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Down South Yooper
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Discussion Starter · #1 ·
Hi everybody, I'm looking for suggestions on a rigid fork for my 1st tandem build.

I'm looking for:

1 1/8" threadless, disc brake tabbed rigid fork that will accommodate a 650b knobby tire.

The fork that is being replaced is ~400mm, so I'd like to keep it around that if possible, but I can likely live with the effect that a longer fork has on tandem geometry.

Forks I'm considering:

Surly 1x1
Surly Instigator
Salsa Fargo fork
Salsa Cro-moto 29" disc fork

Any feedback on those forks? Any other recommendations that I'm overlooking? I could go with a thru axle as well, as I don't have hubs yet, but I've only seen the Funn fork that would really be a possibility there..

Thanks.

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Down South Yooper
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Discussion Starter · #3 ·
Trails4Two said:
Haven't used any of them, but I'd drop a call to both manufacturers and ask them about using their forks on a tandem.
Haven't done that yet, but I'm guessing that the official answer from the MFG will be no, they're not rated for tandem use. Haven't found a rigid MTB fork specifically marketed for tandems..

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Long Live Long Rides
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the way it goes

I suspect that that is the answer you will get, but both of those companies are small enough they might be willing to talk to you about it. My guess is that the big issue would not be the support of the fork, but it's ability to withstand the kind of braking forces involved.

Good Luck!

P.S. I think Vicious Cycles makes a 29er rigid for tandem use
 

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Down South Yooper
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Discussion Starter · #5 ·
Got an email into Surly regarding their 1x1 fork. I'd prefer to use the 1x1 due to the shorter a-c length vs. the instigator. The 1x1 is only 1/2" longer than the stock fork on my tandem, probably largely unnoticeable. I've read in a couple spots that surly will actually endorse the instigator fork for tandem use, have not ready that about any other models tho.

The HT angle on my tandem is supposed to be 70 degrees, so I probably have some room to run a larger fork before the HT angle gets out of whack too far, but if a 1x1 fork will work (ie they don't email me back and tell me horror stories about breakage) that's probably what I'll try.

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Professional Crastinator
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We do use an Instigator fork on a bike that was not designed for suspension, so it is a bit longer than stock, but there are benefits to that.

Please read below from this thread and check the link:

Fleas said:
I'll second the motion.

I posted here about a longer fork on a '98 MT1000:
http://forums.mtbr.com/showthread.php?t=443709

And now that we do have a 2.3 Nevegal up front and a 2.3 High Roller in back, and 34T rings replaced the 38's, the bike is even more capable. I would not compare the handling to a schoolbus, though. Besides, it's green. :D
In the interest of science, I will get a digital angle measurement of the HT angle as it sits now.

-F

PS - and I do still have the 1998 catalog that came with the bike. Geek away!
-F
 

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Down South Yooper
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Discussion Starter · #7 · (Edited)
Fleas said:
We do use an Instigator fork on a bike that was not designed for suspension, so it is a bit longer than stock, but there are benefits to that.

Please read below from this thread and check the link:

-F
Yep, I was reading that last night. I have very good confidence that an instigator fork will physically work and actaully be endorseable by Surly, but I'm still concerned about the overall length of the fork, the Instigator fork will be almost a full 2" longer than the current fork, whereas the 1x1 is ~1/2" longer.

I don't know the wheelbase of my frameset (I got too lazy to measure it last night), but I'm guessing that 2" of extra front end height is going to result in excessive front end flop due to choppering the bike out..

I have another option I'm waiting to hear on as well, that might solve all my problems beautifully. Rawland Cycles makes a 650b/29er rigid fork that is ~404mm long and is complete with disc tabs. What I don't know (and have inquired about) is whether they're available separate from the framesets and whether they have any tandem concerns.

I realize that most manufacturers are going to shy away from authorizing use of their fork on a tandem, and I don't blame them. I'm looking at it from a standpoint of a new fork being stronger and better designed than a 18 year old unicrown fork. In a side to side comparision, I'm willing to bet that the modern fork (be it a 1x1, instigator or the rawland) is going to be stronger than the stocker, even if it's not officially rated for tandem use..

Plum

P.S. Surly confirmed the use of the Instigator, but not the 1x1.
 

