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Struggling to get my 2013 Trek Superfly FS set up perfectly. I have the 70mm stem flipped which gives a good climbing and riding position, and really doesn't seem all that low, and doesn't feel long either - if anything, slightly on the short side. But 90mm stem feels ungainly.
So the bike is great until I come to twisty bits, then I feel like my weight is too far over the front. I think it's because the frame is probably a little on the short side. So the question is, is it worth trying an Angleset/slackerizer?
It's an XC bike, surely you want it weighted over the front on twisty bits?
dragon - Member
It's an XC bike, surely you want it weighted over the front on twisty bits?
As above. If anything when I read the first half of your post I was thinking 80mm stem.
Have you tried the 70mm flipped the other way? (I'm thinking you mean you have it flipped down atm)
It's an XC bike, surely you want it weighted over the front on twisty bits?
No, too much weight over the front makes it hard to change direction quickly because the front tyre is working hard. You and the bike pivot around the contact patch of the rear wheel, so the closer your centre of mass is to that point the faster your bike can change direction. It's why they bend seat tubes to tuck the rear wheel under on some bikes.
You only want weight over the front to keep the tyre gripping in long fast corners. Short sharp slow ones you want your weight back.
If I flip the stem to a positive rise, I'm sitting too upright on climbs.
Try another 70mm stem with less rise?
Point is I don't want the bars higher.
What's the angle of the stem you've got -/+?
Any spacers you can put on top off the stem rather then under?
Does it feel like the bike wants to tuck in the twisty descents?
Slackening the head angle would pull some weight off the front wheel, but it'll reduce the reach also, so if the frame is a little too small it may make you feel more cramped. It'll be a minor difference, but it will be shorter.
What's the offset on the fork? A shorter offset may help by increasing trail. Which would help with tuck, if that's the problem.
I guess the other question is, how often do you ride your XC bike? And do you ride a long and slack bike most of the time?
Yes it's tucking under.
What's the offset on the fork?
Aaaaahh.. yeah this might be the issue.. It's a Trek innit and has G2 geometry so they come with forks with different offset don't they? Is it more or less I can't remember. I only have normal Rebas.
Bugger. Haven't the cash for new forks.
so they come with forks with different offset don't they?
Usually 51mm iirc.
So it seems they have MORE offset to create less trail. Hmm. The only thing I can change is the head angle isn't it? But it would have to be steeper to reduce the trail. That might help with the reach but could cause other issue with the handling.
Might as well get an angleset, see what I can do. £50 at superstar.
51mm offset is pretty much standard for 29ers, so it's probably not that.
My money's on the frame just being too short, but a slackset would probably help if you're determined to keep it.
£50
Put it toward a new correctly sized frame/bike with a 68.5 HA.
I'm selling a large Boardman Pro 29er triple butted alu HT frame with a 68.5 HA, if you wanna take Kryton's superb advice.
😉
FFS, the whole point of spending small amounts of money to fix things is because I haven't got large amounts of money for new frames.
You may all be swimming in cash, but not everyone is.
You cant polish a turd... Etc
Just put all of those little bits of money away. It all adds up.
Thanks for that wisdom. I had no idea lots of small amounts of money added up into a large amount.
So in the intervening five years, I should just put up with it. Thanks for that contribution, that really gives me insight into trail, head angle and tucking under.
You can't polish a turd, but this isn't a turd it's a bike, and bikes can be adjusted and tweaked. Hence the thread.
Offset bushings are cheaper
Sorry molgrips, i appreciate my quip isnt helpful in the way you want ot to be. But i have been down the wrong sized frame route and now i have the right size / geo the feel is amazingly different. Im merely suggesting if its wrong, itll always be wrong no matter waht you add to it. Probably.
As discussd, perhaps try an offset headset or rear shock bushings. If the back is short or to move your weight backward what about a layback seat post? Or it could be technique - drop your heels, lean back and take the weight off the front when cornering?
Offset shock bushings.. interesting, hadn't thought of that. Seatpost is already laid back and saddle rearwards.
