Are suntour forks total crap??

After wrecking my surly fork due to spinout I am on the hunt again. What I am gravitating towards is the type of steel forks with dropouts that are beefier resembling those used on bmx forks. Some of these have extra holes where a custom made plate torque arm could be made similarly to the vast choices one has with the rear torque arms mountings. I don't see the big choices here aside from the suntour company. They have the right specs for 26inch fat tires and the dropouts look substantial enough and supposedly they're steel. The price is too good to be true but after reading about their melting and casting processes I don't see the down side of their product. So how about feedabck from those that have used them? BTW does anyone sell ony the front torque arms plates as that is the part that usually gets messed up on spinout? It doesn't make sense to have to buy the 2 pieces each time.

I don't know about all of the Suntour forks, just the cheap ones, but I've used two kinds that I know of.

I have two identical Suntour something-2000 black steel forks, one of which I welded a disc-brake mount to, the other of which is still as-is. The former has been used on CrazyBike2 for some time, I forget how long but maybe a couple of years (EDIT: more like 3-4 years, after reviewing posts in my CB2 thread) total (not counting the long break starting a bit before the housefire till a few months later), and it's still mostly ok, even after a couple of crashes (one during the DeathRace where I broke my ankle), and I haven't screwed up the dropouts yet, even with regen and accel on a 26" 9C 40A 12FET all the time on my daily commutes. The bushings (nylon? dunno) between the inner tube and the outer fork itself are wearing, as the fork rocks back and forth there if I hold the brakes and push the bike forward or backward. I'm sure they could be replaced, but I haven't tried taking the fork apart to see.

Now it's on my trike, with an X5304 (no torque arms yet) on a 33A controller (no regen yet, and apparently "soft start"). Still havent' screwed up the dropouts, but it probably would if I used it with the X5304 and regen and hard start with the 40A unit, without torque arms (the axle isn't long enough for them).

The other one, I cant' remmber but I don't think I've used it yet. I'm sure there's info on it in my CrazyBike2 thread, but nto sure where.

EDIT: found the post:
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=12500&p=954759&hilit=suntour#p954759
it shows both types of fork, the steel (black) and the alloy (white).




I also have a suntour xcv3 alloy fork, no rim brake bosses, just disc, but I added my own with hose clamps/etc (see the crazyBike2 thread and search for "suntour" in it for the posts about that). It's a lot better fork than the other one, but being alloy, I wouldn't trust the dropouts without torque arms. I used wrenches, and so far it's survived fine on CB2 with the same usage the other one had, but it's only been on there a few months.


FWIW, if axle length permits, I'd *always* use hefty torque arms on any front hubmotor, regardless of how good the dropouts might be rated or experienced, unless you actually built them yourself as pinching/clamping dropouts with as much axle-flat-mating surface area as possible given the axle length.


If you wanna use your existing forks, you can look at a thread from this week where John in CR responds to Cwah with a way to fix his broken dropout fork. That's how I'll be fixing some Manitou Skareb forks I screwed up, someday when I have time/materials.

The steel forks are what we call pogo sticks. They come on bike shaped objects.

They have a spring, that's it. No oil, no dampening, no rebound adjustment, not even a preload adjustment.

Next level up is usually alloy, but does at least have a preload adjustment. Still a pogo stick with no oil inside.

This type of fork can be tolerable only on street, and even then the street must be in decent shape. Off road, a pogo stick fork is useless. It will bottom out constantly. Generally once you get on the bike, only about 20mm of travel left.

The upside of the steel suspension forks is they don't break as easy as alloy. I still suspect you cracked those forks with the first tightening of a nut though. Do it right, with two c washers, and two good torque arms, and you should be able to ride thousands of miles on an alloy fork.

If you dig deep enough, there is a review thread on c washers, and grin torque arms, showing proper installing on alloy forks. From about 2009 or so when I put them up.

Suntour does make a few forks that are better than their usual crap, but nothing that really works (and weights) to the standards of serious riders.

Forks that are tuning and working fine are common: Rockshox, Fox, Marzocchi, Magura... All making a line of forks ranging from "AM" to "WC". They can be tuned for any bike and rider and style, and service parts are easy to source.

