Gravel tyres

[Phototext]

I have an Orbea Gain which has Mavic Aksium Elite UST wheels 622x19 TC-road. I want to fit Marathon Plus Tour tyres 700c x 35 and use my Slime tubes that show 28/32. Will this work? How low can I make the tyre pressure?

Thanks for your help guys.

[Chris Jeggo]

That rim should have an internal width of 19mm - you can check this. A 19mm rim is good for tyre widths of 30 - 39mm. Optimum tyre size is 1.8 times rim width.
A 28/32mm tube will be a bit over-stretched in a 35mm tyre but will probably not explode. Your choice whether to risk it.

[tim-b]

How low can I make the tyre pressure?

That'll depend on you, overall weight, etc, but not as low as you could if you went tubeless

[Nearholmer]

If you do take pressure very low on a combination of Marathon Plus and Slime Tubes, you probably won’t suffer puncture problems, but you will get very high rolling resistance, and a far less comfortable ride over rough ground than you would on tubeless.

Why? Because Marathon Plus are very tough, stiff, and unyielding, and slime tubes equally tend to be rather tough and unyielding. You will be riding on balloons with thick, hard skins, whereas decent tubeless tyres have thin, very supple skins.

Marathon Plus don’t have much tread either, so their grip off-road can be fairly poor.

How much that matters to you or not is a personal thing, influenced by where you intend to ride, and to be traded against the down-sides of good tubeless, which are that they can work out a bit expensive, and do need a tiny bit more maintenance (pumping up a bit more often, and sealant top-up every few months). What I will say is that having swapped about between Continental Contact Plus, Schwalbe Marathon Plus, and tubeless, the Marathon Plus are very much my least favourite, and off-road are frankly horrible.

For on-road touring and general use I found the Continental Contact Plus 37-622 to be very good, lower rolling resistance than the Marathon Plus, but equally as puncture resistant, and they coped better with light off-road too. They last for absolutely ages.

[Chris Jeggo]

How low can I make the tyre pressure?

Frank Berto's tyre pressure chart is a good starting point for experimenting.

[Phototext]

Thanks guys. Perhaps I should explain what I'm trying to achieve. Basically comfort. I'm getting old and have some tendonitis so have fitted a riser stem to be more upright. Reducing the jolting would help too. I have a Cube Reaction Hybrid MTB which is way more comfortable than a road bike and surprisingly quick. It's just so heavy, living it over a gate is too much for me. The Gain fits in my car.

I used to get a lot of punctures which has been solved by using slime tubes and high pressures. I currently have Conti Gator 28s which do seem bomb proof but the roads around here are becoming more gravel than tarmac and I ride a lot of gravel roads. It sounds like tubeless would help.

[531colin]

Thanks guys. Perhaps I should explain what I'm trying to achieve. Basically comfort. I'm getting old and have some tendonitis so have fitted a riser stem to be more upright. Reducing the jolting would help too. I have a Cube Reaction Hybrid MTB which is way more comfortable than a road bike and surprisingly quick. It's just so heavy, living it over a gate is too much for me. The Gain fits in my car.

I used to get a lot of punctures which has been solved by using slime tubes and high pressures. I currently have Conti Gator 28s which do seem bomb proof but the roads around here are becoming more gravel than tarmac and I ride a lot of gravel roads. It sounds like tubeless would help.

Riding position and how you distribute your weight between the contact points can influence jolting. What is getting jolted excessively? Bum, hands?
Can you give us a link to the 2 bikes you mention?

[Nearholmer]

I certainly found that tubeless and a fairly flexible saddle (Brooks Cambium) made a significant difference to comfort off-road, and in so doing allowed me to go a bit quicker. The extra grip that comes from running at low pressure is also very useful - I used to get wheel-spin on loose climbs, damp grass etc when using tubed touring tyres.

The other thing to think about if you’re getting a lot of jolting through the bars/hands is your posture, and especially how much weight you’re putting on hands and arms. I ride some horribly bumpy stuff using drop-bars, but am very conscious not to load my hands, so have a short stem, the bar tops set at saddle height, and when it gets rough I ride on the hoods, as weightlessly as I can, and with the loosest grip - the bars can be bouncing about, but I’m barely actually touching them, and my arms are loose. Likewise bum: when things get rough, it’s always a tiny bit clear of the saddle. Basically the only bits of me in solid contact with the bike are my feet.

Last thought for now: if your drop-bar bike is a full-on road bike, with a steep head angle and very narrow bars, it will be a bit more jolty off-road than a bike with “gravel” geometry, so a shallower head-angle and slightly wider bars on a shorter stem.

(I’m saying a lot of the same as Colin is saying)

[Phototext]

I'm taking the load off my hands & shoulders. The Orbea Gain is a carbon road bike but I have now fitted a short riser stem, looks horrible, but gets the weight off my arms. I have a Selle SMP saddle fitted which I highly recommend to anybody older or having willy problems so the bum jolting is no problem. Fatter tyres appear to be the next step.

[Nearholmer]

Oddly, the Selle SMP saddle I found to be a PITA, because it seemed to want you to sit in a very particular place, and none other, whereas I like to be able to shift about, especially to get over the back of the seat on steep downhills.

