Tyre sizes... Help!

[Jeags]

Hi all,

I've always enjoyed cycling when I had the chance, but never really took it seriously/dedicated myself to it properly. So, I am looking to get into road cycling and luckily (I think), a family friend has an older road bike he said I could have which would help me decide whether I'd want to pursue this further. I will say, that although it is a road bike, I haven't a clue of brands/specs yet, but this will be more to get me on the road and to see whether this develops into a hobby before I look at buying a road bike. The first hurdle I have is that the tyres on them are "Michelin Road Sprint" tyres and are 27x7/8. Although the tyres haven't done many miles, and were new when fitted, they are quite old I believe. I think I need some innertubes for them, however it seems that that size is uncommon now. Can anyone suggest an innertube size that will work with these if possible? If not, then I think I'll need suggestions on tyres as well!

p.s. There are some other numbers on the tyre which are as follows:

10.3
23-630

I think the latter is an ISO number, but any ideas on the 10.3?

Thanks,

Joe

 

[IanSmithCSE]

Good evening

SJS Cycles are a good bet for non race bikes bits, they are the local bike shop that you probably wish yours's were. :-)

https://www.sjscycles.co.uk/tyres-27-630/

Given that they sell the tyres they can probably help with the inner tubes, if they can't then you are in for a hard time finding anyone who can. :-)

Bye

Ian

 

[Pale Rider]

All tyres, including ones for bikes, have a recommended life irrespective of wear.

That's usually about five years, although plenty of cyclists will tell you they are still happily trundling around on tyres which are much older.

Given that you don't know how the bike has been used or stored, the safest course of action would be to set off with new tyres - and tubes.

Sourcing tyres may need some digging, but tubes should be easier to find.

Bear in mind that Schwalbe sell some tubes which are marked for 26", 27.5", and 29" diameter wheels.

Getting approximately the right width is more critical, but a narrow version of one of those Schwalbe tubes ought to fit.

Your next hurdle is the valve, which is likely presta 'skinny' or Schrader - car type, but could be Woods/Dunlop or some other obscure design, depending on the bike.

 

[MichaelW2]

27" is the old British std for race and sports bikes that was dropped in favour of the continental 700c.
7/8 is about the same as 23mm, quite thin by modern standards.
It is rare to find 27" tyres in anything but 1 1/4" which may exceed the tyres clearance at brakes.

Modern 700c inner will fit in 27" tyres. They come in a variety of thicknesses so pic one where your tyres falls in the middle of the range eg 20-25mm width for 7/8" tyres.

Older style bits can be had from SJS Cycles and Freemans of Norwich.

 

[Cycleops]

More important than the size of the tyres on the bike is the size of the bike itself. If you're using it to gauge whether you want to get back into cycling, too large or small could make it difficult to ride for you.
Perhaps you could let us know the size of the bikes seat tube measured from the middle of the bottom bracket to the top. Also your height and inseam measurement.
A pic of the bike would also be good.

Hello and to the forum.

 

[Ajax Bay]

Agree with all advice above.
First check frame size (crossed with post above)
Replace the tyres: they must be 630 ones. Width will depend on clearance between seat stays and chain stays (rear) and fork blades (front). The current ones are 23mm across: measure and see what you can get on. 1 1/4 inch is 32mm (so 32-630).
622 tubes which are widely available (aka 700c) will suit (and they cover width ranges eg 20-25, 25-32). Go narrow with tubes: they are easier to fit.
Spa Cycles have some 25mm wide Panaracers: https://www.spacycles.co.uk/m14b0s121p4427/PANARACER-Pasela-PT-Wired

 

[Jeags]

Thanks for all the advice so far, will have a good look tomorrow. Cheers!

