Presta/Schrader Adapter

[StuntPilot]

A while back after reading about Presta valve inner tube availability when cycle touring, I decided to drill the Andra 30 rims on my Raven Tour to ensure that they could accept Schrader valve inner tubes if Presta valve inner tubes could not be found.

I purchased a few adapters ...

https://www.sjscycles.co.uk/rims-tape/wheels-manufacturing-presta-tube-stem-saver-fits-schrader-rims/

On my current tour down through Europe, when on one occasion I needed to remove the inner tube from the wheel, the valve adapter had oxidised firmly bonding the valve stem to the adapter and to the wheel itself! Only a bit of petrol and lubricant, and some time and force allowed the removal of the inner tube and valve adapter from the wheel. This could have been a show stopper if I had actually had a puncture en route. The inner tube valve was damaged during removal. A new inner tube was required as a result.

My advice would be to use only the plastic e.g. Mavic valve adapters to avoid this problem.

https://www.sjscycles.co.uk/rims-tape/mavic-rim-valve-hole-drilling-converter-insert-schraeder-to-presta/

The Wheels Manufacturing adapters are well made, but the oxidation bonding that can occur could prove a problem on a longer tour. Another solution is to use Copper Ease to hinder the oxidation and the bonding of the valve to the adapter and wheel.

[Danneaux]

Your experience mirrors my own past experience in this area, Richard.

I prefer to run presto valves in rims drilled for them, and carry spares rather than go for Schrader drilling, but some of my bikes came predrilled for Schraeder, natively too large for my presto valves (Note: The holes themselves are not so much "too large" as the smaller prestas fit fine. Rather,  the problem comes when pumping in air or at lower pressures, when the rubber valve base may become uncentered and rub through on the hole edge).

After a similar cold-welding incident with the Wheels Mfg adapters, I found my solution in soft vinyl (not rubber, which soon broke down under UV) grommets from the local electronic supplier. A whole sack of 20 or so cost only a bit over one US Dollar. They were quick and easy to fit and worked well with the knurled round presta valve locator nuts. As I recall, they had a 1/4in pass-through (hole) which proved a fine fit for the presto valves. The grommets last a long time; some of mine have been in for most of a decade.

On some rims with a narrow center channel, I just trimmed the sides of the inner grommet face and this made for a flat seating in the rim well, under the rim strip.

A pair of these vinyl grommets are doing duty on my tandem while touring now.

All the best,

Dan.

[StuntPilot]

Thanks for the info Dan.

Do have a link to the type of vinyl adapters your are talking about. Maybe I can source similar on my return home.

[mickeg]

I also use the Wheels Manufacturing ones.

I had a tube suddenly cut very close to the valve stem, I was standing next to the bike when I suddenly heard air leaking out of the wheel.  A friend of mine that works as a bike mechanic was there at the time, he commented that the sharp edge of the adapter can cut tubes.  I did not think it was that sharp, but since then I have filed down the edges a bit and used a counter-sink to smooth it a bit.  I also put a small piece of inner tube rubber with a small hole cut for the stem over the stem before I put the tube on the rims, that extra piece of rubber is intended to protect the tube a bit better from the adapter.

[Danneaux]

Okay, Richard, I'm home now and can get at my things...! 

The vinyl grommets I use as valve washers to resize my Schraeder-drilled rims to Presta size valves are commonly sold here (USA) by electronics stores as "3/8in vinyl grommets".

That means the hole to be filled is 3/8in, the bore is 1/4in, the OD is 1/2in, and the groove to center the grommet is 1/16in.

In metric sizes, this all translates roughly to 9.5mm x 6mm x 12.7mm x 1.6mm

The 1/4in bore is slightly tight on the valve with first use, but becomes a good fit after the first tube change. The 1/16 groove nicely centers the grommet on every rim I've tried one in because the vinyl is flexible. I've had no issues with UV breakdown or hardening/cracking as with rubber, and the vinyl grommets have survived well over a decade in some of my rim applications. They are one of those small things I have found to be inexpensive but work well. They completely put an end to valve decapitation for me and also solved the problem of galvanic welding between aluminum adapters and the rim.

Here is a link to one site that offers them; they are commonly available for little cost online and in electronics stores:
http://www.wiringdepot.com/store/p/1541-3/8-Grommets.aspx?feed=Froogle&matchtype=&network=g&device=c&adposition=1o4&keyword=&gclid=CKHa5sfp1s8CFQp3fgodjVUMkw

Sorry for the less than crisp photos, such things really bug me. It is raining cats and dogs here and it is hard to get enough light in the garage today to really see what I am shooting in the shadows, nevermind good depth-of-field.

All the best,

Dan.

[jul]

Do you think these ones can make the job properly ?

https://www.bike-components.de/fr/Mavic/Ventillochreduzierhuelse-10-Stueck-Auslaufmodell-p11627/universal-universal-o10001/

[Danneaux]

Do you think these ones can make the job properly ?

Yes, I think so, Julien! 

All the best,

Dan.

[jul]

Fine 

[Javier]

I would not compromise the integrity of my rim by drilling a larger hole just for the sake of the very unlikely event of lack of availability of Presta tubes during touring. If the worst happens, and there is no Presta tubes, then I can always get drilled the rim, as any basic workshop in the most remote place of the planet has a drill or a round file.