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Question about using disc brake adapters to mount on old suspension fork?

Old 07-02-20, 11:13 AM
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CaptainPlanet
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Question about using disc brake adapters to mount on old suspension fork?

Non-tapered 1 1/8 sr suntour fork, air suspension I think. I have a hard time finding another fork of the same grade with disc brake mounting for cheap and used, and I am looking to see if I could use these disc brake mounting adapters on my old fork. This doesn't look very secure, can I trust these things? It's not even screwed to anything on the fork, it looks like the brake could wobble every time I remove the wheel even if I tighten the ring on top.
And will the adapter fit the fork?

Are there any other adapter I should look into? The fork does have one screw hole at the bottom.

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Old 07-02-20, 11:41 AM
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I wouldn't do it on my bike. With brakes, any doubt makes it a NO-GO for me. You might check out Magura hydraulic rim brakes: https://www.magura.com/en/components/bike/rim-brakes/ My HS-33s are great.
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Old 07-02-20, 11:42 AM
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Originally Posted by CaptainPlanet View Post
Non-tapered 1 1/8 sr suntour fork, air suspension I think. I have a hard time finding another fork of the same grade with disc brake mounting for cheap and used, and I am looking to see if I could use these disc brake mounting adapters on my old fork. This doesn't look very secure, can I trust these things? It's not even screwed to anything on the fork, it looks like the brake could wobble every time I remove the wheel even if I tighten the ring on top.
And will the adapter fit the fork?

Are there any other adapter I should look into? The fork does have one screw hole at the bottom.

I wouldn't.

I have enough trouble keeping my regular discs adjusted between wheel changes, no way these would stay put.

Why not just get some nice sticky salmon pads and some compression-less housing for the v-brakes? Then clean the rims with rubbing alcohol and a scotch Brite pad. That'd stop you.

Magura still makes hydraulic rim brakes if youust have them, but they're worth more than your bike.
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Old 07-02-20, 12:26 PM
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Originally Posted by dsbrantjr View Post
I wouldn't do it on my bike. With brakes, any doubt makes it a NO-GO for me. You might check out Magura hydraulic rim brakes: https://www.magura.com/en/components/bike/rim-brakes/ My HS-33s are great.
Originally Posted by rosefarts View Post
I wouldn't.
I have enough trouble keeping my regular discs adjusted between wheel changes, no way these would stay put.

Why not just get some nice sticky salmon pads and some compression-less housing for the v-brakes? Then clean the rims with rubbing alcohol and a scotch Brite pad. That'd stop you.

Magura still makes hydraulic rim brakes if youust have them, but they're worth more than your bike.

So I guess it's back to search for a branded cheap front shock then. The reason I want disc brake is to prepare for winter weather. With the rim being wet and the tires not gripping the road as well, I want to improve my chances a little bit.
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Old 07-02-20, 01:30 PM
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I would not either. Unless youíre in muddy scenarios and braking is life or death, a solid v-brake and pads are all youíll really need.
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Old 07-02-20, 01:36 PM
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Originally Posted by CaptainPlanet View Post
I have a hard time finding another fork of the same grade with disc brake mounting for cheap.

Would you call $225 shipped brand new cheap? Probably an upgrade from the SR Suntour. I'm assuming 26er. If not, they come in 27.5 and 29 also.

https://www.modernbike.com/product-2...xoCBoYQAvD_BwE
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Old 07-02-20, 01:40 PM
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Oops, looks like they're sold out in a lot of places, some promising more stock mid july, some August. Universal claims to have ONE. I'm always skeptical of just one, but... and they want $250.

https://www.universalcycles.com/shop...s.php?id=90305
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Old 07-02-20, 03:14 PM
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Originally Posted by LesterOfPuppets View Post
Would you call $225 shipped brand new cheap? Probably an upgrade from the SR Suntour. I'm assuming 26er. If not, they come in 27.5 and 29 also.
It's a very nice bike with quality parts, but I can't spend over 100 on a fork when I got the bike for a little over 100 bucks.
I probably have a better chance buying a newer brand name bike with dual disc brakes for 200 if I camp on Craigslist long enough.
It's not super dated because it still has with derailleur hanger and threadless stems, but it came out before disc brakes got mainstream.

