Ohhhh many problems hummmm

In message <g2rim1-
[email hidden]>, Simon Brooke
<[email hidden]> writes

Quoted message said:

Well, my Mantra is at last getting there. It's now ridable
enough to get the feel of it, experience its oddnesses,
start to learn what it can
do.

But there are frustrating little problems.

When I acquired the frame it had an Icon chainset on which
although obviously worn looked as if it was just about
still usable for testing. As soon as I'd completed my first
attempt to get the bike together it was obvious that this
was too optimistic - the thing sucked chain like a FIAT
robot that had accidentally wandered into a spaghetti
eating competition. So it had to go. I first tried swapping
on an old Shimano BioPace chainset I had lying around, only
to find that although the taper was the same, on the
Biopace the base of the taper was in the plane of the
middle ring but on the Icon it was in the plane of the
granny ring. Ain't going to fit not nohow. So today I went
out and bought a new Shimano Deore 510 chainset and stuck
it on. It does fit, sort of. Now the base of the taper is
too far inboard, so the front deraileur won't swing far
enough for the chain to reach the big ring. Frustration! So
now presumably I need a bottom bracket with a shorter axle.
Am I right? Does this make sense?

Sounds right. I'd nip it into your LBS and they should be
able to tell you which one you need after a spot of
measuring.

Quoted message said:

Next, the seatpost. The Mantra has an extraordinarily large
diameter seatpost. The one that came with the frame is
missing its seat clamp parts. It's (again) an Icon, a
single bolt type. Because I don't have a vernier caliper I
can't tell the exact diameter of the tube, but being an
unusual size it's going to be expensive to replace. There
wouldn't be some awfully nice person with a single-bolt-
type Icon seatpost they're not using, would there? I
imagine the seat clamp parts will be the same for all
diameters of tube...

Icon were Trek's own brand parts. I think the saddle clamp
parts were the same size between the different diameters,
but it's been a while since I played with any. If you don't
want to buy a high zoot seatpost Kalloy do (or certainly
did) one of their 15 quid wonders in the right size. Any LBS
with a Fishers account should sort you out with one.

Quoted message said:

As it is I've cannibalised a clamp from another make of
tube, but it doesn't fit exactly and the consequence is
every time I go over a big bump my saddle changes
angle. Ouch!

Apart from that the thing is now working, and it's
interesting enough to have made the exercise worthwhile.
The things people say about 'interesting' handling on the
Mantra seem to be partly true. It has the most amazing
brake jack effect. If you sit in the saddle and ride it
like a normal bike it really does try to stand on its head
when braking. The front suspension compresses and the
extremely long travel rear suspension really comes up. On
the other hand, if you shift your [censored] out of the saddle it
doesn't seem nearly such a problem, and I didn't have any
difficulty achieving some pretty impressive emergency stops
down hill.

The other famous Mantra quirk, the bottom bracket moving
about with respect to the saddle, doesn't (so far) bother
me at all. But getting on the bike in the first place is
interesting because with the rear suspension uncompressed
the saddle is amazingly high. I haven't tried riding
anything really severe yet but the bike feels very nice and
I get the feeling I'm going to like it.

I need to overhaul the forks which aren't working properly
yet; I need to sort out the bottom bracket problem and the
seatpost problem; I need to get some SPD pedals, and a new
handlebar would be nice; and then I will have a really
interesting, really classic, quite light full suspension
bike, and so far I've spend under £550. Which is not bad
going at all.

Enjoy it, they certainly are interesting beasts to ride,
they benefit most from a smooth riding style, the suspension
design doesn't respond well to quick jerky movements and
braking, as you're finding out! 🙂

--
Thomas Letherby