Tektro CR720 w/Marks Rack Conflicting

[Garth]

When installing some CR720's today on the Bombadil, I found out they
conflict big time with a Marks front rack, mounted at the braze-ons
below the canti bosses. This is not good. When installed, the brakes
cannot open to get the tire out, they hit the struts of the Nitto. Is
this a secret that I was not aware of?

What to do? I don't know.

[Robert F. Harrison]

I think the recommended rack for cantilever brakes is the Mini-Front which is very like the Mark's except for the stays and other attachments. I've got the Mini-Front and CR720 on my QB.

From Riv...

Mark's:
Our own Mark Abele came up with this design, and Nitto executed it perfectly. Basically, we wanted a rack that could be used on the front of a bike with sidepull brakes

Mini-Front:
When your bike has cantilevers or V-brakes and you just need a smallish rack up there for a bag or basket or stuff-sack, this is the best choice. Even Mark, of Mark's Rack fame, uses it on his bike with cantilever brakes.

The stays are bent on the Mini-Front to work around the cantis:

http://www.rivbike.com/images/products/full/0000/0871/20-020-1.jpg

And not on the Mark's

http://www.rivbike.com/images/products/full/0000/0874/20-108-2.jpg

Though it does look like the stays on the Mark's are separate pieces, unlike the mini-front, so perhaps longer ones could be used to bend around the cantis.

Other than that, no clue.

Aloha.

Bob

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[Aaron Young]

I couldn't get the Mark's Rack to work on the front of my bike with the CR720 cantis either.  I ended up putting it on the rear and it fits just fine (although it is a bit short compared to most rear racks).

Aaron Young

Rochester, NY

On Fri, Aug 6, 2010 at 7:31 PM, Ginz <the...@gmail.com> wrote:

Yeah, that sounds like one of those incompatibilities you only come
across through personal experience.  You could try some lower-profile
brakes or the Nitto M12 rack.

[Garth]

Thanks for that Bob and Aaron.

It seems my choice is a new rack or some extra long struts mounted to
the mid low braze-ons instead of below the canti's. Riv is out of the
long struts though.

Or in the back. I already tried that, though I preferred it up front.

I guess I can mount the Nitto 2 strut rack in the front either.
Gheese. My best laid planes have gone to h-e double toothpicks
multiple times with this bike.

So much for plans!

[Garth]

Really though ...... this is the third brake I've tried using on the
Bombadil. I was hoping to use one paired set. Right now I have a mixed
set of vintage Shimano canti's on there. The canti bosses are
irregular in depth, so some brakes bind when tightened on the rear.
Darn quirks. Sigh .....

I would like to use the CR720's , as I waited a long time for
polished silver ones. They've upgraded their pads to 55mm road/cross
sized and nice holders, not the 72mm pin type they had. Pads and
holders are # 720.12 http://www.tektro.com/02products/pads.php

[Angus]

Garth,

Without pictures I may be visualizing this incorrectly...but, (as
Robert pointed out) can you bend the lower stays in a manner similar
to the mini-front rack to allow the cantilevers to open wider?

Part of the fun & frustration of assembling a unique bicycle is making
everything work together. If it were easy, everyone would do it!

Angus

[Garth]

On Aug 7, 7:17 am, Angus <angusle...@sbcglobal.net> wrote:
> Garth,
>
> Without pictures I may be visualizing this incorrectly...but, (as
> Robert pointed out) can you bend the lower stays in a manner similar
> to the mini-front rack to allow the cantilevers to open wider?
>
> Part of the fun & frustration of assembling a unique bicycle is making
> everything work together.  If it were easy, everyone would do it!
>
> Angus

Yes ..... it's like a jigsaw puzzle!

I though of bending the struts, but at room temperature I don't think
they are that bendable. If they were heated however ..... I bet they'd
bend to shape easily. I have zero experience with a torch though, and
the struts would need to be longer than they are. If I get longer
ones ,I may as well mount them mid low on the those braze-ons.



I do ponder an open question though , if Mark's rack was not intended
for canti's, why does the Bombadil have the threaded holes on top of
the fork for it? These work perfectly for that rack. I guess the
answer is it works with *some* cantilevers, but not the super wide
ones like Frogglegs or CR720. The vintage wide BR-MC70 I have on there
now in the front fits fine because the triangle sticks out higher than
on the CR720, as seen here. http://www.flickr.com/photos/11316881@N04/4860392084/
..... The BR-MC70 was taken from another bike to fit he Bombadil, as
my Plan 1 was to use XC Pro canti's, but their low profile had meager
stopping power on this frame due to it's large clearances, the yoke
angles were poor. The rear brake is a well used Shimano BR-MT62 I
found on ebay , as the BR-MC70 didn't work there as it binded on the
canti post. These were meant to be temporary brakes until I could find
some new ones.... but they may need to stay permanently.

[rperks]

somewhere on youtube is a video of Mark at riv bending them with a
hammer and vise, you do not need to heat them, just do it like you
mean it. The vise holds them at the same time and orientation for a
syncronised bend. Call riv and talk to mark or one of the guys for
moral support, they may even have a bent and cut set to solve this, as
they sell the bike rack and model of brakes.

