Tube size - does it affect tyre feel?

andy73

andy73

Likes Bikes and Dirt
Okay. so I'm running Schwalbe MTB tubes in my Minion 2.5's but I'm finding I have to run a lot of pressure to avoid punctures and just rims hitting rocks etc.
the tubes are 1.5 to 2.5.

My question is this. If I run a larger tube (say 2.2 - 2.7) will it feel different? ie, can I run the tube at lower pressure as there's more volume?
 
MARKL

MARKL

Eats Squid
My thoughts. Theoretical answer no, practical answer yes. If you run a smaller tube, say 1.5, it will have to stretch much more to fill the volume of a 2.5 tyre compared to the proper sized tube. As a result it will be more likely to pinch flat at similar pressures compared to the larger size tube. Therefore practical solution is to run more pressure to avoid flats...which will affect the feel
 
CresoDH

CresoDH

Likes Dirt
I tried using xc tubes to save a bit of weight ,just gave me headaches from so many pinch flats ,now iam on maxxixs freeride tubes no dramas 1 flat in 50 runs.Just use DH ones or similar, only difference i could feel was on a flater track my legs had to work a bit more to keep speed.
 
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S

sedifus

Likes Dirt
I'd say it will change the feel, but whether you notice it i can't say.

On my bike i run standard 26*1.75-1.90 tubes and have not had any problems. I've pinch-flatted once with put a solid ding in my wheel and blew the tire off, i can't imagine a slightly wider tube will have done anything different. So long as your tires are 2 ply and haven't been worn out or ridden while flat (great way to destroy your sidewalls) you shouldn't have any problems. I have a friend who ran Michelin Latex tubes that were so thin the air escaped and they had to be pumped every day of riding, he didn't have pinch flat issues but i wouldn't bother with them myself

I'd say the thinner tubes will stretch more and allow the tire to conform to the surface of the trail better providing more grip and better bump sensitivity, however marginal. This will also occur in corners and you may feel the tire flexing under heavy cornering.

There's also the weight penalty. According to StarBike Maxxis DH tubes weigh 448g and your standard 1.9-2.125" tube (Chen Shin make most of these) is 205g. I don't know how reliable these weights are but double the weight will definitely affect the rotational mass of your wheel and this slows both your braking and acceleration. I had a look and the ENVE carbon DH rims weigh 475g claimed and an MTX 33 is claimed at 660g. I know it's not everything but to save just under 200g in your rims will be a price difference of around $800 or in your tubes it will be maybe $5 cheaper to save this weight.
 
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andy73

andy73

Likes Bikes and Dirt
Yeah I know there's more weight etc with a dh tube. They're going to e 1.2mm as opposed to .9mm. May point is more around the size. I'm working from the theory that a smaller tube must be harder to fill the tire as it doesn't have sufficient volume to do so at a lower pressure.
 
indica

indica

Serial flasher
Interesting. I used to always get pinch flats riding at Maldon, dh tubes, xc tubes, 35 psi, whatever.
Bought the Fury, did not pump the tyre up ever, checked it eventually after several pings and it was down to 20 psi. Back up to 30 psi, pings but no pinches.
The AM bike runs shitty small volume tubes and pinches a lot in similar terrain - now FNQ. I wonder does that come down to tyre or tube?
Methinks the only way to know would be to test it yourself on a track you know well.
 
D

driftking

Wheel size expert
It deffinately changes the feel.
I have run a 2.25 in my 2.5 tires and even with the same pressure it seemed to have more support with a proper sized tube. It didn't affect my riding though I just pumped some more pressure in,
 
S

sedifus

Likes Dirt
andy73 said:
Yeah I know there's more weight etc with a dh tube. They're going to e 1.2mm as opposed to .9mm. May point is more around the size. I'm working from the theory that a smaller tube must be harder to fill the tire as it doesn't have sufficient volume to do so at a lower pressure.
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I'd say probably a little bit, but once they conform to the tire it will be negligable. The casing on any good tire shouldn't stretch much and this will be providing the maximum volume, rather than the tube limiting it. Maybe a pound difference but that just means pump it up that pound. If they are both to the riding pressure (by feel) you like i can't see there being any differences. It may be harder to fill up but then you just fill it up slightly more to get the same pressure on the tire casing and thus the ground.

