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Ride More - Suffer Less
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Discussion Starter · #1 ·
I rode a friends Sultan this past weekend and really liked the bike overall. I am going to get one but am now looking at how to build it. Im not sure his build suited me well. I am used to riding a long travel (26) triple clamp fork that is extremely solid and stiff.

The Sultan was equipped with Team Reba forks and Magura Marta brakes. In low speed braking the forks would chatter forward and aft from what appeared to be the way the brakes were grabbing the rotor. Brakes worked awesome when you had some speed but strange feel in slower speed technical sections. The fork forward and aft flex just didnt seem like a good thing. Anyone follow me on this?

Im 220# and like my bike to feel solid with minimal flex, especially up front. What are some real world experiences on fork options, I hear lots of good on the Fox 32, how about some 140mm options?

Is that rotational grabby feeling normal with those califlower type rotors? Im still running my 10 year old hayes with round discs so maybe Im just not used to the feel?

Thanks!
 

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Were the forks QR or Maxle? That would make a difference. You are also going from triple clamp to regular fork so you'd feel the difference on a 26er never mind on a 29er. You are comparing apples and oranges.
There are few longer forks than 120mm for 29ers - you have to ask why? 29ers seem to take up more of the bumps so most people accept that 29er wheels 'give you' an inch as it were. I can't explain it, but I can feel it when riding. I can't comment on the brakes either. Fox are bringing out their 29er fork with a tapered steerer. When a 29er builder makes a frame to take it that might give you additional stiffness.
 

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Discussion Starter · #3 ·
Maxle. I agree, the triple will never compare, but its my point of reference. Must be something stiffer than those Reba's. Was just curious on the 140mm options. For my riding style these days 29 wheels / 120mm seems to be plenty. I agree the 29 wheels just flattened out the bumps.
 

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One of the reasons that the tapered HT is becoming more popular with manufacturers is to help deal with the flex in the crown-steerer tube interface under braking. Hopefully Turner will go that direction with the 2011 Sultan.
 

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Dunno if you were riding a dedub Sultan or V1 but here's my V1 build http://forums.mtbr.com/showpost.php?p=5706142&postcount=1. FWIW I'm ~215 - 225 geared depending on how much beer I drank. Maxle is a big step up for us larger fellas. Like tootall said, comparing triple clamps to a single crown fork isn't realistic.
 

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I had a friend ride my DW sultan and he really liked it too. The deal killer for him was the post mount in the rear- he uses rohloff's doesn't allow for a clean mounting option. Anyways as far as front forks go I have been extremely happy with my Maverick duc32. Granted shorting my self 0.1" travel compared to rear end. 4lbs., dual crown, and 24mm axle are some definite positives.
 

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2TurnersNotEnough said:
One of the reasons that the tapered HT is becoming more popular with manufacturers is to help deal with the flex in the crown-steerer tube interface under braking. Hopefully Turner will go that direction with the 2011 Sultan.
yes, i agree - tapered headtubes are a bigger advance than either disc brakes or suspension in general
 

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Discussion Starter · #8 · (Edited)
True the BB was low, especially with 180mm cranks, found that out quick. Any good word on the WB 135?

I dont think what I experienced was head tube related. If I was slow speed braking and turning sharp the forks would flex forward and aft in line with my stem, so basically at whatever degree I pointed them at if that makes sense.

I am not gonna worry too much about it, as I am pretty much sold on the bike, I just want the stiffest forks available.
 

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dirtydoug said:
Anyways as far as front forks go I have been extremely happy with my Maverick duc32. Granted shorting my self 0.1" travel compared to rear end. 4lbs., dual crown, and 24mm axle are some definite positives.
I have a lonely DUC32 in my garage that I was considering for a 29er, but the problem is that the A-C is even shorter than a Fox F29 120 (which is the shortest 120mm SC fork). I'd prefer to go longer on the Sultan, since the HA is a bit steep, and BB is low, for my taste (especially compared to my over-forked 26er). The light weight and stiffness is nice, but I wouldn't recommend it as a heavy duty fork for a 200+ lb rider.

I'm considering the Marz 140 and the WB 135, but will likely stick with the known good quality of the F29 or Reba (also because Push works on them).
 

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Dawgwalker
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Don't discount that some of that flex may be the wheels. Tension is more important in 29 wheels IMO and building with an adequate number of spokes 32 X3 optimum.
 

