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Wide-posts and V-brakes?

Old 03-25-21, 09:53 PM
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RubeRad
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Wide-posts and V-brakes?

So the next problem with the rockhopper is trying to get some V-brakes on there. Turns out, the posts are spaced 9cm, vs the other bike I have with working V-brakes they're 8cm. So with the wide-spaced posts, the arms of the V-brakes have to be squeezed together extra far to get the pads to hit the rims, and there's no room for the boot. I wouldn't care about just tossing the boots, but it just seems wrong, and I bet I couldn't get the pads square, and couldn't get good braking leverage.

What kind of brakes came stock with a rockhopper like this? What brakes can I put on it that will work well?

NOTE this picture shows cantis, they are not stock, they were a first try, now I'm trying V-brakes


Last edited by RubeRad; 03-26-21 at 09:06 AM.
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Old 03-25-21, 10:04 PM
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Cantilever brakes?

John
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Old 03-25-21, 10:09 PM
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Aren't those cantis on it? Those are what came with that era of mtb's.
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Old 03-25-21, 10:12 PM
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Those are cantilever brakes on the bike in the photo, did you remove them and put v-brakes on the bike?
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Old 03-25-21, 10:39 PM
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Your brakes should have washers that you can relocate to move the pads closer to the rim.
I built a skinny "road" wheel for my hybrid and had a similar problem. You may need to find a couple extra washers out of the spare parts bin to add.


Last edited by Bill Kapaun; 03-25-21 at 10:49 PM.
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Old 03-25-21, 10:52 PM
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What does your wheel collection look like? Find a wheelset with wider rims. Rhyno Lites, maybe?

That's the fun part about rebuilding old bikes. Everything on a bicycle works together so, when you change one part, you often find that you have to change something else to make it work.
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Old 03-26-21, 09:09 AM
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Originally Posted by 70sSanO View Post
Cantilever brakes?
Originally Posted by 2cam16 View Post
Aren't those cantis on it? Those are what came with that era of mtb's.
Originally Posted by cobba View Post
Those are cantilever brakes on the bike in the photo, did you remove them and put v-brakes on the bike?
Sorry for the confusion, that pic is from a while back, it shows cantis, but those are out and I'm trying V-brakes
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Old 03-26-21, 09:11 AM
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Originally Posted by Bill Kapaun View Post
Your brakes should have washers that you can relocate to move the pads closer to the rim.
I built a skinny "road" wheel for my hybrid and had a similar problem. You may need to find a couple extra washers out of the spare parts bin to add.
I'll give that a try, I took a brief look and it didn't seem obvious that the pads that are there could just be rearranged, or if I stuck 5mm of spacers in each side to make up the 1cm extra width, that the pads would still be able to be bolted on.

Do they sell extra-long-post replacement pads? (akin I guess to extra-long-reach caliper brakes for reaching 700C wheels from frames built for 27" wheels?)
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Old 03-26-21, 09:12 AM
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Originally Posted by Retro Grouch View Post
What does your wheel collection look like? Find a wheelset with wider rims. Rhyno Lites, maybe?

That's the fun part about rebuilding old bikes. Everything on a bicycle works together so, when you change one part, you often find that you have to change something else to make it work.
Wheel collection does not have any more rear 26" with a freehub. And these rims don't seem particularly narrow. Indeed, the other bike I checked with V-brakes (posts 8cm apart) has narrower rims
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Old 03-26-21, 09:32 AM
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Originally Posted by RubeRad View Post
Sorry for the confusion, that pic is from a while back, it shows cantis, but those are out and I'm trying V-brakes
Are you using v-brake levers with the v-brakes?
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Old 03-26-21, 09:41 AM
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I'm not sure, I think not, but I'm aware I'll need to deal with that, but first off I need to get the v-brake geometry right
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Old 03-26-21, 09:42 AM
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Is there a standard spacing for v/canti brake posts? Does 9cm make v-brakes impossible?
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Old 03-26-21, 12:41 PM
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Originally Posted by RubeRad View Post
I'll give that a try, I took a brief look and it didn't seem obvious that the pads that are there could just be rearranged, or if I stuck 5mm of spacers in each side to make up the 1cm extra width, that the pads would still be able to be bolted on.

