Inner tubes for Dawes Kingpin?

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HannahR
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Joined: 22 Sep 2012, 1:15pm

Inner tubes for Dawes Kingpin?

Postby HannahR » 30 Oct 2012, 1:06pm

Hello,

I have a much-loved Dawes Kingpin (non-folding) which is about 30 years old and still had it's original tyres and, maybe, tubes as well (or so it looked - at least the people from whom I bought it told me they never used the bike and it had been sitting in their basement as long as they could remember). The tyres were Michelin 500a Comfort 37-440.

Recently I've been unlucky to get punctures first on the rear wheel, and a month later on the front wheel as well. I decided to buy the new tyres as well as the tubes. For the back wheel, I bought a Raleigh tyre (500a 37-440) and a tube from this place:

http://www.ebay.co.uk/itm/Raleigh-Cycle-White-Wall-Bike-Tyre-500a-37-440-NEW-/110563207030?pt=UK_sportsleisure_cycling_bikeparts_SR&var=&hash=item5f7648ff57

- the tyre is a right size and fitted nicely but the tube was slightly bigger (it was 20" x 1 3/8). I still managed to fit it around the rim and under the tyre, trying to make sure it doesn't fold inside the tyre. One month later, it seems to be ok (here, I'm touching the wood :D ).

Now I need to buy a new tube for the front wheel and am wondering if there are tubes for Dawes Kingpin that can fit exactly as they should... For instance, would Michelin F3 Airstop be a right option? It has "28/37 - 440/451 500x28/37a (500a), 20 1 3/8 + 1 3/4" specification, you can see it here -

http://www.chainreactioncycles.com/Models.aspx?ModelID=20482

I'd greatly appreciate any advice on the subject - or perhaps someone out there knows where one can buy the right size tubes?....

thirdcrank
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Joined: 9 Jan 2007, 2:44pm

Re: Inner tubes for Dawes Kingpin?

Postby thirdcrank » 30 Oct 2012, 1:39pm

I've found St John Street Cycles very good for inner tubes in unusual sizes (ie what a lot of shops regard as unusual.)

Shops specialising in folders / and or recumbents also tend to stock stuff for smaller wheels.

The best manufacturer IMO is Schwalbe who really do try to make all the tyres in all the sizes. They generally offer a choice of valve types as well with their excellent innertubes which they size in groups.. The fact that something is manufactured is no guarantee that you will be able to find it in the UK.

This is the Schwalbe nline catalogue.

http://www.schwalbe.co.uk/_webedit/uplo ... nglish.pdf

Scroll down to P 54 (or take it from me) the tube you want is Schwalbe Group 7A (manufactuered with a choice of valves -see above about availability.)
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This next bit isn't meant top be patronising so ignore it if you knew already.

Good info on tyre sizes here:

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3802

The main points are:

Stick to the ertro sizes.

The big number, which is the wheel size, is critical for fitting. The smaller number indicates the fatness of the tyre.

There is obviously a bit of lattitude with tubes - which is why one size is OK for several sizes - but only so much. 35mm difference in diameter is around 10cms in circumference and I can't see how an innertube would be Ok with both.

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531colin
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Location: North Yorkshire

Re: Inner tubes for Dawes Kingpin?

Postby 531colin » 30 Oct 2012, 2:04pm

http://www.spacycles.co.uk/products.php?plid=m2b0s123p409

Listing 7 series tubes in varieties AV7A.....thats Schraeder valve to us, "American valve" to them
..................SV7....thats Presta valve to us, "Sclaverand valve" to them

I don't know if they will fit any better than the tube you bought previously.......I always put a little air in the tube, just enough to make it 3-dimensional, then put the tube in the tyre and fit the whole lot to the wheel, as in my video on Spa's home page. This gives me a chance to spread out a tube thats a bit big in order to avoid pleats in the tube.....pleats will fail over time.

EDIT....Oh heck....7 and 7A are different tyre size ranges in the catalog TC linked....

Russcoles
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Joined: 6 Nov 2010, 8:09pm
Location: Bristol, UK

Re: Inner tubes for Dawes Kingpin?

Postby Russcoles » 30 Oct 2012, 2:17pm

I don't think you can get tubes for a 500A specifically, I believe that the inner tubes on my bike with 451 wheels stated that they were suitable for 500A so any tube for a 20x 1 3/8 tyre should be fine.
It might be worth considering converting to 451 rims at some point, these will be very slightly larger than a 500A and will give you slightly more choice of tyres. The other benefit would be improved braking as steel rims are notoriously bad for braking, especially in the wet. I personally converted my Kingpin to 406 sized rims and had braze ons for V brakes added.

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Si
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Re: Inner tubes for Dawes Kingpin?

Postby Si » 30 Oct 2012, 2:49pm

I just chuck the nearest that I can find in...no probs. Currently have a brommie 16" one in my 20" folder, bit of a stretch to get it in the cover but works fine once inflated.

It's a story that I've related before but it's surprising how much a tube will expand - my club, many years ago, had a competition to see how big a 700c/28" tube would expand when blown up not in a tyre. They bottled out and let the air out when it had got to a state where ten men could stand inside it!

thirdcrank
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Joined: 9 Jan 2007, 2:44pm

Re: Inner tubes for Dawes Kingpin?

Postby thirdcrank » 30 Oct 2012, 3:25pm

A quick search should reveal examples of people who have folded long tubes to get them into a smaller tyre.

Whether Schwalbe are being over-cautious, I don't know, but the info is there for anybody who chooses to read it. You can't decide to ignore something you don't know exists. I always start from the premise that anybody posing a question of this type has nagging doubts about what somebody in a shop has told them, often based on what's in stock rather than what might be best. Something that will "do" in an emergency etc isn't necessarily right if somebody has their wallet out and wants what's best.

As I so often point out, distance cycling is largely a matter of what's going on in the rider's head. Wondering if the innertubes are OK shouldn't be an extra worry.
==============================================
An earlier thread with some info

viewtopic.php?f=1&t=47085&p=388360

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Inner tubes for Dawes Kingpin?

Postby Brucey » 30 Oct 2012, 3:55pm

the michelin tube linked to by the OP will work fine. Not that I would fit one with a pleat or overlap and expect it to be fine for ever, but inner tubes are stretchy, so you don't have to.

BTW it helps if you use a lot of talc, and round out the tube before installation as Colin suggests.

cheers
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