Linear recumbent tyre advice

[a.twiddler]

It certainly is, hence resubmitting the same post with editing! No edit button as far as I can see, so I had to re submit it.

[Jdsk]

You can edit your own posts by using the pencil icon.

Jonathan

[a.twiddler]

Useful to know. Thanks for the info.

[Cunobelin]

The beast is now up and running and I have had a longer ride or two and am getting to know its peculiarities. The Vittoria Randonneur is nominally a 700 X 42C but the actual width is 38mm. Nevertheless it has supple sidewalls and rolls well. I am experimenting with tyre pressures at the moment.

The front tyre is the original Michelin Diabolo and now it is cleaned up it doesn't look too bad. The previous owner stated that it is a 451 and indeed it has 20 X 13/8 marked on it which seems to be right. However, while checking tyre pressures today I found that it also had 37-440 (500A Confort) marked on it which would seem to contradict the imperial markings. Every reference I have found so far states that a 20 X 1/38 corresponds to a 451 rim size so I am a bit baffled. More so, as I already have a 20 X 11/8 Durano waiting to go on once I have to replace it. On the plus side, the current Michelin does look like it will last a while, but even so.... does this come under the category of "Strange French sizes"? I don't feel inclined to take the front wheel off and mess around with tyres at present though that might ultimately the only definitive way to find what fits. Might even have to get the drum brake rebuilt into a 406 rim eventually. I thought the 451 was limiting enough but something even more obscure? Dearie me.

I hope one of you knowledgeable folks out there can shed some light on this.

(re submitted with editing)

This is a useful link:

https://www.cyclinguk.org/cyclists-libr ... tyre-sizes


I have always found that ignoring the sizing and going for the ISO / Etro numbers is more accurate.

[a.twiddler]

Yes. I know that now! Strange that even on that list the 500A has no imperial size shown against it, while the 451 does, and the previous owner believed that this wheel was a 451, so having seen the equivalent imperial size on the side of the tyre, I was also convinced that it was. I looked
at several tyre size comparisons including the one linked to and Sheldon Brown's before ordering a 451. I have a folder with 406 wheels which are noticeably smaller than the one on the Linear. I had not encountered the 500A size before, so it never crossed my mind that there might be an intermediate size.

looking on the bright side, the tyre on it looks to have more life left in it than I originally thought, and due to the low loading on the front end will not need a high pressure. Max psi on the sidewall is 58, and I will surely need less than that. I will keep an eye out for something in the meantime. Preferably with some puncture protection and a reflective stripe to match the rear! A Schwalbe of some description perhaps. Not keen on the white sidewall, but most of those that I've looked at in the last hour or so have them. This size is not so rare as I initially thought, and generally low priced.
There might be some marginal comfort advantage to having a larger supposedly 20" wheel than the 406. Also, the wheel has a nice drum brake with an alloy rim.

[nigelnightmare]

20x1 3/8" is 438mm so the tyre will be marked 37-438 20 x1 3/8.
That's what mine is.
The rim has 438-19 stamped on it.

HTH

[a.twiddler]

Yet more confusion! So a 20 1 X 13/8 could be a 37 -406, -438, -440, or -451. The 37-438 must be pretty uncommon in this country. It's not on the CUK list but it is on Sheldon Brown's. For a front wheel you could put any used wheel that fits into the fork if it's got what you want on it, eg drum brake, hub dynamo etc (if the brake will reach) so it's not surprising that there is a variety of front wheels on the Linears. After all, it doesn't have to match the rear.

I had assumed that a 451 was the most likely wheel to be found on a USA made bike so finding a French standard wheel size on mine is unexpected. Might have come from a Dawes kingpin or similar? Though it doesn't explain the alloy rim.

