27 inch wheels

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stuartg
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27 inch wheels

Post by stuartg »

I have question which I have tried to google without a satisfactory answer!

I have a bike with an old set of 27inches 1 1/4 tyres on I assume a 27 inch wheel. I was planning to change these tyres as I have an newer set of 700c (23) tyres.

From the sites I can't work out whether this is possible. They both run on clinchers. I appreciate that the sizes are slightly different, but is this difference enough to compromise the tyre?

Thanks for your help.

Stuart
PW
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Post by PW »

They won't fit. The wire bead on the tyre has a diameter of 622mm for 700C but 630mm for the old 27". Inner tubes are interchangeable but the tyres definitely aren't. You can usually fit 700C wheels in a 27" frame, but you may or may not need to change the brake calipers depending on how far down the slots go. Sometimes you're lucky, sometimes not, check if the blocks will drop a further 4mm.
If at first you don't succeed - cheat!!
stuartg
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Post by stuartg »

PW thanks for the clarity in the reply - looks like I will put the wheels and tyres back together again. I will check to see if the breaks will drop by a further 4mm.

I will then look for a 700c wheel, this is an area that I know little about :oops: (only had a newer bike previously - it's a restoration project) but can you get 700c wheels that will accept a 6 speed shimano cassette?

Thanks

Stuart
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Mick F
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Post by Mick F »

700c wheels come in just about at 26 and a half. That is about half way between 26 inch and 27 inch. So they certainly won't fit.

As an aside, I'm sorting out my mate's bike. I found out that he's got a 700c on the front and a 27 inch on the rear!

Not only that, he's got a 5sp block when the Shimano SIS lever has clicks for 6sp. Good grief!!!
Mick F. Cornwall
AndyB
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Post by AndyB »

stuartg wrote:can you get 700c wheels that will accept a 6 speed shimano cassette?


I'd guess the 6 speed is on a freewheel, rather than the more modern freehub, so easiest way might be to build a new 700c wheel around the old hub (if it's a decent hub in reasonable condition)? Someone else might be able to point you towards a replacement though...

On the other hand, if you only wanted to change because of the tyres, you can still get new 27" tyres - that would certainly be the simplest option. Spa cycles sell some good quality ones (Schwalbe, Panaracer), and even my LBS had some cheap ones.
stuartg
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Post by stuartg »

I have been on the web and it looks like the tyres are the way to go, been on the St Johns site and they also do a sport continental, which is probably what I am looking for.

Thanks everyone for the advise.

Stuart
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CJ
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Post by CJ »

Mick F wrote:As an aside, I'm sorting out my mate's bike. I found out that he's got a 700c on the front and a 27 inch on the rear!

Admittedly a bit odd, but not a problem really.

Not only that, he's got a 5sp block when the Shimano SIS lever has clicks for 6sp. Good grief!!!

That's not a problem at all. Five and six speeds have the same sprocket spacing, so six speed levers are exactly what you wanted to index 5-speed. I use the past tense only because 5-speed freewheels and 6-speed indexing levers have virtually dropped off the bottom end of the market now. But if his frame and wheel have only enough space for five, it may be best to leave those levers in place.
Chris Juden
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Mick F
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Post by Mick F »

Hi CJ.
The story went on today.

The 27 inch wheel didn't fit very well at all. The wheel was too high, and nearly fouled the rear brake bridge, and unless it was set far enough back in the rear dropouts, would foul the chainstay bridge.

When I found out that his Raleigh Team (remember the yellow ones from the 1980s?) was supposed to be 6sp rear, I also found out that the 6sp SIS didn't click far enough (despite what you say) for each of the 5sp spacing on this strange rear wheel that he'd put on. As it turned out, he'd got the wheel off a very old Sun he'd got in a shed! I dug around in my old spares box and found my Suntour Ultra stuff. I put together a 13 - 28 freewheel cluster, and screwed it on. (If you remember, the 6sp took up about the space as an old 5sp.)

Lo and behold, the SIS downtube lever shifted exactly all six speeds, well not exactly as the whole system is quite worn, but it worked very well. He rode away on it this evening.
Mick F. Cornwall
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Post by PW »

Sounds like you're talking about a compact 6 freewheel. They had the same cog spacing as a standard 7 so the 6 sprockets went into the same width as the old 5. Rare as rocking horse sh1t these days but I think there's one on the Claud Butler tandem hung up in my shed.
If at first you don't succeed - cheat!!
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Mick F
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Post by Mick F »

Yes, the Suntour Ultra was compact. They may be rare, but I've got a tinful of the bits! Actually one body and six sprockets less now!

Ron Kitchen used to stock them, and a shop in Paignton (an hour away from here). I used to spend hours working out ratios and deciding on which sprocket for when! A pair of home-made chain whips, and a ratio change would take five minutes.
Mick F. Cornwall
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CJ
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Post by CJ »

If the 5-speed freewheel was not indexed correctly by the 6-speed shifter this may have been because the mech was not compatible with the shifter, or the freewheel did not have the standard 5/6-speed sprocket pitch, or most likely because one or several components were worn and/or gummed up with dirt. The point I'm making is that all being well, such a combination is correct and ought to work, so Mick's exclamation: "Good Grief!!!" is unjustified.

Such a comment might more appropriately be applied to the system Mick has subsequently assembled, but which nevertheless works well enough. Such mis-matched systems often will work after a fashion. If the shifter is worn that might actually help, plus the fact the sprocket pitch on a SunTour Ultra freewheel isn't truly consistent with any standard spacing. It works nevertheless and that's always a good thing, irrespective of whether it comes about by good judgement or good luck.
Chris Juden
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Mick F
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Post by Mick F »

More luck than judgement then eh? CJ! Thanks yet again for sage advice and info!

Any road up, he went away happy as a sand boy! (and I used up some of my old stuff!)

Regards,
Mick F. Cornwall
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