Do they sell extra-long-post replacement pads? (akin I guess to extra-long-reach caliper brakes for reaching 700C wheels from frames built for 27" wheels?)
You may only have room for 3-4mm and have to wing it from there.
I don't have quite as much purchase on the threads as I'd like, but close.
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Old 03-26-21, 12:47 PM
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Velocity Cliffhanger rims are 30mm wide outer (25mm inner). Get new rims and you won't need special brake pads.
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Old 03-26-21, 01:06 PM
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yeah, I'm not going to be relacing wheels for this bike
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Old 03-26-21, 01:50 PM
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You generally don't need to change or add any washers to make V brakes work on differently spaced posts or rims - each V brake pad come with two convex washers and two concave washers, one thin and one thick. THe convex washers are always directly against the brake arm so they form a ball, and the thick/thin concave washers can be placed on the inside/outside or outside/inside, respectively, depending on your spacing requirements. There is also a flat washer on most sets and you can put this directly against the pad or under the nut, again depending on spacing requirements - against the pad will give you maximum extension for widely spaced posts.
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Old 03-26-21, 02:32 PM
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You will never get it to work with cantilever brake levers. They will not move the brakes enough to make up the difference unless they are setup with about 1mm gap between the rim and brake pad.

It is the perfect storm wide posts and short pull levers. All you need now is a 7 speed cassette and 9 speed triggers to complete the project.

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Old 03-26-21, 02:58 PM
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well the 7-speed cassette is on there already

I just checked on ebay for 9-speed triggers, but found a great deal on 14-speed triggers, Imma get those and just click twice per gear

Before the brake levers even come into play though, I need to be able to manually/directly work the brake arms so that the pads contact the rims. Right now that happens with about 3cm of cable between the tops of the arms. Small enough to significantly compress the boot in the resting position, which I've never seen before.

I'll post a pic tonight if I can remember.

At least I headed off "those are cantis not v-brakes in the picture you dumbass" within only half a dozen posts

Last edited by RubeRad; 03-26-21 at 03:03 PM.
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Old 03-26-21, 03:02 PM
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Originally Posted by ClydeClydeson View Post
You generally don't need to change or add any washers to make V brakes work on differently spaced posts or rims - each V brake pad come with two convex washers and two concave washers, one thin and one thick. THe convex washers are always directly against the brake arm so they form a ball, and the thick/thin concave washers can be placed on the inside/outside or outside/inside, respectively, depending on your spacing requirements. There is also a flat washer on most sets and you can put this directly against the pad or under the nut, again depending on spacing requirements - against the pad will give you maximum extension for widely spaced posts.
I'll look into that more closely, thx. Maybe if I just bought replacement pads I could sort it out like you say.
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Old 03-26-21, 04:14 PM
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Why no pics of the problem???

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Old 03-26-21, 04:19 PM
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patience, grasshopper

I'll post a pic tonight
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Old 03-26-21, 05:31 PM
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My 97 Hardrock GX came with cantis, still have the bike, brakes are awesome.
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Old 03-26-21, 06:46 PM
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I gotta work on the centering, but this is where the brake cable would need to be set to get the pads reasonably close to the rim.



In this astoundingly-focused picture, you can see my nipple. You can also probably tell that there is a sizable washer stack available for rearrangement. Probably that will do the trick.

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Old 03-26-21, 06:47 PM
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Thx Bill Kapaun, I think you were first to what is probably the right answer, try rearranging washers.

Once again I'm guilty of not looking close enough / thinking hard enough before posting.

I can gare-on-frickin-tea it won't be the last time...
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Old 03-26-21, 06:57 PM
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Originally Posted by RubeRad View Post
Is there a standard spacing for v/canti brake posts? Does 9cm make v-brakes impossible?
Post width for V brakes are normally spec'd at 77-85mm.

Shimano's frame specs are a good example of what is normal.
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