too thin.the brompton rim thickness (used on f frame upgrades) cannot be measured with a standard vernier as there is a lip. on a small wheel you would expect them to wear faster as there is less area.of course it’s not a problem with disc and drum brakes and old style steel rims don’t wear they just rust!
I’ve had a rear wheel implode. Fortunately I had just started a ride and was going slowly on my 1996 Stumpjumper Mountain bike when it happened.
It was quite a shock because the ride terminated instantly and I had never experienced a rear implosion before.
The same thing happened to friend a few weeks later.
Now I clean rims and the face of brake blocks after every ride and try to minimise braking like driving the car.
On balance I would have thought that smaller wheels would wear out faster than larger ones.
I wonder if Brompton have any advice to offer on how to check rim thickness given that a standard vernier doesn’t work.
AlexJudith and I wear out the 406 rims on our Moultons in 2-3 years of 3-season riding as the Moultons don’t get used in Winter. The rims get replaced once they drop below 1.0mm wall thickness. That is about 2/3 the life of similar 700C rims.
There are rim thickness gauges available (which I use) and Chris Juden of the CTC has an article showing how to use a bent 2.0mm diameter spoke to measure around the lip on modern rims.
it doesn’t seem to be great technological leap forward, the use of aluminium rims over steel as they wear out so quickly when you think most of the original moultons are probably on their original wheels.personally i don’t think there is a great problem with the greater efficiency of aluminium in the wet as the small wheels wipe off the water quicker and the brakes then bite.when you consider the expense and trouble of having wheels relaced i’m sure there would be a market for stainless steel rims
Keep in mind that those 2-3 years is around 15,000km. For some folk, that distance might take quite a few years. As I mentioned, 700C rims only last us a year or so longer (we ride 700C bikes fair distances too). That difference in service life pretty much matches the difference in circumference.
Stopping with stainless rims isn’t wonderfully good with rim brakes and they are noticeably heavier than aluminium rims. Hub brakes of various sorts make for durable wheels but have limited application on Moultons.
Hi! Of course the Norwegian Moultons were all factory fitted with both front(drum) and rear(Duomatic) hub brakes and alloy rims. These original factory alloy rims are still going strong even though they will soon be FIFTY years old. That surely says a lot about the efficiency of hub brakes and alloy rims being used together.
I had a similar experience to Alex, only it was on my Speedsix ! I originally bought the Milremo 17″ X 1-1/4″ rims back in the late 70s from AM. He was probably designing the AM range at the time.
In the mid 80s, I acquired a Speedsix frame and started to build it up. The project was completed by about ’86, except that I could only get a 5 speed freewheel 28 hole rear derailluer hub back then.
I kept breaking spokes, until our late Chairman, Ian Hodgson rebuilt the wheels with small brass washers under the spoke heads. The rear rim lasted from that time to 2011.
They would probably still be OK – the front one is still on the bike – if I hadn’t bought a track pump (with gauge) and pumped the Wolbers up to 70psi.
(Previously, I’d only used a hand pump to get them up to ‘hard’!)
Shortly after setting out on a ride one day, as I was coming down a hill, I noticed the rear brake had developed a definite tight spot and it was getting worse. Before I could come to a halt, there was a very loud bang and I was on the back rim.
Inspection showed that the rim walls had splayed out, the tyre bead had ridden up the rimwall until the tube popped out. The brake block then burst the tube and the bead came away from the tyre..
As mentioned earlier, the front rim and tyre are still doing a fine job. Only I only pump it up to lower than design pressure and keep an eye on the straightness of the rims.
I got a replacement rear wheel from Graham Atwell. This time with a 6 speed cassette.
I suppose I should get the front rim replaced soon. It’s been in service nearly 30 years!it seems the norwegian’s got it right with hub brakes, to me the fact that a wheel can suddenly collapse is not the ideal scenario, especially if you have bought a secondhand bike.whilst on the subject of longevity how long do chains/sprockets last with deralliur systems? sturmey archer 3 speed internal gearhubs seem to last forever, i know someone who uses a bike with a 1939 hub daily, the hub has been in his family for 60 years and never taken apart
While the Sturmey Archer hub brakes are quite heavy and expensive ( though I admit you do notr have to buy a brake caliper) there are the Shimano Roller brakes, at first sight these are disc- brakes but in fact the disc is a cooling heatsink, the Roller brakes can be purchased for modest sums of money on ebay
i’ve been riding my dawes kingpin (folder 20 inch steel wheels) this week in the rain and i have to say i have had no problem braking in the wet
The link shows the device I use to measure the thickness of an alu rim. I usually would bin those rims when they reach 1mm in thickness.
i bought a digital vernier on ebay today which has a right angled “hook” on the end for measuring such things, i have a brand new brompton front wheel in my shed i’ll measure it to see what the rim thickness is.just to reiterate the thought of binning a rim and the expense and bother of having a new wheel built would seriously depress me. i would go for hub or disc brakes
vernier arrived today and measured an aluminium wheel i had lying around in the shed, didn’t look particularly worn and with a “beaded” rim similarly to a brompton wheel thickness of rim is 1.83mm average which doesn’t strike me as generous.i do have a brand new brompton rim somewhere i will measure
A good tool to measure rim thickness is an Iwanson gauge – which is originally designed for dental measurements. Avaiable for about a fiver from lots of suppliers on ebay.
i bought a new rigida rim for bromptons and measured the thickness it was 1.5mm on the walls and this is new, shockingly thin in my opinion, i’d be interested to know the thickness of the 60ish quid rims for newer 20 inch wheeled moultons
It is the chromium plating on the steel rim, which gives the exceptional twenty year or more resilience to wear of the traditional rim. Of course the brake blocks are the sacrificial item , being replaced during the life of the traditional steel rim,. Good aluminium rims have a indicator in the form of a rim groove, when the rim braking surface is worn to the depth of the groove, the rim is to be replaced
i think “rigida” are supposed to be a good make, i think disc brakes are the obvious way forward, the snag is most disc brakes have 36 holes for spokes and the brompton rims only have 28. not sure about 20 years for steel rims, i know someone who has a 50’s bike with the westwood stainless rims (no chrome plating) and still on original rims, used practically every day.the snag with disc brakes is the increased twisting on the front and rear forks, probably not an issue with the mk2 rear forks.to me replacing the rim , transporting to a wheelbuilder, picking up paying for and replacing is something i would rather do without in today’s time restricted world
i was googling this last week and it can be done but it is very specialist and with a strange radial spoke pattern and 3 or 4 different legths of spoke
i did actually download it last week it is an article by a lancaster university student who fitted a nexus 7 int gear hub and front disc brake to an f frame moulton, if anyone wants to see i am more than happy to email it as my computer skills are so lacking i cant put a link
I don’t know how much a a lecturer in the Department of Mathematics and Statistics at Lancaster University would thank you for calling him a ‘student’ But Dave Lucy’s page is here
http://www.maths.lancs.ac.uk/~lucy/hobbies/bicycles/bicycles.htmlthanks for that ian-mind you he does admit he kept getting the calculations wrong for the spoke lengths!
- You must be logged in to reply to this topic.