700c for 27" on a Touring Bike

"ethan" <[email protected]> wrote:

>I just replaced the dead 27 inches on a 70's Raleigh Grand Prix with
>700c wheels, but I'm curious whether or not I can do the same on a late
>80's Trek 520 I'm eyeing. Because it uses center-pull mountain-style
>breaks I am not confident I can adjust the height of the brake pads the
>way I could on those old Weinmans.

There's 8mm of difference between the two wheels, meaning that there's
4mm difference on each side of the axle. If you have room to move
your brake pads down more than 4mm (1/6") then you should be able to
use the 700c wheel in your Trek.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

In article <[email protected]>,
Mark Hickey <[email protected]> wrote:

> "ethan" <[email protected]> wrote:
>
> >I just replaced the dead 27 inches on a 70's Raleigh Grand Prix with
> >700c wheels, but I'm curious whether or not I can do the same on a late
> >80's Trek 520 I'm eyeing. Because it uses center-pull mountain-style
> >breaks I am not confident I can adjust the height of the brake pads the
> >way I could on those old Weinmans.
>
> There's 8mm of difference between the two wheels, meaning that there's
> 4mm difference on each side of the axle. If you have room to move
> your brake pads down more than 4mm (1/6") then you should be able to
> use the 700c wheel in your Trek.

In practice, I believe this can be achieved fairly often on bikes with
caliper brakes (using long-reach brakes, drop bolts or a few other
tricks), but it is rarely possible to do with cantis. Maybe there's some
magical unknown special-purpose canti brake set that lets you do this.

There are two common solutions:

1) get a frame builder to move the canti posts. You'll have to repaint,
at least around the canti posts.

2) live with it. Unless you're trying to do cyclocross with the bike
(and maybe even then), there's an acceptable selection of 27" tires and
wheels. I've thought about this with m own 80s tourer (Miyata 210), and
decided to just keep buying 27" tires from my LBS ($10 ea) until I die,
at which point I suspect the inheritor of the bike will be able to
continue buying 27" tires, possibly only by mail order, for another
lifetime or so.

By then, widespread nanofabrication should mean that the tires will be
made on demand (and to custom design if desired) by the bike collector's
universal assembler, located where the microwave oven used to be.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

I've got an early 80's Centurion Pro Tour 15 with canti's and
average 27"s. I would like to put my 700c's on because they are
much better wheels (Campy and Rigida) so I've been poking around this
as well. Moving the posts is out because this frame is chromed under
the paint and I don't want to mess that up. I have adjusted the pads
but there is a bit of an angle now. Not bad but not totally satisfied.
I have seen canti's on new bikes that are slotted. Maybe they would
give me the adjustment needed. I have yet to confirm if the newer
canti's would work.

Steve



Ryan Cousineau wrote:
> In article <[email protected]>,
> Mark Hickey <[email protected]> wrote:
>
> > "ethan" <[email protected]> wrote:
> >
> > >I just replaced the dead 27 inches on a 70's Raleigh Grand Prix with
> > >700c wheels, but I'm curious whether or not I can do the same on a late
> > >80's Trek 520 I'm eyeing. Because it uses center-pull mountain-style
> > >breaks I am not confident I can adjust the height of the brake pads the
> > >way I could on those old Weinmans.
> >
> > There's 8mm of difference between the two wheels, meaning that there's
> > 4mm difference on each side of the axle. If you have room to move
> > your brake pads down more than 4mm (1/6") then you should be able to
> > use the 700c wheel in your Trek.
>
> In practice, I believe this can be achieved fairly often on bikes with
> caliper brakes (using long-reach brakes, drop bolts or a few other
> tricks), but it is rarely possible to do with cantis. Maybe there's some
> magical unknown special-purpose canti brake set that lets you do this.
>
> There are two common solutions:
>
> 1) get a frame builder to move the canti posts. You'll have to repaint,
> at least around the canti posts.
>
> 2) live with it. Unless you're trying to do cyclocross with the bike
> (and maybe even then), there's an acceptable selection of 27" tires and
> wheels. I've thought about this with m own 80s tourer (Miyata 210), and
> decided to just keep buying 27" tires from my LBS ($10 ea) until I die,
> at which point I suspect the inheritor of the bike will be able to
> continue buying 27" tires, possibly only by mail order, for another
> lifetime or so.
>
> By then, widespread nanofabrication should mean that the tires will be
> made on demand (and to custom design if desired) by the bike collector's
> universal assembler, located where the microwave oven used to be.
>
> --
> Ryan Cousineau [email protected] http://www.wiredcola.com/
> "I don't want kids who are thinking about going into mathematics
> to think that they have to take drugs to succeed." -Paul Erdos

