Author Topic: Steering Stabilizer on a Thorn Nomad  (Read 8762 times)

crazytraveler

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Steering Stabilizer on a Thorn Nomad
« on: October 18, 2014, 01:28:36 PM »
Any way to fit any Steering Stabilizer on a Thorn Nomad bike? Do you know any model that fit for this model?

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JimK

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #1 on: October 18, 2014, 04:16:45 PM »
With the front brake mounted behind the forks? Seems mighty tricky!

Danneaux

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #2 on: October 18, 2014, 04:21:45 PM »
Hi, CT!

I've been wrestling with this problem myself recently. The answer depends on a number of factors, including what you want a steering stabilizer to accomplish.

I've found Thorn 26in-wheeled tourers can exhibit quite a lot of wheel flop at rest, the result of relatively high-trail geometry that makes for lively handling at low speeds and greater stability as speed increases. "Wheel flop" means the front wheel/handlebars/fork tends to spin to one side or the other when at rest, a tendency made more pronounced by a handlebar bag and front panniers. It has affected every one of my loaded touring bikes to some degree, so Thorn is not unique here. I've addressed the problem in part by setting my parking brake when stopping -- I prefer the Bike Brake bands that sit flush with the handlebars when unused, yet securely hold the brake when needed. They have not yet stretched out, nor have they broken down in the hot desert sun. Here's a link to them: http://www.bikebrake.com/

One problem with wheel flop is the fork can turn enough for a dyno headlight to foul against the downtube or -- depending on configuration -- for the handlebar ends to hit the top tube.

Thorn have recently come up with a steering *limiter* to address just this problem. I comes in two flavors to fit the Nomad and Raven/RavenTour series of frames. You can see the limiters here:
http://www.sjscycles.co.uk/thorn-steering-lock-limiter-and-striker-for-stepped-395-365-mm-head-tubes-and-1-1-8-steerers-prod34957/?geoc=us (For stepped head tubes, as on the RavenTour)
http://www.sjscycles.co.uk/thorn-steering-lock-limiter-and-striker-for-37-mm-head-tubes-and-1-1-8-inch-steerers-prod34956/?geoc=us (For unstepped head tubes, as on the Nomad)

These require 10mm of head tube above the top tube, and they require a similar amount in spacer width above the headset (some juggling of spacers will be required). The lower portion of the limiter clamps around the top of the head tube, while the upper part clamps on the steerer. This (rather than the stem or a Thorn Accessory T-bar) holds the headset in adjustment and must be loosened if you wish to adjust the headset. Thorn caution it is intended to work at lower speeds or while at rest to prevent light bashing and handlebar contact, but is not intended to protect the top tube from potential handlebar damage in the event of a substantial crash/fall while riding.

My problem is my Nomad has only about 8mm of head tube standing proud above the top tube weld (the weld forms a small fillet). To fit the lower portion of this steering limiter, I'd need to mill some aluminum off the back, which is no problem. My concern is if it was forced to rotate in a "big" crash, it could damage that frame junction rather than just spinning off some paint. Dave Whittle has found the upper (steerer-mounted) portion is more likely to rotate, so my concerns may be moot. By the way, the parts of Thorn's steering limiter are available separately, so if I do decide to mill the lower clamp and it is unsuccessful, I can buy a replacement for just that part. One solution I am considering involves milling-off 2mm of the rear clamp ring *between* the clamp ears. That should work nicely to address my more limited clearance.

Tr!ckStuff in Germany make a headset with a built-in limiter, but it is expensive and I don't need to replace my headset yet. Some manufacturers braze the lower stops onto the sides of the upper head tube. These can have problems as well, rusting at the contact points if made from something other than stainless steel.

The other approach to the problem of protecting top tube and lights from wheel flop is the true steering *stabilizer*, as typified by Hebie's entries in the field, shown here:
http://www.sjscycles.co.uk/hebie-steering-stabilizer-for-bipod-stand-usage-hbp4-prod18782/?geoc=us
http://www.sjscycles.co.uk/hebie-steering-stabilizer-prod33857/?geoc=us

One version has a "filled" spring intended to prevent pinched fingers, while the other is a full elastomer design.