It's sort of hard to explain.
 
T-Rex

T-Rex

Template denier
A few comments:

- Volume is determined by tyre size, not tube size. A tube has no reinforcing, so just keeps expanding to fill the inside of the tyre.

- You will get less punctures with a softer rim compared to a harder rim. In terms of reducing pinch flats, changing rims has a more noticable effect than changing tube thickness.

- Using talcum powder on your tubes and inside your tyre reduces friction between the two, and consequently reduces pinch flats.

- you can feel a difference between tubeless and tubes, but thicker or thinner tubes..... maybe the acceleration of the bike feels better? A full DH tube is 400g, and a 200g "trail" tube works just as well, but weighs half as much.

- For the ultimate in preventing pinch flats, nothing beats smooth riding.
 
H

horsey

Likes Dirt
T-Rex said:
Mmmm... dunno about that.

I've got a rack full of UHT Minions with holes in them from pinch flats. For sure tubeless are better than tubes for avoiding punctures, but definately not infallable.
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Agreed. I also went through about 4 minion UST tyres in a couple of weeks with tears through the centre tread. Until some good DH tyre options are available in UST I will stick with tubes.

I've heard all 2013 Schwalbe DH tyres will be tubeless ready...
 
D

driftking

Wheel size expert
T-Rex said:
Mmmm... dunno about that.

I've got a rack full of UHT Minions with holes in them from pinch flats. For sure tubeless are better than tubes for avoiding punctures, but definately not infallable.
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I actually remember you mentioning this in another thread.
Have to do a good job to get through a tire though.
 
P

Philip Bartlett

Squid
the rubber in a tube has a limit to how much it can stretch before it tears, much like a baloon. if you are using tubes that are much too small filling the tyre will put them closer to this point, making it theoretically easier to puncture the tube. thats the science behind it anyway.

the latex tubes mentioned leak not because they are thin (they are actually a relatively thick tube for their weight, I envisioned them being like a franga for your wheel, lol, pulled them out and they are thick like a dh tube) but because latex is not completely air tight, the air seeps through the latex. reason whey they are claimed to reduce punctures, is because they stretch so well (Ithink their marketing BS says they stretch 7X better than butyl) and are not at the point where they will tear if they get pierced by some thing sharp. pinch flat resistance is really along the same lines but without the piercing object, instead view the area of tube being squashed between the rim and tyre as being stretched out very thin (to the point of tearing).

My latex tubes havent had a puncture yet, 4 months in. im sold on them. but thats in more of a AM application, however my next tubes in my DH bike will be latex, to see how they go.
 
K

Kramer

FoBR
If you are running tubes, you gotta talc the insides of your tyres and tubes! I find I get way less pinch flats, and I am sure I also have a lower rolling resistance (due to decreased friction between tube and tyre). I always seem to be rolling up on people without pedalling :-D
 
Loudvq

Loudvq

Likes Dirt
Kramer said:
If you are running tubes, you gotta talc the insides of your tyres and tubes! I find I get way less pinch flats, and I am sure I also have a lower rolling resistance (due to decreased friction between tube and tyre). I always seem to be rolling up on people without pedalling :-D
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That there is the key with tubes! I used to swear by the powder and after the last couple of years I had a break and lately since I have started riding again I haven't been bothered with putting powder in and all I have been getting is flats so it's back to the powder for me!
 
G

Genius Josh

Likes Dirt
Very interesting I run tubeless now but used to talc to keep the tube spread evenly. I found that you would get A mot
Re even (round tyre) with a bit of talc. Inflate deflate reinflate.
 
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