[email protected] wrote:
> I've got an early 80's Centurion Pro Tour 15 with canti's and
> average 27"s. I would like to put my 700c's on because they are
> much better wheels (Campy and Rigida) so I've been poking around this
> as well. Moving the posts is out because this frame is chromed under
> the paint and I don't want to mess that up. I have adjusted the pads
> but there is a bit of an angle now. Not bad but not totally satisfied.
> I have seen canti's on new bikes that are slotted. Maybe they would
> give me the adjustment needed. I have yet to confirm if the newer
> canti's would work.
>
Just a comment. I have the exact same bike and had no problem dropping
700c wheels in there. I didn't have an angle on the brake pads, they
went right in. Maybe slight difference in manufacture accounts for it,
I don't know.

(It's a really nice bike, BTW. I have 9 sp bar-end shifters, original
110 bcd crank with 26-36-44 rings, 13-34 cassette and big 700x38 tires.
The quality steel frameset is a nice basis for a nice riding tourer).

Tom

eyeballing the curved components with your hardwired straight line
geometry history and coming to the correct ballpark conclusion is
unlikely-better to try cardboard templates than imagination. you'll see
why when you do it.

Ryan Cousineau wrote:
> In article <[email protected]>,
> Mark Hickey <[email protected]> wrote:
>
>> "ethan" <[email protected]> wrote:
>>
>>> I just replaced the dead 27 inches on a 70's Raleigh Grand Prix with
>>> 700c wheels, but I'm curious whether or not I can do the same on a late
>>> 80's Trek 520 I'm eyeing. Because it uses center-pull mountain-style
>>> breaks I am not confident I can adjust the height of the brake pads the
>>> way I could on those old Weinmans.
>> There's 8mm of difference between the two wheels, meaning that there's
>> 4mm difference on each side of the axle. If you have room to move
>> your brake pads down more than 4mm (1/6") then you should be able to
>> use the 700c wheel in your Trek.
>
> In practice, I believe this can be achieved fairly often on bikes with
> caliper brakes (using long-reach brakes, drop bolts or a few other
> tricks), but it is rarely possible to do with cantis. Maybe there's some
> magical unknown special-purpose canti brake set that lets you do this.
>
> There are two common solutions:
>
> 1) get a frame builder to move the canti posts. You'll have to repaint,
> at least around the canti posts.
>
> 2) live with it. Unless you're trying to do cyclocross with the bike
> (and maybe even then), there's an acceptable selection of 27" tires and
> wheels. I've thought about this with m own 80s tourer (Miyata 210), and
> decided to just keep buying 27" tires from my LBS ($10 ea) until I die,
> at which point I suspect the inheritor of the bike will be able to
> continue buying 27" tires, possibly only by mail order, for another
> lifetime or so.

Good summary. But there's another solution for the terminally frugal.
Canti brakes generally allow you to adjust the angle of the brake pads.
If you can point the pads down far enough, you can use a 700c wheel. I
have a Fuji touring bike from the 80's set up this way.

If you do this, a line from the rim/brake pad contact point to the brake
pivot may be more than 45° from vertical. That means the brake pad is
sweeping more downward (towards the hub) than horizontal. Here are some
bad points of that arrangement.

­· The mechanical advantage is much higher than usual
· Higher risk of brake pad/sidewall interference
· The brake pad wears at an odd angle
· As the break pad wears, it is more likely to slip past the rim and
into the spokes

To minimize some of these effects, extend the brake pad as far as
possible from the canti. That will help with the mechanical advantage
and odd brake pad wear. But not much. I have flipped my brake pads
upside down so both sides are used, which sorta compensates for the odd
pad wear. This adds to the required maintenance of the bike.

The good thing about switching to 700c wheels is that you'll be able to
fit larger tyres. I can now fit 700x37 tyres with large knobs and ice
studs *and* fenders on the bike in question. And I can swap wheels with
my other bike(s) as necessary.

I think Ryan's suggestions are better than the route I've chosen. I
should probably move the brake pivots on my bike, but I've been too
cheap thus far.