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Down South Yooper
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Discussion Starter · #8 ·
Rawland confirmed that they aren't comfortable with their fork on a tandem either, which was expected. They did look into it though, so I appreciate that.

I finally looked at the WB of the bike last night and the effect that a longer fork will have on it. Benefitting from the WB, I only gain ~.75 degrees per inch of additional fork length. Based on the recommendation of Surly to stay away from the 1x1 on a tandem, using the instigator @ 447mm long will give me a HT angle of ~71.5 degrees. Probably within the range of acceptable, if not on the slow side of things.

Anything else out there I should be looking at? I can't be the only one wanting/riding a rigid fork on a tandem out there.

Thanks.

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SO I take it that the bike was not originally designed around a 650b platform.......
If that is the case are you accounting for the change that is incurred by switching to the 650 b from 26 inch? Neomoto or Quasimoto?

Why are you so averse to a suspension forK? once you factor in sag a Marzocchi DJ would not be too far off.

Unless its for a townie or just cruising about I think you would be well served with a Marzocchi DJ with a 20mm thru axle.

If you want the advantage of 650b as far as the ability to roll over things, I would suggest just going with a 2.5+ downhill tire on your 26 inch wheel. That extra volume goes a long way.

All of my half bikes were or are rigid, and I appreciate the precise steering, but when I am on the tandem for any length of time, I want some squish. Plus it helps with weighting and unweighting the front end in technical sections.

That being said, I would be more frightened of a 9mm QR failing than a surly steel fork.
 

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Down South Yooper
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Discussion Starter · #10 ·
agriholic said:
SO I take it that the bike was not originally designed around a 650b platform.......
If that is the case are you accounting for the change that is incurred by switching to the 650 b from 26 inch? Neomoto or Quasimoto?

Why are you so averse to a suspension forK? once you factor in sag a Marzocchi DJ would not be too far off.

Unless its for a townie or just cruising about I think you would be well served with a Marzocchi DJ with a 20mm thru axle.

If you want the advantage of 650b as far as the ability to roll over things, I would suggest just going with a 2.5+ downhill tire on your 26 inch wheel. That extra volume goes a long way.

All of my half bikes were or are rigid, and I appreciate the precise steering, but when I am on the tandem for any length of time, I want some squish. Plus it helps with weighting and unweighting the front end in technical sections.

That being said, I would be more frightened of a 9mm QR failing than a surly steel fork.
Actually, the bike was (more or less) designed around a 650b wheel. The 700d 'experiment' by GT only varied in diameter by 3mm from the 650b, so I'm not making any major changes that way.

My anticipated use doesn't likely involve a lot of off-roading for now, just because the tandem is difficult to move in a vehicle, and my wife and I don't get the time to ride together often, unless we bring our two small children along in the trailer. Mostly we'll be cruising from the house around town.

My tandem frame will accommodate anything from 26 x 2.5+ tire, a 27.5 x 2.3 and a 700c x ~35 or so. It'll be pretty versatile. We can throw a set of 29er wheels in it with some beefy slicks and do some road touring, or throw some fat 26" wheels on it and go mountain biking, so a 20mm will hurt my interchanability some, as I don't have anything else with a 20mm hub currently (and the cost of the 20mm stuff).

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Derailleurless
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Take a look at Surly's Big Dummy fork. Axle to crown height is 425mm. That will result in less than one degree of head angle change, assuming ~ 1° per 35mm for a typical tandem wheelbase. It should stand up to tandem usage since it was designed for a heavily loaded bike.
 

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Down South Yooper
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Discussion Starter · #12 ·
Speedub.Nate said:
Take a look at Surly's Big Dummy fork. Axle to crown height is 425mm. That will result in less than one degree of head angle change, assuming ~ 1° per 35mm for a typical tandem wheelbase. It should stand up to tandem usage since it was designed for a heavily loaded bike.
I considered this as well, but Surly will only endorse the Instigator for tandem use.

Will other forks work and not fail immediately?, probably, but they can't endorse them for tandem use. I have an email into salsa currently, just to verify, but I assume that the answer will come back the same..

