700c for 27" on a Touring Bike

ethan said:

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 hidden]>,

Mark Hickey said:

ethan said:

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 hidden] 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 said:

In article <[email hidden]>,

Mark Hickey said:

ethan said:

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 hidden] 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

Quoted message said:

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 said:

In article <[email hidden]>,

Mark Hickey said:

ethan said:

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 hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Ryan Cousineau said:

In article <[email hidden]>,

Mark Hickey said:

"ethan" <[email hidden]> wrote:

> I just replaced the dead 27 inches on a 70's Raleigh Grand

Prix with

Quoted message said:

Quoted message said:

Quoted message said:

> 700c wheels, but I'm curious whether or not I can do the

same on a late

Quoted message said:

Quoted message said:

Quoted message said:

> 80's Trek 520 I'm eyeing. Because it uses center-pull

mountain-style

Quoted message said:

Quoted message said:

Quoted message said:

> breaks I am not confident I can adjust the height of the

brake pads the

Quoted message said:

Quoted message said:

Quoted message said:

> way I could on those old Weinmans.
There's 8mm of difference between the two wheels, meaning

that there's

Quoted message said:

Quoted message said:

Quoted message said:

4mm difference on each side of the axle. If you have room

to move

Quoted message said:

Quoted message said:

Quoted message said:

your brake pads down more than 4mm (1/6"😉 then you should be

able to

Quoted message said:

Quoted message said:

Quoted message said:

use the 700c wheel in your Trek.

In practice, I believe this can be achieved fairly often on

bikes with

Quoted message said:

Quoted message said:

caliper brakes (using long-reach brakes, drop bolts or a few

other

Quoted message said:

Quoted message said:

tricks), but it is rarely possible to do with cantis. Maybe

there's some

Quoted message said:

Quoted message said:

magical unknown special-purpose canti brake set that lets you

do this.

Quoted message said:

Quoted message said:

There are two common solutions:

1) get a frame builder to move the canti posts. You'll have

to repaint,

Quoted message said:

Quoted message said:

at least around the canti posts.

2) live with it. Unless you're trying to do cyclocross with

the bike

Quoted message said:

Quoted message said:

(and maybe even then), there's an acceptable selection of 27"

tires and

Quoted message said:

Quoted message said:

wheels. I've thought about this with m own 80s tourer (Miyata

210), and

Quoted message said:

Quoted message said:

decided to just keep buying 27" tires from my LBS ($10 ea)

until I die,

Quoted message said:

Quoted message said:

at which point I suspect the inheritor of the bike will be

able to

Quoted message said:

Quoted message said:

continue buying 27" tires, possibly only by mail order, for

another

Quoted message said:

Quoted message said:

lifetime or so.

Good summary. But there's another solution for the terminally

frugal.

Quoted message said:

Canti brakes generally allow you to adjust the angle of the

brake pads.

Quoted message said:

If you can point the pads down far enough, you can use a 700c

wheel. I

Quoted message said:

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

Quoted message said:

pivot may be more than 45° from vertical. That means the brake

pad is

Quoted message said:

sweeping more downward (towards the hub) than horizontal. Here

are some

Quoted message said:

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

Quoted message said:

into the spokes

To minimize some of these effects, extend the brake pad as far

as

Quoted message said:

possible from the canti. That will help with the mechanical

advantage

Quoted message said:

and odd brake pad wear. But not much. I have flipped my brake

pads

Quoted message said:

upside down so both sides are used, which sorta compensates for

the odd

Quoted message said:

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

Quoted message said:

fit larger tyres. I can now fit 700x37 tyres with large knobs

and ice

Quoted message said:

studs *and* fenders on the bike in question. And I can swap

wheels with

Quoted message said:

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 said:

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.