--
Dave
dvt at psu dot edu

"dvt" <[email protected]> wrote in message
news:[email protected]...
> Ryan Cousineau wrote:
> > In article <[email protected]>,
> > Mark Hickey <[email protected]> wrote:
> >
> >> "ethan" <[email protected]> wrote:
> >>
> >>> I just replaced the dead 27 inches on a 70's Raleigh Grand
Prix with
> >>> 700c wheels, but I'm curious whether or not I can do the
same on a late
> >>> 80's Trek 520 I'm eyeing. Because it uses center-pull
mountain-style
> >>> breaks I am not confident I can adjust the height of the
brake pads the
> >>> way I could on those old Weinmans.
> >> There's 8mm of difference between the two wheels, meaning
that there's
> >> 4mm difference on each side of the axle. If you have room
to move
> >> your brake pads down more than 4mm (1/6") then you should be
able to
> >> use the 700c wheel in your Trek.
> >
> > In practice, I believe this can be achieved fairly often on
bikes with
> > caliper brakes (using long-reach brakes, drop bolts or a few
other
> > tricks), but it is rarely possible to do with cantis. Maybe
there's some
> > magical unknown special-purpose canti brake set that lets you
do this.
> >
> > There are two common solutions:
> >
> > 1) get a frame builder to move the canti posts. You'll have
to repaint,
> > at least around the canti posts.
> >
> > 2) live with it. Unless you're trying to do cyclocross with
the bike
> > (and maybe even then), there's an acceptable selection of 27"
tires and
> > wheels. I've thought about this with m own 80s tourer (Miyata
210), and
> > decided to just keep buying 27" tires from my LBS ($10 ea)
until I die,
> > at which point I suspect the inheritor of the bike will be
able to
> > continue buying 27" tires, possibly only by mail order, for
another
> > lifetime or so.
>
> Good summary. But there's another solution for the terminally
frugal.
> Canti brakes generally allow you to adjust the angle of the
brake pads.
> If you can point the pads down far enough, you can use a 700c
wheel. I
> have a Fuji touring bike from the 80's set up this way.
>
> If you do this, a line from the rim/brake pad contact point to
the brake
> pivot may be more than 45° from vertical. That means the brake
pad is
> sweeping more downward (towards the hub) than horizontal. Here
are some
> bad points of that arrangement.
>
> ­· The mechanical advantage is much higher than usual
> · Higher risk of brake pad/sidewall interference
> · The brake pad wears at an odd angle
> · As the break pad wears, it is more likely to slip past the
rim and
> into the spokes
>
> To minimize some of these effects, extend the brake pad as far
as
> possible from the canti. That will help with the mechanical
advantage
> and odd brake pad wear. But not much. I have flipped my brake
pads
> upside down so both sides are used, which sorta compensates for
the odd
> pad wear. This adds to the required maintenance of the bike.
>
> The good thing about switching to 700c wheels is that you'll be
able to
> fit larger tyres. I can now fit 700x37 tyres with large knobs
and ice
> studs *and* fenders on the bike in question. And I can swap
wheels with
> my other bike(s) as necessary.

I have been doing this for 20 years with a Cannondale T1000 that
was sold with 27" wheels. No problem with an old Shimano canit
or the original Scott SE. It was a problem with a Paul NeoRetro
on the front -- it would not work at all. I put on an
after-market cyclocross fork that fixed that -- also went
threadless. The steering is a little different now, but still
plenty rideable. -- Jay Beattie.

ethan wrote:
> I just replaced the dead 27 inches on a 70's Raleigh Grand Prix with
> 700c wheels, but I'm curious whether or not I can do the same on a late
> 80's Trek 520 I'm eyeing. Because it uses center-pull mountain-style
> breaks I am not confident I can adjust the height of the brake pads the
> way I could on those old Weinmans.
>
> Thanks.
>
Tektros seem to have a lot of vertical adjustment -- $15/pair at Nashbar.

I had purchased an old Trek 720 and did the 700c upgrade. The only thing I
discovered was that some Canti brakes fit better than others. I had an old
set of Cannodale Codas that fit, but the Shimano XT fit better and had more
adjustment. Also, because the brakes pads are lower on the calipers, I
tended to need a larger straddle wire than usual. Other than the slightly
longer straddle wire, it worked fine.