V Brake Booster

Hake said:

Hello,

I am in the final stages of putting our newly refurbished tandem together. I
am trying to improve the braking response at the back (V-brake, fItted with
a V-dapter - to increase cable travel for non v levers). I have a couple of
questions,

Would the QBP Travel agent work better than the v-dapter? (which seems to
add squish due to the tight puley that the cable has to navigate).

What does the a 'V-Brake Booster' actually do? - the retailer says it
increases braking power - my question is how, and would it help me reduce
squish &/or improve return. (i am looking at.
http://www.chainreactioncycles.com/Models.aspx?ModelID=8215 )

Any other hints? I have replaced the cable outer (shimano, low friction
inner) and routed it carefully.

Thanks in advance

Colin

The adapters increase the amount of cable pull. They are required when you use a brake lever that has correct cable pull for standard cantilever brakes.
Another way to deal with the issue is to change brake levers for ones that pull sufficient cable for the brakes you intend to use.... or go back to standard cantilever brakes to match you current lever (which you may not want to change the lever as it is part of a brake/shift lever like STI).
Your title made me think of another part of the overall solution: the booster that you have a link to will help reduce the flex in the seatstays when the brake pads are pushing up against the rim. These things help either kind of cantilever brake.

"Hake" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Hello,

I am in the final stages of putting our newly refurbished tandem together.

I

Quoted message said:

am trying to improve the braking response at the back (V-brake, fItted

with

Quoted message said:

a V-dapter - to increase cable travel for non v levers). I have a couple

of

Quoted message said:

questions,

Would the QBP Travel agent work better than the v-dapter? (which seems to
add squish due to the tight puley that the cable has to navigate).

What does the a 'V-Brake Booster' actually do? - the retailer says it
increases braking power - my question is how, and would it help me reduce
squish &/or improve return. (i am looking at.
http://www.chainreactioncycles.com/Models.aspx?ModelID=8215 )

Any other hints? I have replaced the cable outer (shimano, low friction
inner) and routed it carefully.

Thanks in advance

Colin

Hi Colin,

As per your brake booster question; as daveornee says, they secure the
bosses in place which tend to flex outwards when the brake is applied. The
booster adds extra rigidity to the seat stays/forks.
I too am looking in to getting a booster, for my mtb, i've come across these
on ebay, they look like a deal but i'm undecided at the moment, it may be
worth a look. I can't say how they might perform but they look fairly
substantial i guess (can anyone comment on the quality of these??) :

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ih=017&sspagename=STRK%3AMEW
A%3AIT&viewitem=&item=270085349438&rd=1&rd=1

Good luck.

K

Hi Colin,

Hake said:

What does the a 'V-Brake Booster' actually do? - the retailer says it
increases braking power - my question is how, and would it help me reduce
squish &/or improve return.

As I understand it, the brake booster is meant to reduce flex in the
frame, fork and calipers, particularly when you are braking hard. It
would improve brake pad/rim contact and therefore result in better
braking -- not a bad idea for a tandem, but also not addressing your
particular problem.

Basically, your brakes are squishy because you have a long cable run
to the back. I don't know if there is any real way around this, other
than reducing friction as much as possible, which you have already
done.

As far as return goes, I suggest a couple of things:
1. Tighten both adjustment screws to the limit, and then back only one
off until your brakes are centered. This will give you the most spring
power possible.
2. If your brake studs have three holes, you might try using a
different hole that will put more spring onto the brakes. Not sure
about this, as the extra holes are for cantis. Linear pulls are always
set up in the middle hole.
3. Look into replacing the springs with a stronger one.

Regards,
Anthony

"Anthony DeLorenzo" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Hi Colin,

Hake said:

What does the a 'V-Brake Booster' actually do? - the retailer says it
increases braking power - my question is how, and would it help me reduce
squish &/or improve return.

As I understand it, the brake booster is meant to reduce flex in the
frame, fork and calipers, particularly when you are braking hard. It
would improve brake pad/rim contact and therefore result in better
braking -- not a bad idea for a tandem, but also not addressing your
particular problem.

Basically, your brakes are squishy because you have a long cable run
to the back. I don't know if there is any real way around this, other
than reducing friction as much as possible, which you have already
done.

As far as return goes, I suggest a couple of things:
1. Tighten both adjustment screws to the limit, and then back only one
off until your brakes are centered. This will give you the most spring
power possible.
2. If your brake studs have three holes, you might try using a
different hole that will put more spring onto the brakes. Not sure
about this, as the extra holes are for cantis. Linear pulls are always
set up in the middle hole.
3. Look into replacing the springs with a stronger one.

Regards,
Anthony

Thanks for the advice, I didnt think much of the booster idea at first, but
I have looked more closely at the braking action & can see some flex in the
frame & callipers - I shall give one a try & see if it helps.

Id love to go hydraulic, but I want to tour & dont fancy the extra
spares......and initial spending!!

Thanks again,

Colin

Hake said:

I am in the final stages of putting our newly refurbished tandem together. I
am trying to improve the braking response at the back (V-brake, fItted with
a V-dapter - to increase cable travel for non v levers). I have a couple of
questions,

Would the QBP Travel agent work better than the v-dapter? (which seems to
add squish due to the tight puley that the cable has to navigate).

What does the a 'V-Brake Booster' actually do? - the retailer says it
increases braking power - my question is how, and would it help me reduce
squish &/or improve return. (i am looking at.
http://www.chainreactioncycles.com/Models.aspx?ModelID=8215 )

Any other hints? I have replaced the cable outer (shimano, low friction
inner) and routed it carefully.

Using a pulley-widget to change the cable travel is a very indirect
way to apply brakes (as you've noticed). If it were my bike, what I'd
do:

1) Get a pair of short-arm linear brakes (Tektro made an excellent set
of these, and still make similar ones for BMX use - they're very
inexpensive, but work MUCH better with road levers without using a
travel adaptor of any type).
2) Put POCs (Plain Old Cantis) on the bike (assuming you have the
cable stop, or can mount one). You'll want to spend some time at
www.sheldonbrown.com to work out the set-up, but the ones I had on my
old Santana worked well (particularly after I went to a set of solid
straddles). If you go this way, don't use the fixed-length straddle,
but get the wide straddle that uses a single cable to connect both
canti arms - that'll increase the leverage a bit.
3) Probably not an option, but on the off-chance your twofer has a
brake bridge actually set up for a side-pull caliper, find a side-pull
caliper. The braking on my own Habanero tandem is SO much better this
way that I can't imagine going back to cantis or linear brakes.

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

Magura hydraulic rim brakes HS11
All your problems will be solved!!

SW

Quoted message said:

Any other hints? I have replaced the cable outer (shimano, low friction
inner) and routed it carefully.

Thanks in advance

Colin