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Old February 4th 19, 08:12 PM posted to rec.bicycles.tech
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Default Wider tires, All-road bikes

On Sunday, February 3, 2019 at 5:07:55 PM UTC-8, Roger Merriman wrote:
wrote:
On Saturday, February 2, 2019 at 12:47:07 PM UTC-8, Roger Merriman wrote:
wrote:
On Thursday, January 31, 2019 at 5:07:40 PM UTC-8, Roger Merriman wrote:
wrote:
On Wednesday, January 30, 2019 at 7:27:08 PM UTC-8, James wrote:
On 31/1/19 5:02 am, wrote:
On Tuesday, January 29, 2019 at 2:59:39 PM UTC-8, James wrote:
On 30/1/19 6:13 am,
wrote:
On Tuesday, January 29, 2019 at 6:07:16 AM UTC-8, Roger Merriman
wrote:


You’d think it would be so, but really quite differing brakes
don’t seem to cause confusion. I will admit that first time I
use the MTB with is 180mm etc disks they are so instant, but
actually you don’t lock, it’s a very easy system to use to it’s
full, ie tyres at the point of locking but not quite etc.


If you're applying the disk brakes and hit a bump it is WAY too
easy to lock the brakes up.


Disk brakes are normally associated with better brake modulation
than rim brakes. That means with disk brakes you can achieve more
brake effort without locking a wheel. You seem to be contradicting
that.

-- JS

Not really. A full suspension MTB has a different center of gravity
and weighs twice what a road or cross bike does. When you have 2"
wide tires and a great deal of weight disks do modulate much better
because you can retain traction most of the time.

Whether the bike weighs 10 kg or 20 kg does not change much when the
rider weighs 80 - 90kg.

The biggest difference is that a full suspension MTB will retain tyre
contact with the road or track surface better - however, as you start to
brake the suspension forks should compress which starts to rotate you
over the bars, which is bad.

There are two problems with a xcross bike - it weighs very little - a
32 mm cross knobbie can easily have so much traction that the bike
can rotate around it's much high center of gravity. And on hard
surfaces you can lock the brakes very easily since there is less
traction.

Regardless of bike weight, if you're going to brake hard you must move
your body backwards as much as possible, to prevent the rear wheel from
lifting. Even motorcycle riders who do defensive riding courses learn this.

My gravel bike comes standard with 42mm tyres. It can handle slightly
wider. Not dissimilar to many MTB tyres.


With road bikes they reduced the size of the disks dramatically. The
reason that they even went to disks was to not wear out expensive
carbon rims. So instead they wear out easily and cheaply replaceable
metal disks. Using Campy skeleton brakes I can easily lock the brakes
if I wish to. So what would I gain using disks other than cheaper
replacement costs?

Smaller disks on road bikes is because there is significantly less tyre
on the road - but it should still be possible to lock the front brake
and send yourself over the bars, especially if you don't move your body
backwards.


I am not anti-disk brakes but there are horses for courses. If you
are building a superlight bike with superlight components why would
you put an very un-aerodynamic and heavy disk brake systems on it?

3 months of riding my Colnago with carbon wheels show less wear that
a single month on aluminum wheels. Though I have to replace the
basalt brake pads all the time.


It facilitates easier CF rim use, and doesn't require rim brakes to have
a quick release so the brake pads can be moved out of the way of wide
tyres. You know the pros use 27 - 28 mm tyres for cobbled classics?
They won't get past properly adjusted rim brakes without a quick release.

--
JS

I don't think we agree on this: I weigh 84 kg and a 20 kg bike most
assuredly climbs slower than snot on a cold day. With my cross bikes I
would come up behind a FS 29er and try to pace him because I don't like
blowing by people as if I were better than they. But eventually I just
can't go that slow and have to pass. Though I try to do it mildly
until I'm out of sight.

I will say that really rough, steep climbs that you have to carry a cross
bike up these long wheelbase MTB's can carry such a low gear that they
can climb almost anything.

I have 28's on my Time VX Elite with an Ultegra group on it and the brake
releases work fine. Let's remember that today's disk brake bikes have 10
mm one piece axles and so there is no such thing as a quick release.. Plus
you have to thread the wheel between the forks plus carefully insert the
disk through the brake pads without knocking them off.

That's why most of the road racing teams are not using disks


Unless they are E-MTB or possibly downhill a full suspension 29er will not
be 20kg, mine which is at best mid pack, is 12/13kg I’d agree that
cross/gravel bikes tend to climb shallower smoother climbs such as fire
roads faster, sometimes by quite a bit equally once it gets steeper and
rougher the MTB will shine.

What race mechanics may not find difficult shouldn’t really be a pressing
problem unless your a race mechanic, if your riding with a support car,
where wheel change speed matters then possibly something to consider..

Roger Meriman

I had a Gary Fisher HiFi 29er which was just before he sold out to Trek
who made the Trek HiFi. That bike was too heavy to weigh as I recall
since I hang my scale from an overhead nail in a shelf. But my estimate
with the seat pack and water bottle would easily be 20 kg. At the time
this was the very top of the line.


Looking that bike up they are (just) sub 12kg, a water bottle generally 1/2
a kg full, unless your bike packing a seat pack isn’t going to be, 7kg.

My old commute MTB with panniers and a bar bag is 20kg as it has locks and
what not, but the FS MTB is closer to the gravel bike, you can get very
light MTB not quite as light as roadie but remarkably close.

Roger Merriman


I ALWAYS carry a seatpack and have never been sorry that I do. That would
make the bike around 15 kg, There are a lot of full suspension bikes on
the trails around here and I have passed plenty of them and NEVER been
passed by one except downhill while I was riding my cross bikes.

Sure you can get a FS bike pretty near my cross bike weight for a mere $10,000.

I’d be surprised if your saddle pack, was over 1kg, even with inner tubes
these things are all quite light, catching MTB on a CX/gravel bike on fire
roads and what not is fairly easy, and weight doesn’t seem to be the big
thing, my first CX/gravel bike was really very cheap and heavy, was
dangerously close to my MTB in weight, but could still leave MTBs for dead
up such climbs, the newer and a fair bit lighter/better Gravel bike there
really isn’t much in it if the gradient is mild, such as most fire roads
and what not.

By the time folks add water bottles and what not the difference between
road and MTB narrows.

Roger Merriman


It is slightly less than one KG and a water bottle half that. So the Ridley XBow weighs 23.6 lbs without the bag or bottle. That makes it at LEAST 26.6 lbs or 12 kg. What full suspension bikes weight anywhere near that figure? And the Ridley is a couple of lbs heavier than the Redline.
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