These typically attach to the nut on the rear of the front brake mount -- or its equivalent -- on a through-drilled fork crown. Thorn's crowns are not through-drilled and instead use what amounts to a daruma for mounting the front mud guard. This takes the form of a plate with two threaded holes, brazed into the bottom of the steerer. To make a Hebie (or similar...BBB make a competing model, I've seen one my M-wave on my last tour, as well as some unbranded from the Far East) stabilizer work on a Thorn, you'd need to make a simple plate with two through-holes to bolt to the mud guard mounting plate in place of some of the spacers used. It should work fine and still clear the top of the rear-mounted v-brake; I don't think the rotational torque would damage the plate's connection to the frame. The other end of the stabilizer attached to a clamp around the downtube...usually just past the butted end section. I've read no reports of problems, but it is something to keep in mind.

Hope this helps. I'm still investigating myself. The ultimate solution may be to fit both the Thorn *limiter* and a Hebie-type *stabilizer*.

Best,

Dan.
« Last Edit: October 18, 2014, 07:17:43 PM by Danneaux »

crazytraveler

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #3 on: October 19, 2014, 09:53:48 AM »
I am not worried about the top tube. I have 2 problems that I want to address with the steering stabilizer.

1. When parked, if I use my click-stand, even usen the "hand-brakes" that I already have, the bicycle tends to fall because the front wheel turn itself.

2. When cycling slow, mostly up-hill, it is really hard to keep the bike straight. I am carrying a lot of weight, and a lot of it in the front, which make it harder. But I think with a steering stabilizer this problem could be addressed.

With a Hebie style mounted as you described you think my problems would be addressed?

Cheers!
Cycling around the world on a Thorn Nomad!
http://en.thecrazytravel.com/

Danneaux

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #4 on: October 19, 2014, 04:39:11 PM »
Hi, CT!
Quote
I have 2 problems that I want to address with the steering stabilizer.

1. When parked, if I use my click-stand, even usen the "hand-brakes" that I already have, the bicycle tends to fall because the front wheel turn itself.
It is possible the steering stabilizer will help here, but no guarantees if the bike is *really* heavy. Our own JimK sometimes has used a nylon webbing strap through his front wheel and around the downtube to prevent the wheel from turning to the side or moving much if any fore-aft. Fixing the front wheel with a strap like this turns the bike into a single, fairly rigid panel. Here's a fancier leather version: http://www.ecovelo.info/2010/06/09/homegrown-cargo-rack-stabilizer/

The Hebie steering stabilizer helps damp movement, but doesn't eliminate it completely -- the wheel/fork can still turn a bit side-to-side and is still free to roll. Hebie stabilizers seem most effective when dealing with a bicycle standing on a two-leg kickstand, where a heavier rear load elevates the front wheel, increasing the chance it will flop side to side. From the ones I saw while in Austria, it can work well for these purposes if the bike is parked on ground that is fairly level left-to-right and the front load is not excessive. When stopped with the bike leaning to one side or astride it, the wheel can still turn a bit, causing the bike to arc to one side or another. The arc is less severe, but still there to a degree. Cranking the stabilizer tension down helps, but can cause the anchor bracket to rotate at each end, damaging paint or bracket (and potentially, the frame tubing in the unbutted sections where most stabilizer clamps are attached.

If you want to try the Hebie concept more cheaply, then M-wave offer a design often seen (and made available) by makers of cargo bikes: http://www.amazon.com/M-Wave-Bicycle-Steering-Damper-Black/dp/B007Y5GULW If you read the reviews carefully, you'll see the effectiveness of the spring-type stabilizers depends greatly on the crown mount and the length of the mounting bracket there. You can see the Yuba Mundo version intended for their bikes with a build-in anchoring point: http://www.calhouncycle.com/productcart/pc/viewPrd.asp?idproduct=3292 Note the seller's caution that handling while riding won't be affected appreciably unless it is set really tight (and that can have other consequences). VeloOrange offer a version as well: http://store.velo-orange.com/index.php/vo-wheel-stabilizer.html

Please note Hebie make two versions...and for different-sized downtube diameters. The first version uses a plate that attaches to the rear of the fork crown using a bracket. The second version is intended for suspension and similar forks that may not have a through-hole. This first version will require fabricating a custom bracket to fit to Thorn's two-bolt mudguard mounting plate, brazed into the bottom of the steerer. The second version won't fit because of that same plate blocking access to the bottom of the steerer.

I think I'd check to make sure your front brake pads are set close to the rim so the "hand-brakes" you already have will be most effective. If the wheel itself cannot spin, then the bike is less likely to fall as a result of the fork turning.