Last edited by CaptainPlanet; 07-02-20 at 03:37 PM.
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Old 07-02-20, 03:18 PM
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The other unmentioned reason not to put disc brakes on a dropout/QR fork is that front disc braking torque has
been known to rotate the FW out of the dropout with catastrophic potentiality to ones head/face there. Not for nothing the
devising of through axles for disc wheels where the axles are in a complete circle of enclosing metal.
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Old 07-02-20, 04:59 PM
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Originally Posted by CaptainPlanet View Post
With the rim being wet and the tires not gripping the road as well, I want to improve my chances a little bit.
If your tires don't have any grip the best brakes in the world won't do you any good.
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Old 07-02-20, 07:54 PM
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Say I take out the shock cover piece by itself and try to weld a disc brake mount to it, would it work?

Tires are cheaper and more readily available than the forks. Still in planning phase for all the potential mods and stuff.
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Old 07-02-20, 09:14 PM
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No, the weld won't work.

If you absolutely must have a front disc (forget about rear) then something like this will work. https://www.ebay.com/itm/264088134040

You'll lose suspension but I doubt you'll notice.

Still, you're ignoring the best advice here, get those v-brakes working like a charm. I think you're obsessing over something new when just tuning what you've got is enough.

People have managed to stop in water for the last decade. You don't need discs.

You paid $100 for it, it's not worth much more than that, don't break your budget over it. The original brakes are just fine.
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Old 07-02-20, 10:24 PM
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Originally Posted by rosefarts View Post
No, the weld won't work.

If you absolutely must have a front disc (forget about rear) then something like this will work. https://www.ebay.com/itm/264088134040

You'll lose suspension but I doubt you'll notice.

Still, you're ignoring the best advice here, get those v-brakes working like a charm. I think you're obsessing over something new when just tuning what you've got is enough.

People have managed to stop in water for the last decade. You don't need discs.

You paid $100 for it, it's not worth much more than that, don't break your budget over it. The original brakes are just fine.
I keep wanting to modify it because I really think this is going to be the definitive bike for me with its scratchless frame, almost complete set of Deore 3x8 speed groupset, sr suntour air fork, insanely decent mid rang specs that I have never experienced until now.
I was thinking of buying another okay bike that runs 27.5~29 inch tires and disc brakes but worse groupsets, and then swap the deore groupset onto there and then sell off the 26" bike, but so far I haven't had any luck
So instead I decide to put 27.5 tires (which I found to be compatible) and disc brake (mechanical, just the front) onto there so I can fulfill my vision of what an ultimate bike is like to me and call it a day. All my recent threads on this subforum are about working toward this.

Last edited by CaptainPlanet; 07-02-20 at 10:34 PM.
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Old 07-03-20, 01:32 AM
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The adapters are garbage and welding onto that fork is a good way to go to the ER. Seriously, get some good V brakes with Koolstop salmon pads and get them adjusted well--discs are great but you really don't need them for winter commuting.
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Old 07-03-20, 02:01 AM
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Originally Posted by CaptainPlanet View Post
Say I take out the shock cover piece by itself and try to weld a disc brake mount to it, would it work?.
1) I donít know the alloy
2) I donít know your welding skills

It is possible - in general terms. Iíve done it and lived to tell the tale. Made a fixture to hold stuff in place first. Despite that I got a lateral offset I still DONíT know where it came from which caused some assembly issues. Caliper and rotor were planar and centered though.
If you decide to go this route I suggest you put the caliper on the front of the opposite leg. This eliminates all risk of wheel ejection.
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Old 07-03-20, 05:44 AM
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I wouldnít mess with it. A well set-up canti or v-brake will be better than a bodged-up disk anytime.
Winter weather? Youíre on a bike, not Ice Road Truckers.
Get the orange Kool-stop pads an learn how to set up a brake. V-brakes with fresh pads and straight wheels are stone-simple.
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Old 07-03-20, 09:04 AM
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I have a rigid Miele MTB that I ride al through the winter. I had it with cantilever brakes properly set up but wanted better braking in the snow and slush. I converted it to V-brakes and even without the better stopping ability of KoolStop pads the bike stops when I want it to. The limiting factor for me now is the grip the tires have on the road. I find it quite easy to skid a tire in the snow or slush so disc brakes would NOT be an IMPROVEMENT for ME. YMMV

Oh, that bike has a dropbar handlebar and Tecktro V-brake brake levers.