Rob

On Aug 7, 5:43 am, Garth <garth...@gmail.com> wrote:
> On Aug 7, 7:17 am, Angus <angusle...@sbcglobal.net> wrote:
>
> > Garth,
>
> > Without pictures I may be visualizing this incorrectly...but, (as
> > Robert pointed out) can you bend the lower stays in a manner similar
> > to the mini-front rack to allow the cantilevers to open wider?
>
> > Part of the fun & frustration of assembling a unique bicycle is making
> > everything work together.  If it were easy, everyone would do it!
>
> > Angus
>
>   Yes ..... it's like a jigsaw puzzle!
>
> I though of bending the struts, but at room temperature I don't think
> they are that bendable. If they were heated however ..... I bet they'd
> bend to shape easily. I have zero experience with a torch though, and
> the struts would need to be longer than they are.  If I get longer
> ones ,I may as well mount them mid low on the those braze-ons.
>
> I do ponder an open question though , if Mark's rack was not intended
> for canti's, why does the Bombadil have the threaded holes on top of
> the fork for it? These work perfectly for that rack.  I guess the
> answer is it works with *some* cantilevers, but not the super wide
> ones like Frogglegs or CR720. The vintage wide BR-MC70 I have on there
> now in the front fits fine because the triangle sticks out higher than

> on the CR720, as seen here.http://www.flickr.com/photos/11316881@N04/4860392084/

[J. Burkhalter]

here's the link to Mark bending struts

http://www.youtube.com/watch?v=65yQS1AuAfc

-Jay

[Garth]

Hey guys, thanks for the help. After a ride to clear my head and
watching the video, I reconfigured and lowered the rack, with a little
bending of the struts, and everything just fits!

I do have one more question though, regarding the pad holders hitting
the fork blades the front , which is new to me as I've always used
small enough pads that they never hit the fork blades.

What do you do if you have wider tires than you have clearance between
the pads? I have 50.5mm there on the Bombadil. I have a set of
Michelin 2" tires that I may use in the future. Just squeeze it
through?

Anyone using larger than 2" tires on a Bombadil or Atlantis must have
come across this.

[Garth]

After getting the CR720 on the front, I notice they I have to put the
hanger quite a bit off center for it to pull evenly. The spring adjust
screws help a little ,but not enough. My previous brakes had no spring
adjustment and the pull was dead straight.

Any ideas would be appreciated.

[Angus]

To add a radius to the bend you can bend them over a dowel/wood broom
handle. I do it in the vise ala the video except with a dowel in
there too.

I don't think it would be a problem in this case, but aluminum doesn't
like sharp corners too much.

Angus

[Thomas Lynn Skean]

on a Bombadil it may be less of an issue, but...

I put a couple layers of the Lizard Skin protective stickers on the
inside of the fork bladed where the pad-holders hit them when the
brakes are fully open. I've got a wet-paint Hillborne; maybe your
Bombadil is powdercoated, which might not really need the protection.
Anyway, I got a Lizard Skin clear chainstay protector and cut from it
patches that did *not* have any logo on them to do this.

Oh, and I imagine you'd deflate the tire to get it past the brakes if
there's no room otherwise even when the brakes are open. At least, I'd
do that instead of discombobulating my brake pads; deflating/inflating
a tire is less tedious than re-adjusting brakes.

Yours,
Thomas Lynn Skean

[Garth]

Thanks for bending tips Angus, they're really helpful.

Thomas .... your idea has me thinking ..... I'm going to try cutting
some strips of clear chainstay protector and put those inside the fork
blades where it hits. My paint is Dupont Imron, so it does chip and
all , sometimes easier than one would like. But, all my bikes are
missing paint all over the place so I really shouldn't worry about it.
I'm a sucker for Imron metallic paints!

[Garth]

I've used these brakes for a few rides now. They work well, but they
shed brake material like I've never seen. My rims are coated with
black brake dust from 2 rides. These pads won't last long.

I think I'll try some SwissStop Black pads or VO's squeal free ones.
Anyone use either?

[William]

When I thought about a Mark's rack on the front of my Bombadil,
Rivendell recommended against it (Dave). Dave told me to only use the
Marks Rack if I absolutely have to. If you can use the Mini front, on
any bike, absolutely that rack wins, he said.

Those lower struts are load bearing. On the Mini front, they are
bent, but they are also tubular steel. Bend the Marks Rack aluminum
struts and they will be much weaker than if they stayed straight. On
the Mini Front, the joints are welded, not bolted together, also much
stronger. If it's just going to be a handlebar support it might be
fine. If it's going to get a platrack bolted to it with 25lbs of
stuff, or a big wald basket and a case of beer, I would worry about
the strength if the struts are bent.

Dave told me the top of the fork crown bolts on my Bombadil are
intended to enable me to run a big rear rack on the front, not to run
a Marks Rack.