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Bike handling not quite right

1K views 22 replies 15 participants last post by  BontyRider 
#1 ·
Ever since I built up my Kelly I've felt that something's just not quite right with the way it handles. Something is "off" with the geometry of the frame, the handlebar, the crank, or *something*. I'm really not good at diagnosing this sort of thing, so I'm wondering if anyone might have some ideas...

Two typical times I notice it:
- If I'm climbing and have to make a sharp turn (i.e. switchback), I feel very unstable (steering-wise and balance-wise) and often step off.

- Coming through sandy turns, it constantly feels like the bike is oversteering. Front wheel likes to wash out a lot, or at least threaten to wash out.

- Steering through rock gardens, I get this truck driver feeling, as if the handlebars are way too wide and I have difficulty pointing the bike exactly where I want it to go. Instead of feeling like I'm locked in down low, I feel like I'm high up, leaning back, and the front end's just kinda bouncing around.

I've checked the pressure in the fork and it's set for my weight, but I DO have a Fox F100RLT on a frame supposedly designed for an 80mm fork (What I don't know is whether the F100 is actually *taller* than the F80).

Maybe the handlebar is too wide for me? (I'm 5' 7" using a big wide Easton EC90 handlebar) Or it's too high? Maybe I should put a flat bar back on there.

Or, the frame geometry is just wrong. The TT is maybe an inch longer than my last frame, but I thought that would add to the lean-mean feeling instead of the truck-driver feeling. Then again if the whole thing is too *long*, that might explain why it feels so NON-nimble.

Oy vey! Here's a pic of the bike BTW (steering tube has since been chopped... and I've peeled off every sticker)

Thanks y'all
-BontyRider
 

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#4 ·
Padre said:
I agree. Fork too tall for the frame.

Try setting things up at the opposite end of the spectrum and adjust back from there.
I suspected as much! Just out of curiosity, happen to know if the F80 is really 20mm shorter dropout-to-crown than the F100, or is the difference internal? Someone told me they're the same externally. (Doesn't seem to be on Fox's website) My handlebar has about that much rise...

Thanks,
BR
 
#5 ·
i'm not sure on the exact measurements, but the 100mm is definately longer then the 80mm. Around 19mm or something?

The good news is that if you take your bike to a competant mechanic, they can change your 100mm fork, into 80mm in about 45mins (or less), and not too much money:)
 
#6 ·
bike_freak said:
i'm not sure on the exact measurements, but the 100mm is definately longer then the 80mm. Around 19mm or something?

The good news is that if you take your bike to a competant mechanic, they can change your 100mm fork, into 80mm in about 45mins (or less), and not too much money:)
That's very, very interesting. I'm guessing it's some sort of bushing replacement procedure. Ok looks like I've got my Saturday afternoon planned. :D
 
#7 ·
it's your bike so do as you please but i would hesitate to modify a very nice fork without trying a few other things first. i have switched a number of frames from 80mm to 100mm simply b/c i find 80mm travel only slightly better than useless...

try a shorter stem (to compensate for TT) and if you can, try a lower stem as well. if this isn't possible try to sweep the bars back and down to accomplish the same thing, temporarly.
 
#8 ·
I've got a F100 that I used to switch between bikes, and I would just add a spacer to the air spring side to go 80mm and that was it. That takes around 20 minutes with beer breaks. It's a special spacer, if you don't have it call Fox they'll send you one.

The fork really is that much taller in 100mm mode, and will throw off handling a tad. I tried it on my 1x1 in 100mm mode and it felt off on the flats. Climbing wasn't so bad, going downhill on the other hand was way faster.

I don't know if it's the perspective or what, but your bike looks quite choppered out, I don't recall my Surly having that much rake.

Maurice
 
#10 ·
That for definately looks too tall for the frame, as others have said.The only real way to tell is to either convert the fork, or put a shorter one on temporarily. Any other fix will not give you an accurate feel. Putting more sag in the fork would help some, but on the uphills when the fork is unweighted, the front end will still come up too high. And lowering the handlebar will not work either, as it will lower the bar, but the head angle will stay too slack.

I am very familiar with the feeling you have on that bike. I would describe it as the front wheel feeling "floppy" when negotiating uphill technical sections slowly. On the other hand, when you come down the other side and the speeds go up, the bike should feel very stable!
 
#11 ·
just ride it...

As long as you're not worried about damaging the frame by running a fork that is too tall, I would just ride the bike.

I have had a couple of bikes that were pretty chopped out, which your kelly sure is, and I found that at first I was really bugged by the handling differences, but I soon got used to the ride. For me the advantage of having more suspension travel was worth the extra time to get used to the bike.

I used to ride my 1992 non-suspension corrected paramout frame around with an 85 mm fork. Felt funky at first, but the suspension fork was soo nice.

As a note: if you wanna quicken things up a little, go to a longer stem not a shorter stem.
 
#12 ·
chuffer said:
As long as you're not worried about damaging the frame by running a fork that is too tall, I would just ride the bike.

