Spoke Tension per MTB Wheels

P. Lynn Miller said:

Good day to all,

I have reviewed most of the material written on wheelbuilding, but most of
it seems to be geared toward road riding, which is fine. But I have just
started building wheels for MTB racers. So far I have had no complaints. But
just wanted to hear some thoughts on how tight MTB wheels should be laced
given the fact that MTB wheels take a huge amount of abuse.

If you tension as per normal road specs which is close to maximum, are you
building a wheel too close to failure for use off-road taking hits from
logs, jumps, and whatever else nature can through at a wheel.

Thank you

Wheels are wheels, regardless of use. Pick the proper rims, use a good
hub(XT), use enough 14/15 spokes, lace 3 cross, and the tension for
right side rear and front should be 100 kgf, measured on a
tensionopmeter.

P. Lynn Miller said:

I have reviewed most of the material written on wheelbuilding, but
most of it seems to be geared toward road riding, which is fine. But
I have just started building wheels for MTB racers. So far I have
had no complaints. But just wanted to hear some thoughts on how
tight MTB wheels should be laced given the fact that MTB wheels take
a huge amount of abuse.

What is it that you think is different whether the load on the wheel
comes from asphalt or dirt? If there were such a difference I would
not so readily ride my thin tired bicycle on unpaved roads and forest
trails.

http://www.paloaltobicycles.com/alps_photos/f64.html

Quoted message said:

If you tension as per normal road specs which is close to maximum,
are you building a wheel too close to failure for use off-road
taking hits from logs, jumps, and whatever else nature can through
at a wheel.

I think you should read ho a bicycle wheel supports loads before
making that assessment. Spokes do not become tighter when riding over
obstacles, the downward spokes in the road contact area slacken. You
can find out about all this in "the Bicycle Wheel" that also has an
extensive section on wheel building.

http://sheldonbrown.com/harris/books.html#brandt

Jobst Brandt

P. Lynn Miller said:

Good day to all,

I have reviewed most of the material written on wheelbuilding, but most of
it seems to be geared toward road riding, which is fine. But I have just
started building wheels for MTB racers. So far I have had no complaints. But
just wanted to hear some thoughts on how tight MTB wheels should be laced
given the fact that MTB wheels take a huge amount of abuse.

excess tension increases the propensity of the rim to taco - contrary to
popular belief, it does not make the wheel "stronger". similarly
insufficient tension can allow spoke nipples to work loose unless
threadlocked.

Quoted message said:

If you tension as per normal road specs which is close to maximum, are you
building a wheel too close to failure for use off-road taking hits from
logs, jumps, and whatever else nature can through at a wheel.

Thank you

simply build according to the rim manufacturer's spoke tension spec. as
peter says, a wheel is just a wheel.

Thanks, Mr. J. Brandt et al

Quoted message said:

What is it that you think is different whether the load on the wheel
comes from asphalt or dirt? If there were such a difference I would
not so readily ride my thin tired bicycle on unpaved roads and forest
trails.

I believe that there is practically no difference in loading or stress on a
wheel that is ridden on asphalt or dirt as you say. But I was not referring
to a wheel being ridden on gravel roads or even fire trails. I am talking
about a wheels that is ridden over 160kms of technical single track during
an 8-hr race, facing a constant on-slaught of tree roots, rocks, logs, ruts
and rough landings from taking air from tired racers. That is how the wheels
I am building are being used. The level of stress and loading is raised to a
whole new level over a wheel that is used on marginally smooth surfaces with
some sort of care.

Quoted message said:

I think you should read ho a bicycle wheel supports loads before
making that assessment. Spokes do not become tighter when riding over
obstacles, the downward spokes in the road contact area slacken. You
can find out about all this in "the Bicycle Wheel" that also has an
extensive section on wheel building.

I understand how a wheel supports loads and have read most everything that
has been written on wheels including your own writings, and as far I can
tell there is as much agreement on the subject as there is on the virgin
birth.

Just was inquiring of the experience of anyone out there that specializes in
building wheels for free-riders, trials and endurance MTB racers.

Thanks,

P. Lynn Miller