 

[SkipdiverJohn]

Before we get too carried away, are we talking conventional wire bead clincher tyres here or are they tubulars on sprint rims? The 7/8" width suggests they were racing-oriented. If they are tubs, then the OP will have to decide whether to get new tubs and tolerate the issues they have with punctures or replace both the rims and tyres.
i would seriously suggest the OP posts up some pictures of the tyres and wheels and details of the bike showing what the frame clearances are like.

 

[raleighnut]

Before we get too carried away, are we talking conventional wire bead clincher tyres here or are they tubulars on sprint rims? The 7/8" width suggests they were racing-oriented. If they are tubs, then the OP will have to decide whether to get new tubs and tolerate the issues they have with punctures or replace both the rims and tyres.
i would seriously suggest the OP posts up some pictures of the tyres and wheels and details of the bike showing what the frame clearances are like.

7/8ths was the racing standard wired bead tyre, I ve got one on the front of my Carlton (I wore through the back one.

Pretty sure you can still get 1" tyres but 7/8ths are rare and will probably be NOS.

https://www.sjscycles.co.uk/images/products/small/45623.jpg

 

[Gravity Aided]

Sometimes, depending on the brakes, which can always be replaced, you can take a bicycle from 27" tires to 700c without much in the way of modification. I have done this man times. Americans did not make the transition to the 700c until the 1980s in any large numbers.

 

[SkipdiverJohn]

Americans did not make the transition to the 700c until the 1980s in any large numbers.

The good old US of A still likes it's imperial measures even today.
In the UK, the racing fraternity seemed to adopt the 700c size more enthusiastically. There were still plenty of touring and other non-racing bikes being built with 27" wheels well into the 1980's. My Raleigh Royal still has 27's rather than 700's and that was built in 1985!

 

[Gravity Aided]

I can still get 27" tires over here, but the readily available ones are quite heavy.

 

[SkipdiverJohn]

I prefer heavy duty tyres. You get to spend more time riding on them rather than fixing endless punctures. Schwalbe HS159 tanwalls are decent enough 27's Not as tough as Marathons, but not flimsy either and they look more vintage when fitted to lugged steel frames.

 

[Ajax Bay]

the tyres on them are "Michelin Road Sprint" tyres and are 27x7/8. Although the tyres haven't done many miles, and were new when fitted, they are quite old I believe. I think I need some innertubes for them, however it seems that that size is uncommon now.

are we talking conventional wire bead clincher tyres here or are they tubulars on sprint rims? The 7/8" width suggests they were racing-oriented. If they are tubs

Sheldon:
"Back in the 1970s, 622 mm clinchers were very rare in the U.S., and most sporty bikes used either 630 mm (27 inch) clinchers, or standard (622 mm) tubulars. The fact that these sizes are so close led to an in-accurate habit of referring to "27 inch" tubulars. This careless nomenclature still causes confusion, and people often imagine that there is a different "27 inch" size in tubulars as there is in clinchers. This is not true. THERE IS ACTUALLY NO SUCH THING AS A "27 INCH" TUBULAR [Sheldon's capitalising]. All full-size tubulars fit all full-size tubular rims."
I think we can be sure that the "Michelin Road Sprint tyres 27x7/8 " on the bike are clinchers and the advice of other contributors above is useful and worth 'carrying away'.
'Heavy duty tyres' on heavy duty bikes. Road tyres on bikes designed for narrow tyres. Skippy: what do you reckon your puncture/miles figure is, averaged over the last 5 years, say? More/less than 1/3000?

 

[SkipdiverJohn]

what do you reckon your puncture/miles figure is, averaged over the last 5 years, say? More/less than 1/3000?

On the unprotected tyres I use, my puncture rate is significantly worse than that, possibly by a factor of ten. The good Schwalbes have been 100% puncture resistant so far. But then I ride on some really shite surfaces in poor condition and littered with sharp debris. If I used the sort of light road tyres a lot of people on here seem to favour they would get cut to bits long before they ever wore out. My idea of enjoyable cycling does not include carrying out unplanned repairs at the roadside, hence durability is always my overriding criteria.