[Cugel]

To mute the jolts and judders, I'll relate the ladywife's findings. She is a regular cyclist but not that regular, so sensitive in the regions that connect to a bicycle. She spent a lot of time, research and trial getting her comfort on a bike sorted.

1) Fit the largest tubeless tyres with the appropriate tread you can fit in the frame, of a quality including the thin & flexible (but still puncture-protected) sidewalls another poster mentions, The ladywife has two sets of tyres: 30mm Schwalbe G-One speed for the road & 40mm G-One All-rounds for the forest tracks. These are both fast and tough.

2) Carbon handlebars mounted on a high-quality (i.e. it works) suspension stem such as the Redshift, which it what she uses. The carbon bars are very effective at killing high frequency vibration from the likes of gravel-scab and the suspension stem smooths out the bigger bumps and jolts from minor potholes and road/track ridges.

3) A suspension seatpost of the effective kind. The ladywife uses a Redshift, which can be adjusted to suit your body weight; or, rather, the portion of it you put through yer bum. As can their suspension stem (be adjusted to suit the weight you put through your palms).

4) A flexible (not a highly-padded) saddle of a proper width for your sit bones. A saddle that flexes rather than pads will spread and mute the pressure effects that manage to get past the seatpost. It'll move/flex with your nether. Padding just squashes then makes you sore.

She says that these things have absolutely transformed her riding experience. They not only give comfort and less bashing of the palms and nether but also help the bike stick to the road rather than bouncing. If I ride behind as she goes down a fast and curvy rough-surfaced road, I can see how she floats above the bike, which is deflected up and down by the rough road but without punishing the rider or losing contact momentarily.

PS Them things I mention are not cheap! But worth it.

[531colin]

Whereas I am delighted that my learned friend’s good lady is comfortable, everything that he mentions can be achieved by taking your weight on your feet, rather than on your hands and backside.
Set the saddle low enough so you can pedal in contact with the saddle but with no real weight on it. You can always drop your heels or slide back in the saddle for more knee extension if you want maximum power for a short burst.
To take your weigh off your hands, move the saddle back, your centre of mass is much nearer your backside than your handlebars. You hardly need to hold the bars as Nearholmer says.
After most of a lifetime riding Brooks B17 narrow saddles, I have gone over to SMP TRK saddles. Took me a long time to get them set up right, they look a bit like Concord.....

IMG_5662 by 531colin, on Flickr

There is a simple bike set-up guide linked below.

[Cugel]

Whereas I am delighted that my learned friend’s good lady is comfortable, everything that he mentions can be achieved by taking your weight on your feet, rather than on your hands and backside.

So ..... are you saying that you use only your legs for the suspension effects? Surely riding like this for miles is going to be very tiring - rather like honking the whole way on a ride .....? And to truly avoid kicks and bucks from the bars and seat, won't you have to let go of those bars and never sit down? I'm afraid I couldn't ride like that. Can anyone?

I confess - I can't really grasp what you're suggesting. Perhaps its joke?

[Nearholmer]

Legs are meant to take our weight; that’s how we walk.

More seriously, how I do it is:

Power on, ground a bit bumpy - the effort of pedalling creates a reaction force that keeps the backside floating ever so slightly, so not in rock hard contact with the saddle.

Coasting, ground a bit bumpy - pedals at 12 and 6, weight supported on the 6 o’clock leg, very slightly bent, so again bum not in hard contact with saddle.

Coasting, very bumpy ground - pedals at 3 and 9, weight spread evenly between legs, bum a fair distance above saddle (I can also do “power on” in this crouching, but well above the saddle posture, but only for short lengths of time).

None of those is like honking (which term I only heard since joining this forum), because the centre of mass is kept back, rather than being put forward over the bars.

I think I really only sit down fully on the saddle when the ground is very benign, a road surface or a nice smooth path or whatever.

[531colin]

Whereas I am delighted that my learned friend’s good lady is comfortable, everything that he mentions can be achieved by taking your weight on your feet, rather than on your hands and backside.

So ..... are you saying that you use only your legs for the suspension effects? Surely riding like this for miles is going to be very tiring - rather like honking the whole way on a ride .....? And to truly avoid kicks and bucks from the bars and seat, won't you have to let go of those bars and never sit down? I'm afraid I couldn't ride like that. Can anyone?

I confess - I can't really grasp what you're suggesting. Perhaps its joke?

Yes, what Nearholmer said.....

No joke. Perhaps you should try it? The technique is to distribute your weight between the contact points.
I ride tracks and roads. I think you ride exclusively tarred roads? Are you saying you are constantly kicked and bucked by saddle and bars while riding tarred roads?
Set the saddle low enough so you can get the pedal past bottom centre without sitting your weight on the saddle or honking with no saddle contact,
Almost all the time I have some weight on the saddle, but I don't just sit on it unresponsive like a dead weight, or a sack of spuds. Over rocks and tree roots on tracks its necessary to have very little weight on the saddle, but I prefer to be in contact with the saddle. On roads its relatively infrequently necessary to completely un-weight the saddle, or the bars.
I think we have had a conversation previously where you related "having your hands jolted off the bars" by bumps in (tarred?) roads, and I repeat that this has never happened to me in about 65 years cycling. I set my saddle far enough back that I am in balance with my weight on the pedals, so I don't need to put a significant amount of weight on either the saddle or the bars.