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V-brake question/26" to 700c conversion

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V-brake question/26" to 700c conversion

Old 06-21-23, 02:14 PM
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V-brake question/26" to 700c conversion

I am wanting to put 700c wheels on my older Trek 7000fx 26" MB. The wheelset I have fits OK but obviously the brake reach is off. What choices would I have for calipers that would reach? Looks like I need about 35mm longer.
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Old 06-21-23, 02:42 PM
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Short answer is none.

However, It's been a long time since I last considered this so I could be wrong.
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Old 06-21-23, 02:44 PM
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I've seen some v-brakes made for this purpose on AliExpress. Try searching for "v-brake long arm" to see some options. Don't know any recommendations though..
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Old 06-21-23, 03:24 PM
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Originally Posted by louky
I am wanting to put 700c wheels on my older Trek 7000fx 26" MB. The wheelset I have fits OK but obviously the brake reach is off. What choices would I have for calipers that would reach? Looks like I need about 35mm longer.
You may have an easier time finding a decent reach sidepull brakeset to use... is your frame drilled for fenders? is the fork solid or suspension type? here are a couple possible leads for V-brake adapters.. but it doesn't sound very promising or cheap...... Good luck... https://forum.bikeradar.com/discussi...-to-700c-wheel
and here's a link to a similar discussion on MTBR... https://www.mtbr.com/threads/convert...reaks.1018472/

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Old 06-21-23, 04:02 PM
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I would just stick with 26" personally but on some frames, Paul Motolites are a great choice. They won't work with everything but they do have quite a bit of adjustability.
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Old 06-21-23, 04:49 PM
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I gave the short answer earlier. Here's more of an explanation of your problem.

The distance from pivot to rim is a critical dimension. There is some wiggle room provided by the shoe mount slots, but that's it.

Changing that distance changes all the critical brake design properties, including leverage &cable travel needed.

So, even if someone made a brake for this, everything else would be wrong.

If someone made it, what you'd want is something like a horseshoe which mounts on the existing pivots and positions a new pair in the right place.
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Old 06-21-23, 04:59 PM
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Mavic made this adapter years ago for that purpose:



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Old 06-21-23, 06:18 PM
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Originally Posted by FBinNY
I gave the short answer earlier. Here's more of an explanation of your problem.

The distance from pivot to rim is a critical dimension. There is some wiggle room provided by the shoe mount slots, but that's it.

Changing that distance changes all the critical brake design properties, including leverage &cable travel needed.

So, even if someone made a brake for this, everything else would be wrong.

If someone made it, what you'd want is something like a horseshoe which mounts on the existing pivots and positions a new pair in the right place.
I found a video that shows this conversion done two ways. Would the adaptors shown at about 9:30 in the video change the leverage and cable travel or would it just act the same way as it would on the original post location?
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Old 06-21-23, 06:25 PM
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That's a version of the horseshoe I was describing.

For all practical purposes, it's as if the original studs were at the right height.

If they're available at a decent price, go for it.

However, a reminder. These ONLY work if the original studs are removable.


IMPORTANT SIDE ISSUE.

this is a suspension fork. Does the wheel still clear when the fork is FULLY compressed? It's a critical question because if the wheel hits the crown on a hard bump, it'll lock and send you over the bars.

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Old 06-21-23, 06:30 PM
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And I found these on Ebay. This requires that you have removable pivot post (or bosses whatever you call them). There is also the issue of the thread on the M10 bolt that would attach this new piece to the bike would need to match the pitch of the female thread on the bike. I know these bosses come in two thread pitches. This appears to add 22mm to the distance, which just might get me there. Bicycle Bike V Brake Extension Seat Adapter Screw Kit 406 To 451 Conversion Tool | eBay
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Old 06-21-23, 06:44 PM
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Originally Posted by FBinNY
That's a version of the horseshoe I was describing.

For all practical purposes, it's as if the original studs were at the right height.

If they're available at a decent price, go for it.

However, a reminder. These ONLY work if the original studs are removable.


IMPORTANT SIDE ISSUE.

this is a suspension fork. Does the wheel still clear when the fork is FULLY compressed? It's a critical question because if the wheel hits the crown on a hard bump, it'll lock and send you over the bars.
I only looked at this in terms of distance from the wheel to the yoke or whatever it's called but now I see what you mean. Pressing down as hard as I can on the forks leaves me plenty of room. Is there a way to fully compress this to do a check?
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Old 06-21-23, 06:56 PM
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Originally Posted by louky
I only looked at this in terms of distance from the wheel to the yoke or whatever it's called but now I see what you mean. Pressing down as hard as I can on the forks leaves me plenty of room. Is there a way to fully compress this to do a check?
You might see a "high water" mark on the stanchion based on prior use. If so, you can do some comparative measurements. Otherwise, mount the original wheel, wrap pipe cleaner or cable tie around the stanchion, and do so aggressive riding. The fork will push it and leave it as a reference of the travel limit, then do some measurements.
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Old 06-21-23, 11:27 PM
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Originally Posted by louky
And I found these on Ebay. This requires that you have removable pivot post (or bosses whatever you call them). There is also the issue of the thread on the M10 bolt that would attach this new piece to the bike would need to match the pitch of the female thread on the bike. I know these bosses come in two thread pitches. This appears to add 22mm to the distance, which just might get me there. Bicycle Bike V Brake Extension Seat Adapter Screw Kit 406 To 451 Conversion Tool | eBay
I've been curious about those as well but somehow recall reading somewhere that in practice they are quite flexy and don't work super well. Just hearsay, though.
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Old 06-22-23, 03:24 PM
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I worked on this today, to verify that I could get all of the brake bosses out of the frame, prior to ordering the extension seat adaptor mentioned above. The bosses on the bike have an M10 x 1.50 thread so I hope the thread that comes on the attaching bolt is the same.

I also hooked up a ratchet strap and compressed my fork as much as possible to verify the 700c tire doesn't hit when compressed. I will report back when I get these installed.
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