There are some high end manufacturers that are making only a few specific models: eg. DVO, BOS

Some tuning specialists also make their own upgraded versions of various common models of forks, and selling upgrade kits to make your own.

A good fork that you like to ride, lives through many bikes. Once you know it well, that you can fine tune and service yourself... It is priceless. When you sell the bike, you just buy any used fork for it and you keep yours for the next build. That is why we are willing to invest big bucks in the best forks.

Thanks to those that gave experience input on the suntours. I am basically a street rider so the suspension thing isn't a consideration for me really as much as the
seemingly beefier dropouts they have that might accomodate homemade torque plates for the front hubs. With the rigid forks the lawyers lips are small and the c washers don't seem to sit as well or in the case of antirotational washers in MTB type dropouts that really assist have a great lip to stop. I am somewhat surprised that in the advent of ebikes no one has come up with beefier front dropouts as they are all designed for non electric axles. As easily as these steel dropouts and torque arms gave way it is a small costly sum to pay 60-70 bucks for torque arms. I looked up the proper (?) sequence of washers and such for the motor after 1st spinout but each manufacturer gives a slightly different version. On my steel fork I had one spin out months ago but was able to salvage the fork. After this second spin out I switched sides for the torque arm as the axle had been really stripped and I sought more "axle grip"for torque arm. My sequence on wired side was c washer, flat washer , lock washer torque arm and bolt. You can see by the pics it was this side that really got a lot of spin out effects. On the right side to compensate for the stripped axle section in securing it a second time I used c washer, 2 spacers to allow me a place to where the bolt would grip. I really though I had a good setup on the last install. I can't see what I'm missing. Bear in mind the wired side on these mounting pics does not show a totally tightened bolt..I just reconstructed for your examination. OH BTW I have to change the motor shaft now ....( I hope I can ) I can't find the part yet but some other manufacturers look like they use the same axle. uugh...the side with the remaining torque arm is what spun out this time. The dropouts now measure about 13mm...and the c washers..well fuggedabadit..

No matter what path you are going, I suggest using doctorbass torque arms. https://www.endless-sphere.com/forums/viewtopic.php?f=31&t=29129

Use some steel forks, any will do, fix these to the dropouts and the dropouts should be fine forever. Open mouth design means installing and removing the wheel from the fork is as easy as typical bicycle forks are.

I know nothing about the suntour forks specifically, but if are concerned with harsher bumps in the road, I'd use forks that can hold a wider tire rather than a slimmer one.

Seriously, that hose clamp over, the axle stuff is a curse in disguise.

2 inch torque arms on the delicate dropouts generally found on front steel forks? That would look like hockey pucks and I don't know if they would even align with the fork dropouts. I assume they'd be epoxied to the exterior of the drops. I've always seen pics of back fork mounts.

bowlofsalad said:

No matter what path you are going, I suggest using doctorbass torque arms. https://www.endless-sphere.com/forums/viewtopic.php?f=31&t=29129

Use some steel forks, any will do, fix these to the dropouts and the dropouts should be fine forever. Open mouth design means installing and removing the wheel from the fork is as easy as typical bicycle forks are.

I know nothing about the suntour forks specifically, but if are concerned with harsher bumps in the road, I'd use forks that can hold a wider tire rather than a slimmer one.

Seriously, that hose clamp over, the axle stuff is a curse in disguise.

Click to expand...

Given what I see in your pics, definitely go find that recent thread by Cwah about forks, and do what John in CR did on his, as posted in that thread.

No more worries, no torque arms needed.

Ok, looks like you did have the C washers. It also looks a lot like you ended up riding a while with a loose nut, so any slack in the single torque arm was grinding away some metal for at least a short while, before the final spin out.

All I know is what worked for me. Two c washers, two torque arms, keeping sure the nuts were tight with frequent pre flight checks, and some filing of the dropout notch, to get a 14 mm axle deeper into the dropout. Yours look like 12 mm, so not so much need to file deeper, but more need to have a very tight fit on the TA's.

Go ahead and get some cheap steel forks, but get another torque arm, so you run two.

Your threads are so mashed, looks like maybe the axle is ruined enough on that motor to prevent anything from working right. Looks pretty mangled, like a nut all rounded off by a loose wrench.