Rim thickness - worn out?

[ElCani]

I just had a Mavic Open SUP CD rim split on me, after over-pressuring (135 PSI) a new tyre in order get the bead to seat properly. Very annoying as the wheelset is very smart, nice shiny Shimano 600 hubs laced with DB spokes to the grey Mavics. The retro build was nearly done, now I have to try and find a matching rim and rebuild the wheel...

The rim didn’t appear that worn, no real sign of concavity, but I haven’t measured it yet.

[Mick F]

Maybe MickF should look for a double walled rim.

I'm all ears if you could find any rims in 406 size.
I desire (generally) silver rather than black, but any colour is fine - even black at a push.
Must be 36h as well as 28h.

Only ones fitting the bill are Mouton MT20 and Sun CR18. ............ but perhaps Moulton MT20 don't come in 36h.
I'm open to other makes if you know any.

[Samuel D]

I just had a Mavic Open SUP CD rim split on me, after over-pressuring (135 PSI) a new tyre in order get the bead to seat properly.

What size tyre? Wider ones exert a greater spreading force on the rim lips for a given pressure. Mavic specifies different max pressures for different tyre sizes for this reason.

[ElCani]

I just had a Mavic Open SUP CD rim split on me, after over-pressuring (135 PSI) a new tyre in order get the bead to seat properly.

What size tyre? Wider ones exert a greater spreading force on the rim lips for a given pressure. Mavic specifies different max pressures for different tyre sizes for this reason.

28mm Panaracer Race C Evo Classic. Measured at 26mm on the Open SUP rims.

[Samuel D]

Interesting. If I recall correctly, Mavic specified 116 PSI as the max pressure for a 28 mm tyre on the last Mavic Open Pro C I bought (non-CD). So, especially if your tyre was 26 mm, you didn’t greatly exceed that. I would have expected a greater margin of safety.

[ElCani]

Yeah... the wheelset was bought second-hand, so I don’t know its history. I’ll report back with a rim-thickness measurement at some point.

[Mick F]

Just checked front tyre.
A couple of cuts down to the canvass. Been used quite a bit. Continental GP.
Took it off and fitted a pre-used Schwalbe Durano. Not a nice tyre, but ok on the front I suppose.

I measured the front CR18 in the process.
1.2mm .............. the rear was 1.1mm.

[cycle tramp]

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 forkoriginal.jpg

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

Six really great things about bicycles with small wheels ;
Really easy to get low gears without trying too hard, they accelerate well, there's loads more room for luggage, drum brakes work really well., they're super strong and thanks to bmx there's all sorts of different tyres out there
....if I was starting cycle touring from start I would favour a 20 inch wheel size for all the above(however it's too late as I've a stock pile of frames which use a 26 inch wheel size) - having tried drum brakes I wouldn't go back to rim brakes just for the convenience. However such a measure is not without cost, especially when you consider things like frame alterations (although I saved a bit and just used the mounting brackets that came with the brakes, thus saving the cost of frame alterations and respray)
...of course one could convert piecemeal - if rear braking is favoured then just use a rear drum brake and keep the front brake as a rim brake... or vice versa
The other thing about drum brakes is that while the initial cost can be eye watering, it could be seen as a medium term investment, as you no longer have to pay for brake blocks or rims, plus you save a bit of time not having to measure rim thickness or fuss over rim block adjustment or renewal.

[mig]

Maybe MickF should look for a double walled rim.

I'm all ears if you could find any rims in 406 size.
I desire (generally) silver rather than black, but any colour is fine - even black at a push.
Must be 36h as well as 28h.

Only ones fitting the bill are Mouton MT20 and Sun CR18. ............ but perhaps Moulton MT20 don't come in 36h.
I'm open to other makes if you know any.

https://www.ebay.co.uk/itm/Weinmann-Amazon-20-BMX-Bike-Rims-Dual-Wall-Alloy-20-406-X-24mm-36-Spoke-Sand/202678984079?hash=item2f309bdd8f:m:mG79BJGvAonboX9au3Hocmg&var=502774285535

[Brucey]

Suggestion; why not fit a front hub brake? A bit of engineering required of course, but not too expensive, and you would then need only 36H rims in the future, and half as many of them if you are routinely wearing them out. If you bias the braking more to the front you could keep the wear off the rear rim more too...?

cheers

[Mick F]

Suggestion; why not fit a front hub brake? A bit of engineering required of course, but not too expensive, and you would then need only 36H rims in the future, and half as many of them if you are routinely wearing them out. If you bias the braking more to the front you could keep the wear off the rear rim more too...?

The issue is the front hub dynamo and the rear SA CS-RF3.
Any change in braking systems, puts the cost up. I won't break the bank, but it's a big step.
I fitted roller brakes to our mixte bike and made clamp-on clamps for the reaction arms out of brass strip. Braze-ons not required, so no doubt it's possible for drums.

https://www.ebay.co.uk/itm/Weinmann-Amazon-20-BMX-Bike-Rims-Dual-Wall-Alloy-20-406-X-24mm-36-Spoke-Sand/202678984079?hash=item2f309bdd8f:m:mG79BJGvAonboX9au3Hocmg&var=502774285535

Excellent!!!
Trouble is though, only in 36h.

I could buy a new hub dynamo in 36h for £69 from Spa and sell my 28h to help.
https://www.spacycles.co.uk/m2b0s133p30 ... YNAMO-PV-8

A pair of those Amazon rims for £26 + £69 + £4 P+P = £99
I'd need more spokes or different length ones, but I do have some spares I think.

Two rims 28h and 36h Sun CR18 from SJS = £34.99 x 2 + £5 P+P = £74.98

The advantage of the Amazon rims, is that they are CHEAP.
I could buy two pairs and have a pair for the future just in case the supply dries up.


Can I fit a 36h rim on a 28h hub?
That would save £73.

[ElCani]

Looks like the crack in my rim was already present, hidden under rim tape. Certainly doesn't look fresh when viewed from the inside, plenty of corrosion around. I've never used these wheels, despite owning them for about five years! Oh well.

[mig]

https://www.ebay.co.uk/itm/233077970600

https://www.ebay.co.uk/i/233279111093?chn=ps&var=532781345168&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=532781345168_233279111093&targetid=594652176440&device=c&mktype=pla&googleloc=9046636&campaignid=6619151996&mkgroupid=84510981568&rlsatarget=pla-594652176440&abcId=1140496&merchantid=113493004&gclid=EAIaIQobChMIyqH2uqyg5QIVD-R3Ch1gog7AEAQYAiABEgLh5PD_BwE

[mig]

this is also a 406 rim

https://www.ebay.co.uk/i/400912161990?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=400912161990&targetid=522579786463&device=c&mktype=pla&googleloc=9046636&poi=&campaignid=6744139827&mkgroupid=78343140366&rlsatarget=pla-522579786463&abcId=1139126&merchantid=7253514&gclid=EAIaIQobChMIyqH2uqyg5QIVD-R3Ch1gog7AEAQYDyABEgJFRPD_BwE

no new spokes required at all with that one.

[NATURAL ANKLING]

Hi,
I know how diligent Mick is in keeping accounts.
Both of my skip trainers cost me about £100 each to do 5000 miles each.
they have been maintained and built with parts from the tip.

I will give you one of my frames and sell you the rest for £30.
Then you can see if you can squeeze out the mileage at a budget, You can add labour costs if you want, let's say 5p an hour.
Be interesting to see how you go.
Or simply start a project with your discarded parts.