I have had a couple of bikes that were pretty chopped out, which your kelly sure is, and I found that at first I was really bugged by the handling differences, but I soon got used to the ride. For me the advantage of having more suspension travel was worth the extra time to get used to the bike.
QUOTE]

If I had another bike I'd definitely be more likely to just leave it, but I've just never gotten used to it. It's starting to sound like it was a bad idea to put that big fork on there! Hm, maybe it's time to go (back to) fully rigid! :D
 
#13 ·
Fork's too tall. That is my initial, gut reaction based on your info and pics.

If the frame is designed around an 80mm fork (axle to crown height) and you have added 20mm, there's your first target to correct. I would think the extra height is even more exaggerated on a smaller frame than a larger frame, due to slackening the angles more.

You should have a bike that rides so you are comfortable and happy. Don't just accept it because you built it a certain way. I wouldn't be happy stepping off in switchbacks I know I could be riding... Good luck and let us know how it works out.

:D GG
 
#14 ·
OneGearGuy said:
Fork's too tall. That is my initial, gut reaction based on your info and pics.

If the frame is designed around an 80mm fork (axle to crown height) and you have added 20mm, there's your first target to correct. I would think the extra height is even more exaggerated on a smaller frame than a larger frame, due to slackening the angles more.

You should have a bike that rides so you are comfortable and happy. Don't just accept it because you built it a certain way. I wouldn't be happy stepping off in switchbacks I know I could be riding... Good luck and let us know how it works out.

:D GG
Thanks. I guess I'm leaning towards throwing an inexpensive rigid fork on there for a while as an experiment to see if I want to put the Fox under the knife. The Surly 1x1 is purty.... (=
 
#15 ·
"Trail" is too great...

BontyRider said:
...I'm leaning towards throwing an inexpensive rigid fork on there for a while as an experiment...(=
Good call! I did exactly that with a Moots YBB that I had. It was old enough to have been designed around a 63mm travel fork and even an 80 mm travel fork changed the handling for the worse. What's happening is you are decreasing your head angle and as a consequence you have increased the "trail" of the bike -- slow handling, washing out, etc.

My experiment with the Moots was a rousing success and by bringing the trail measurement back to where it was designed helped a ton. I subsequently had a custom frame and fork built with the trail dialed in to a point that works best for me.
 
#18 ·
fork heights

BontyRider said:
I suspected as much! Just out of curiosity, happen to know if the F80 is really 20mm shorter dropout-to-crown than the F100, or is the difference internal? Someone told me they're the same externally. (Doesn't seem to be on Fox's website) My handlebar has about that much rise...

Thanks,
BR

...the More travel - the TALLER the Fork is physically - every frames' geometry specs have a fork height spec'd too - change the spec'd FORK height and you change your frames' geometry (headtube angle) - which would affect handling for SURE ...check with your manufacturer, chances are your Hardtail frame IS spec'd for an 80mm MAXIMUM fork - so your 100mm Fork may just be too tall.
 
#19 ·
Followup: What a difference 20mm can make

(Um, that didn't sound right... moving on...)

I had a fellow at my LBS take my Fox F100RLT under the knife to reduce the travel down to 80mm.

Either my imagination is playing tricks on me, or that bike rides WAAAAAY better! Thanks to everyone who pointed out that the fork was just too tall. The bike is *great* now. It is, as they say, DIALED.

I took it on the same trail I rode just before I had the conversion done, and the difference is remarkable. It felt grippy and stable through the sandy corners, didn't oversteer or threaten to wash out, and all those ascending swtichbacks were suddely nothing to even think about. I did bottom it out several times, but I haven't tweaked the pressure yet.

*Finally* the bike rides like I was hoping it would. Sweet.
Thanks everyone.
 
#20 ·
can you post another pic...

with the adjusted fork. I feel like I am having some of the same problems with a new frame I purchased. Yet, I was under the impression that the spacer would only change the compression distance and not the external height (chek out the manual if you have one). I feel like my TT is a bit too short and the front end is too high with the F100X up front. I wanted to put an F80X and drop the front end hoping it would give me a more XC feel without trying to mess with the stem and handlebars or the seatpost. thanks, CK
 

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#21 · (Edited)
cavitykilla said:
with the adjusted fork. I feel like I am having some of the same problems with a new frame I purchased. Yet, I was under the impression that the spacer would only change the compression distance and not the external height (chek out the manual if you have one). I feel like my TT is a bit too short and the front end is too high with the F100X up front. I wanted to put an F80X and drop the front end hoping it would give me a more XC feel without trying to mess with the stem and handlebars or the seatpost. thanks, CK
Ok what I SHOULD have done was actually MEASURE the dropout-to-crown distance before and after the conversion. Thought of that a tad too late. :rolleyes:

There is definitely a 20mm difference between the F100 and F80 (duh). But as for the conversion, as I said before, it sure SEEMS different, but I've got no empirical data. Sigh.

Anyway, here's an "after" pic of the bike. I'm pretty darn sure that the chainstays are more level than they used to be, and it seems to look less chopped in general.

EDIT: A quote from Fox:
"Yes, our crown to axle height does change between different travel settings.
The 100mm will have a distance of 470mm and the 80 will have 450mm.
The F100RLT can be adjusted down to 80mm."

Well I'll be.
 

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