There is another option, but I can see a number of potential problems with it: http://www.toynbee.co/spokebug.html
Quote
2. When cycling slow, mostly up-hill, it is really hard to keep the bike straight. I am carrying a lot of weight, and a lot of it in the front, which make it harder. But I think with a steering stabilizer this problem could be addressed.
I could of course be wrong, but I don't think the steering stabilizer of Hebie's design will help so much here. I think the solution is to place less weight on the front...and/or go with more leverage in the form of a longer moment arm between your hands and the steering axis. You can accomplish this with wider handlebars, a longer stem, or both. On my Nomad, I am running 44cm compact drop handlebars and a 60mm stem extension. GThe distance or moment arm from the "hand pocket" on each brake hood to the steering axis is about 300mm on each side. I find this gives me plenty of leverage even with loaded front panniers and a handlebar bag.

I've found my two Thorn bicycles (my former Sherpa Mk2 and present Nomad Mk2) handle better with more weight at the rear; I found the same with the RavenTour loaned me by AndyBG for my big tour last summer. Thorn touring bikes have relatively high trail, at least compared to the low-trail designs of the great French constructuers and their imitators today. Higher-trail bikes handle better with more weight at the rear; low-trail bikes do much better with (relatively and absolutely) more weight at the front. Bikes with higher trail geometry tend to give lively handling at slower speeds that becomes progressively more stable with speed.

Where you're riding a Thorn tourer, then Andy Blance's fork-loading recommendations in the relevant brochure will ensure the best handling possible. This link details where AndyB feels weight should be placed: http://www.thorncycles.co.uk/forums/index.php?topic=4515.0

While I wish it would make a big difference, your second concern is even more difficult for a stabilizer to address than the first. it would have to be really, really tight to overcome the torque placed on it while riding with a heavily laden front end...and that can cause other problems. If you try it and it works, please let us know, as I'm keen to see what effect it might have. Meanwhile, this user review may prove helpful: http://cyclingabout.com/review-hebie-695-steering-stabiliser/ More discussion here: http://forum.ctc.org.uk/viewtopic.php?f=5&t=54112 Some of the people here relate experiences that make it sound like the ideal solution to your problem. I expect in the end it might be a YMMV issue: http://www.bigboxbikes.com/viewtopic.php?f=17&t=755

As an aside, bicycle steering stabilizers are much different from the steering dampers used on motorcycles: http://en.wikipedia.org/wiki/Steering_damper  Those use friction or hydraulic damping instead of the increasing tension from a (metal or elastomer) spring. If you had a sturdy triple-tree as on a motorcycle and more substantial frame tubes, then a cheap aftermarket motorcycle damper might fill the bill, but I'd be very leery of attaching it to a conventional fork blade and downtube.

Have you seen the Hopey dampers intended for downhill MTBs? I think something like that *might* come closer to addressing your second concern, experienced while riding. See: http://www.hopey.org/ Video here: http://www.youtube.com/watch?v=XIOX5xmKBkg They are not inexpensive at $220.

A final note: Remember, at low speeds, steering input is greater than at high speeds, where the bike is turned largely by leaning. Restricting free movement of the steering too much could make low-speed handling ehm, "difficult", resulting in a fall. There can be too much of a good thing, including steering stabilization. Believe it or not, feathering the front brake occasionally while riding uphill at slow speeds can do wonders to aid steering stability, and might be worth a try.

Best,

Dan. (...who is usually pretty stable)
« Last Edit: October 19, 2014, 07:14:16 PM by Danneaux »

crazytraveler

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #5 on: October 21, 2014, 11:35:52 AM »
Thank you very much, one more time Dan.

I think I will try to redistribute a bit the weight, it is just I keep the heavy but fragile stuff in the front since I think it is less prone to get hit there... And I will widen the position of the grips since I still have my handlebar uncut to be able to do just that.

I will let you know how does it feel afterwards.
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onrbikes

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #6 on: October 21, 2014, 02:40:53 PM »
What about something like this

https://www.crazyguyonabike.com/doc/page/pic/?o=Sh&pic_id=1432168&size=large&v=1

Am sure you could rig up something yourself to suit.
I too am thinking to do something similar

crazytraveler

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #7 on: October 21, 2014, 02:48:19 PM »
What about something like this

https://www.crazyguyonabike.com/doc/page/pic/?o=Sh&pic_id=1432168&size=large&v=1

Am sure you could rig up something yourself to suit.
I too am thinking to do something similar

But if it is only going to help when parking it is not "enough" for me, I would want it to help when riding.
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richie thornger

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Re: Steering Stabilizer on a Thorn Nomad
« Reply #8 on: October 21, 2014, 05:28:11 PM »
I used a wedge of wood like a door stop under the wheel when I knew it was going to be a problem :)

I'd rather have a bottle in front of me than a frontal labotomy