[Cunobelin]

Yes. I know that now! Strange that even on that list the 500A has no imperial size shown against it, while the 451 does, and the previous owner believed that this wheel was a 451, so having seen the equivalent imperial size on the side of the tyre, I was also convinced that it was. I looked
at several tyre size comparisons including the one linked to and Sheldon Brown's before ordering a 451. I have a folder with 406 wheels which are noticeably smaller than the one on the Linear. I had not encountered the 500A size before, so it never crossed my mind that there might be an intermediate size.

looking on the bright side, the tyre on it looks to have more life left in it than I originally thought, and due to the low loading on the front end will not need a high pressure. Max psi on the sidewall is 58, and I will surely need less than that. I will keep an eye out for something in the meantime. Preferably with some puncture protection and a reflective stripe to match the rear! A Schwalbe of some description perhaps. Not keen on the white sidewall, but most of those that I've looked at in the last hour or so have them. This size is not so rare as I initially thought, and generally low priced.
There might be some marginal comfort advantage to having a larger supposedly 20" wheel than the 406. Also, the wheel has a nice drum brake with an alloy rim.

The advantage for me was the wider availability of tyres for 40 including studded tyres for winter


The Small Tyre Shop has a wide range of small tyres in a range of sizes

[a.twiddler]

Thanks for the link. I see that there is a choice of 406 and 451, none for 440 at present. I have bookmarked the site for future reference. I can see that there is more choice for 406, and as for speciality tyres, the 406 seems to be the way to go. Also, if you destroyed a tyre on glass or whatever while on tour, a LBS might be more likely to have a 406 to get you going again. As for the present, 37-440 is what I have got and the wheel is decent so I will work with that for now.

[a.twiddler]

As the difference between 438 and 440 on paper at least is just 2mm on the bead diameter are they in real life likely to be interchangeable or am I missing something else here ? I have come across a tyre described as a 500A but the specs show 37-438. This is getting seriously bonkers, and I am finding it dangerous to assume anything now, even though it seems to match what Nigelnightmare said in his earlier post.

[nigelnightmare]

It was precisely that confusion that made me change it to a 451 wheel with hub brake.
I went with 451 as I already had a rim and a couple of' Durano tyres lying around, so all it cost was new spokes.
If I'd had to buy one then I would go for 406 as that seems to be the most popular size with a wide selection of tyres.

Evidently the 438 is a special size for Dutch children's bikes & is Very difficult to source tyres for them as they are no longer used or made.

I too thought of using the 440(500A) size BUT they are getting rare & limited in the tyre sizes/types. Mainly NOS.
Using a 500A tyre on a 438 rim will only result in an extra 2mm diameter which makes them easier to fit but not too loose as to come off.

[a.twiddler]

But would it work the other way, that is 438 tyre on 440 rim? A bit tight to get,on maybe but as there are reports of even matching tyres and rims of some makes being harder or easier to fit than others, I am guessing that it is possible due to manufacturing tolerances. It would be helpful to know if anyone had actually done it, as it might open up a few more choices.

[Tigerbiten]

But would it work the other way, that is 438 tyre on 440 rim? A bit tight to get,on maybe but as there are reports of even matching tyres and rims of some makes being harder or easier to fit than others, I am guessing that it is possible due to manufacturing tolerances. It would be helpful to know if anyone had actually done it, as it might open up a few more choices.

It depends on the internal shape of the rim.
If there's no center well then they may just be hard to fit.
If there's a center well then they'll go on ok but they may not seat fully all the way around and you'll have a flat spot.
My trailer rims are like the second sort, tyres go on easily but I always end up with a flat spot.
To fully seat the tyres takes soap/washing up liquid on both the tyre bead and the rim. Then I need to pump them up to 120%-150% max pressure. Max recommended pressure of 80 psi and I need 100-120 psi to fully seat the tyre. Once they are fully seated all around I can let the pressure down to around 50-60 psi everyday pressure without the tyre moving.

Luck ............

[thirdcrank]

To get a tyre properly seated all round, I've found that it helps to take the weight off it ie lay it down to inflate it, either the whole bike or with the wheel out. Obviously, that's a lot easier with a pump with a connecting hose: floor pump, Topeak Morph etc.

[a.twiddler]

Thanks folks. I think it's worth giving it a shot. I will post here as to how I get on!