Hey everybody. I finally decided to put a 29" tube into my 36er. I pumped it up to 20psi last night and it was still intact this morning. 
I then pumped it up to 30psi and so far it’s still intact. 
I want to pump it up to 45psi tomorrow before taking it for a ride, so I’m hoping it doesn’t blow out on me. 
Has anybody done this and used 45psi or higher ??
It seems that putting a smaller tube in a larger tire has been done many times with no ill effects other then a little more care needed when installing to not pinch a tube. You should be good to go.
Here is a past thread:
Jim
Thanks Jim
My real concern is how much pressure I can put in.
I’ve read some posts before on this subject but I don’t remember anybody putting 45psi + in a 29" tube in a 36er tyre. I think it will be ok but I would feel more confident if I knew somebody had done it already. 
Pressure shouldn’t matter. The tyre holds the pressure, not the tube. All the tube has to do is not leak by being stretched too thin, pinched etc.
Stretching shouldn’t be a concern because the tyre doesn’t increase in volume very much once it has enough air in it to hold shape. Pinching the tube between the tyre and rim is the main thing to look out for.
Thanks lightbulbjim What you say makes sense
It hasn.t blown with 30 psi so if there was a pinch I’m thinking it would have been apparent by now. I will pump it up to 45psi and leave it overnight to see if it holds.
I will use my other 36er today 
unibokk, I plan to do this myself, and want to hear what tube you will use – there are lots of 29er tubes that claim to be super-light.
Which very light tubes are people recently and successfully putting into 36ers?
Thanks!
Hello newob.
I have fitted a Continental tube It’s called a Conti tube MTB 29
It’s designed to fit 28/2 x 1.7 > 28/29 x 2.5"
( 47 - 622 > 62-622 )
It has a Presta valve.
I dunno about very light tubes 
But I’m hoping it will work out better than the Foss 36" tube. Its a very tight fit which makes it difficult to get the tyre on.
It might help if you pre stretch the tube by fitting it onto the wheel and leaving it for 24 hours before attempting to fit the tyre on.
Here’s a great video tutorial on how to fit a tyre.
Michelin butyl schrader valve 170gm dont remember the exact specs .
No issue with 45-50psi
Hi,
I ran 29" tubes in my 36er mountain bike for years with no issues.
I found 36" tubes a bit heavy and pain to fit compared to 29" tubes.
@ UniDreamer
@ Fat D
Thanks for the feedback.
I pumped it up to 40 psi this morning and took it for a test ride on a nice long coastal cycle lane, in the wind and rain.
At first I didn’t notice any difference in performance. My main concern was that I had fitted the tube properly without pinching it (the tube was a very tight fit on the rim when I was fitting it on)
I was expecting a loud bang at any moment as I rode 
.
However there was no bang and the ride became progressively more comfortable. I began to notice a real difference in performance. The wheel felt less sluggish and I felt less tired.
I cycled for about fifteen miles and felt really fresh after it. So a big thumb’s up for the 29" tube… :D:D
Hey! Fat D I’d love to see a photo of your 36" mountain bike. I bet It looks impressive.
P.S. Did anybody look at the video I posted in my last post??
Hi Unibokk,
If nobody minds, I’ll post up a photo of my 36er here?
It was a fun machine. The first in Europe. I built the frame, forks and wheels.
The only issue, was the number of questions you would would get when you went out on it. It was nonstop.
Same for me (3.5 bar = 50 PSI), I have been riding 29 or 700cc tubes since I got my 36, 8.5 years ago and rode probably > 5000km with it
I reckon it should be ok to post your 36er mountain bike on here. There’s been many photos of penny farthings on this site . Your 36er mountain bike is a unique bike just like them.
Morning Unibokk,
As requested, a couple of photos of my 36er mountain bike.
The good lady standing next to it before paint.
Finished and out on a test ride.
A short film of it being ridden. I’d just finished it and couldn’t resist a ride. Brakes etc, were fitted later.
Rims and tyres came from the guys at Unicycle.com in the UK
FANTASTIC
A 36er bike with a gear system. The frame looks perfect. It’s a beauty. Well done Fat D. Thanks for posting the photos.
Thanks Unibokk.
I ran round for years with 29" tubes in it. It covered a lot of miles and no issues. My mate in Holland has it now, and as far as I know, he’s still using 29" tubes.
I use the same tubes, for my 29er bikes and 32". For the 32", I use between 40-45 psi, never higher than that. Above that, I consistently blow out tubes.
Thanks Mosca.
Yep, 40-45 sounds good to me. I wouldn’t go higher even with a 36" tube.
I’m very happy with 40psi combined 145 cranks.