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RipRoar said:
Any good word on the WB 135?
I really like mine on my Lunchbox; I'm about 195 all geared up and haven't felt any fore-aft flex in the fork. The 20mm bolt-on (non QR) axle is a good match with the 150mm spaced 12mm Maxle in the rear. I know they were working on a larger-stantion (36mm maybe?) version too; may be worth an e-mail to White Bros. to see where they're at with that.
 

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RipRoar said:
The Sultan was equipped with Team Reba forks and Magura Marta brakes. In low speed braking the forks would chatter forward and aft from what appeared to be the way the brakes were grabbing the rotor. Brakes worked awesome when you had some speed but strange feel in slower speed technical sections. The fork forward and aft flex just didnt seem like a good thing. Anyone follow me on this?
i'm on a 2007sultan v1 with a Reba from the same year. everybody was talking about how flexy the earlier Reba forks are (i guess side to side flex) as compared to the 2009/2010 models, but what i experience is exactly what you describe, for and aft movement that causes the whole head tube area to vibrate under chatter/rocky conditions. going through the chatter, i can look at my friends fox 36 fork on a long travel 26" bike and i see nearly no head tube vibration and his fork is sucking it all up. i thought it may have to do with head angle as the sultan v1 is 71 degrees (i think ) and his 26" bike has a better "angle of attack" at 67 degrees. i also thought it may have to do with the fact that my 2007 Reba is an older model before changing offset and the improvements in stiffness. now i am really confused as i wanted to change out my "whimpier" reba for the Team Reba 120 with maxle or the Fox 120 fork. if i'm not going to see a great improvement in for to aft movement in the fork, what's the point of putting out a grand (for the fork and the new hub/wheel) for a new fork? (FYI i am 200 lbs and the front wheel is Flow/XT hub/32 spokes).
 

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Two points -

If you're running rotors that are more holes than material - they are prone to the low speed shuddering that you describe. I run Alligator Cirrus rotors on my clown bike, and it does exactly what you describe. Putting proper rotors on will go a long way to fixing the shudder.

Secondly thru axle/15QR won't make squat of difference for fore/aft deflection. Fat axles improve resistance to shear and torsional forces. Triple clamps, reduced travel and fatter stanchions are the way to increased rigidity in the fore/aft plane.
 

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abevern said:
Two points -

If you're running rotors that are more holes than material - they are prone to the low speed shuddering that you describe. I run Alligator Cirrus rotors on my clown bike, and it does exactly what you describe. Putting proper rotors on will go a long way to fixing the shudder.
Good point. Marta rotors are, shall we say, minimalist. I run Louise brakes/rotors on my DW Sultan and can't say I have any issues.
 

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2TurnersNotEnough said:
Good point. Marta rotors are, shall we say, minimalist. I run Louise brakes/rotors on my DW Sultan and can't say I have any issues.
but do you have the aforementioned "for/aft" movement of the fork transmitting vibration into the head tube area? thanx!
 

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abevern said:
Secondly thru axle/15QR won't make squat of difference for fore/aft deflection. Fat axles improve resistance to shear and torsional forces. Triple clamps, reduced travel and fatter stanchions are the way to increased rigidity in the fore/aft plane.
By shear, I assume you mean lateral (out of the wheel plane) forces, and by triple clamps, you mean dual-crown (I would say all boingy forks have a lower triple clamp, although they're typically bonded). I'd also add tapered or 1.5 steerer tubes to your list; very effective when you realize that the maximum bending moment is at the lower head bearing. Unfortunately, you can't just fit one to your existing frame.
 

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Discussion Starter · #18 ·
Well I guess it is good to see my experience being verified. I am mechanical enough to realize it was mostly caused by the brakes (slow speed) but was concerned that it created so much chattering in the fork, hence all my fork related questioning.

I just don't see how the wheel set would have anything to do with that type of flexing as well as the axle. The way I see it, in fore/aft flex it comes down to either fork stiffness or head tube flex but I ruled out the head as it would happen while turning.

In my case triple clamp meant dual crown triple clamps, as in e'hem, Monster T. I know, I know but its been a fun 10 years of riding my over forked 26er's believe me! I guess I am so used to absolutely no flex what I experienced seemed crazy flexy (fore/aft only).

Adrian
 
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