Cheers
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Old 07-03-20, 09:27 AM
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My foulest weather , Ice & snow bike uses drum brake hub wheels,,, they've been reliable for 35 years..
I retrofitted an old rim brake MTB.. Sturmey Archer company has changed hands during this time frame..

they're still being made & product range has expanded..
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Old 07-03-20, 11:08 AM
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Obviously a mid-90ís, what bike is it?

I would guess that is an old 90ís Suntour fork not a newer one. Maybe 63mm, but no more than 80mm. You can probably use an 80mm.

While thru axles are better, mountain bikers have probably ridden millions(?) of miles with QR and discs. Just make sure they are tight and use steel internal can QRís.

There are cheap new 80mm forks on eBay for less than $100 if you want cheap and feel you need suspension. If you donít need suspension you can go rigid. You also have to weigh the cost of the disc system.

If your old Suntour fork works well, donít get rid of it. I donít know who made it. I wasnít aware Suntour made (labeled) forks back then.

And it doesnít matter what you paid for the bike, if it is pretty much unused, in this market it would probably fetch more than $100. Between the pandemic buying and a nostalgia for 26ers, I donít see a lot of good cheap ones out there. But Iím not flipping either.

John
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Old 07-03-20, 12:08 PM
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OK: I'm going to assume that you are riding on pavement and sometimes in the rain.

First, ditch the knobby tires; they have poor traction on anything but mud or loose gravel. Slick tires provide more surface area and therefore better grip to the road. High-pressure slick 1.5" tires will roll a lot faster as well.

Second, upgrade your V-brakes and pads. It looks like you have cheap stamped-steel V-brakes found on department-store bikes. Inexpensive Shimano V's are worlds better, and have better stock pads.

If you want a better all-round bike, also get rid of the suspension fork, which unless your commute involves travel over head-sized rocks, is a heavy and unnecessary impediment. It adds 2 pounds of useless weight, saps your pedaling energy due to suspension bob, and has less precise steering/handling than a rigid fork.

26" wheels are fine; 27.5" is dead, and 29" wheels and tires are heavy.
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Old 07-03-20, 06:56 PM
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I guess you are going to use mechanical front disc and v-brake for the rear.

John
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Old 07-05-20, 04:15 PM
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Originally Posted by Dave Mayer View Post
If you want a better all-round bike, also get rid of the suspension fork, which unless your commute involves travel over head-sized rocks, is a heavy and unnecessary impediment. It adds 2 pounds of useless weight, saps your pedaling energy due to suspension bob, and has less precise steering/handling than a rigid fork.
I just noticed something while scavenger hunting in local second hand market.
It was impossible for me to even find a 26 inch threadless fork that's rigid.
I either find
- 26 threaded rigid/suspension v-brake
or
- 26 threadless suspension v-brake/disc brake

Only in 700c can I find a threadless fork that's rigid.

Funny that by 2010, rigid mountain bike fork actually becomes a niche item you have to special order to get.

Last edited by CaptainPlanet; 07-05-20 at 04:48 PM.
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Old 07-05-20, 04:35 PM
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That's certainly the trend of things but I don't think your local market is an accurate representation of what's available.

I'll bet you $100 that v-brakes with salmon pads and compression-less housing stops as well or better than any mechanical disc brake you can get on your bike.

Why are you so insistent on ignoring good advice that will save you time and money?
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Old 07-05-20, 04:50 PM
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I was looking to see if I could find a rigid 26" threadless fork on the used market, after reading some of the advice, because ebay fork is not cheap, but I couldn't find one used.
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Old 07-05-20, 05:01 PM
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Originally Posted by CaptainPlanet View Post
I was looking to see if I could find a rigid 26" threadless fork on the used market, after reading some of the advice, because ebay fork is not cheap, but I couldn't find one used.
Once more. Slowly.

Cables, compression-less housing, salmon pads, and some steel wool to clean up your rims. Should run you about $30-35 for the bike. It'll stop better than you'll ever need it to. Double the price if you get a shop to do it but I bet you can handle it.

You're not going to get a fork under $75. Probably closer to $200. Now you still need to go get a front caliper. Or ideally, a hydro caliper with lever. New front wheel or rebuild with new hub. Rotor. And you still have v-brakes in the back. Let's be very generous and say $300

Is it worth trying to get those v-brakes working?

​​​​​​
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