I'm not anti-suspension fork, but I don't want to go through the expense and hassle of one when i don't really forsee needing one at this time. I can get an instigator fork for ~$75 and it'll be compatible with my 29er wheels, 26" wheels and my 650b wheels. A through axle rigid fork would be fine too, but they're almost as much as a sus fork, they have limited options, and I have the same 20mm hub dilemma regarding interchangability.

I will likely go with a bolt on front hub though, just for some added security. I've never heard of a 9mm QR breaking, as it's only in tension (holding the fork legs together), but a bolt on hub like a Hope pro 2 would probably be warranted. Plus, I can swap out end caps for a larger thru axle in the future if need be..

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Plum said:
I considered this as well, but Surly will only endorse the Instigator for tandem use.
The Dummy is rated to carry 200 pounds of cargo, plus the rider. I can't see how this isn't applicable for tandem use. I guess it depends on how cautious you want to be. Maybe Surly can give you a little bit of detail behind their decision?
 

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Down South Yooper
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Discussion Starter · #15 ·
JediSith said:


I use a DMR Trail Blade Fork with a 203 Rotor. No problems. I am thinking of selling this fork to get a cromotion fork. Let me know if you are interested.
JediSith, check your PMs..

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Down South Yooper
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Discussion Starter · #16 ·
Salsa confirmed that their forks are single bike only.

The DMR line of dirt jumping forks looks promising. Shorter A-C than the instigator, plus the alternative of a 20mm rigid fork, which has been recommended by others above.

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Student of the Bike
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Speedub.Nate said:
The Dummy is rated to carry 200 pounds of cargo, plus the rider. I can't see how this isn't applicable for tandem use. I guess it depends on how cautious you want to be. Maybe Surly can give you a little bit of detail behind their decision?
I went this direction on my tandem just this week. I've also added a 29er front wheel to get my BB's up higher. I looked over the weights of the Surly forks and the Big Dummy still weighs out to be a pretty stout fork. Of course I know its not tandem rated but I'm willing to take that risk. We've had one ride on it so far and I'm very pleased with the changes. My biggest problem has been pinch flatting the front tire.

I'll post up some photos in a new thread.

Later,
CJB
 

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Down South Yooper
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Discussion Starter · #18 ·
CBaron said:
I went this direction on my tandem just this week. I've also added a 29er front wheel to get my BB's up higher. I looked over the weights of the Surly forks and the Big Dummy still weighs out to be a pretty stout fork. Of course I know its not tandem rated but I'm willing to take that risk. We've had one ride on it so far and I'm very pleased with the changes. My biggest problem has been pinch flatting the front tire.

I'll post up some photos in a new thread.

Later,
CJB
How is the 29er clearance in the Big Dummy fork? I have committed to a DMR Trailblade QR, but it's always nice to see how other forks are working out, especially with the shorter AC length. I'm really disappointed I couldn't get into a Rawland fork, that would have been the ideal.

I was (and still am) on the fence regarding the 20mm option, but I'm going to give the QR a try, probably with a bolt on front hub. I'm planning on a Hope front hub that's easily convertable between QR, bolt on and 20mm, so if I decide to change down the road, I'm only out the cost of the conversion pieces.

At worst, I'll be looking for something to replace the trailblade down the road, but if I get to that point, I'll probably be looking at suspension forks, I think. I need a ton of steerer, so anything I decide not to use should have a pretty good range of re-usability with it.

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Long Live Long Rides
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another possibility

Not nearly as hip as the Salsa or Surly, but you could look for a take-off from a Cannondale tandem. The "Fatty" rigid is heavy duty aluminum and can be found with disc mounts for both 26" and 700c. As I said, it might not be pretty...
 

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Down South Yooper
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Discussion Starter · #20 ·
Trails4Two said:
Not nearly as hip as the Salsa or Surly, but you could look for a take-off from a Cannondale tandem. The "Fatty" rigid is heavy duty aluminum and can be found with disc mounts for both 26" and 700c. As I said, it might not be pretty...
I would have considered that if I had seen one come up for sale. Tandem stuff isn't exactly commonplace or necessarily easily found. I have a fork coming Friday, according to UPS, and I'm hoping to have everything buttoned up by the spring sometime, in time for summer riding.

I need to do some fundraising for a new wheelset though..

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