Leaning back is already part of the deal but with the saddle where it is, there's not a lot of scope. A dropper would probably help, but in some ways I don't want to be pressing buttons all the time on every up and down.
I can just put up with it, but it's a shame to have to slow down on corners. I suspect that getting a 51mm offset fork might help but that's not easy to do on the cheap.
Leave the 90mm stem on for a month.
I reckon it's more down to your position on the bike while riding said twisty trails, try (although you may already be doing so) getting you're backside lower and realxing the grip a tad, and lean you not the bike so the grippy bit of the tyre is doing the work and the whole thing is more upright and therefore stable. Might work, might chuck you into a tree 😆
The saddle prevents me from getting my backside lower. I'm normally pretty good at these kinds of trails, this bike definitely makes me feel less secure doing these things. And the fact it was designed around a different fork offset suggests it's not working optimally.
I think what you are describing is potentially a Trek 29er trait. I have a Trek 29er with G2 and it isn't great in slow twisty stuff, you just have to man handle them through as best as you can. But on fast stuff they are freaking awesome. I bloody love mine, and like all bikes, cars etc. setup is about balancing different requirements, and personally I can put up with average through slow twisty stuff, for blooming fast everywhere else.
My question is how have you potentially ended up with too small a frame with the wrong fork offset? Mind even with the wrong offset it shouldn't be horrific.
It's not horrific, really. Just a bit of a tendency, which annoys me somewhat. And you are right about balance. I can improve it by raising the stem, but then it feels less good putting power down. I can also get used to it and learn to work with it. Balance is one of the things I appreciate in a bike though, and it's a little frustrating. Although to be honest, this particular piece of trail might be highlighting this trait - I could take it further afield.
I bought the frame as an excellent bargain s/h from here, it seemed big enough but it's rather difficult to tell when it's not built. There's no size sticker on it. And the fork was one I already had that seemed suitable.
I could simply save up and wait for a new fork to present itself s/h, but the Slackerizer idea intrigues but so do the fork bushings. Geometry feels a bit better with more sag in the shock but then it is too soft, so that might address it.
Built up a Superfly recently, geometry optimised for 51mm offset. Thought about spending money I didnt have on new forks too, but decided to just lump the old Fox 32s on and it rides fine. I might opt for 51mm offset SIDs or reba sometime in the future, but only because the white fox forks look terrible on a black frame with black wheels and black decals, and I only have crown lockout which I keep forgetting about mid race.
Its an XC race 29er. Its made for going real fast up climbs and on flat straights, you are over thinking it on technical descent stuff. Adapt to ride the stuff on a less forgiving bike and accept it just won't feel as capable as a more trail bike kind of set up.
you are over thinking it on technical descent stuff
I whole heartedly disagree. XC racing involves going fast down and along as well as up. XC race courses aren't usually that steep (but sometimes) but twisty single track features heavily. Also, my previous XC race bike flew on the climbs and was also extremely quick on the singletrack.
Well I raised the stem by 10mm but kept it flipped. Felt too high at first, but actually got used to it quite quickly and it made all the difference. Much better. Raised the saddle about 5mm and it was better for power too. And the bar width felt much better too.
Moral of the story - even 10mm makes a difference, so make sure you've thought about your bike and tweaked it before you change it for something else, you bike tarts 🙂
Now just need to decide if I want wiggly bars or not.
Recently put an angleset on a canyon xc hardtail. Head angle reduced by around 1.5 degrees. Feels good so far.
If you feel that the geometry feels better with the shock soft but it's mushy, then offset bushings would definitely work, clearances permuting. I have an older 100mm fs with too high a bottom bracket so I put one bushing in and the improvement cornering and descending is massive, I'm thinking of going for a second offset bushing to lower / slacken even more.
It's a really cheap fix and easy to swap out if you don't like it, you'd get to run the shock firmer but with more hunkered down geometry, one bushing only costs between 10 and 20 quid, depending on supplier. My bike is too short for me as well and this mod has bought it back to life, Sitting lower in the bike gives a feeling of the bike being longer in my experience and I'm certainly riding it a lot more.
Hmmm. By coincidence my Anthem needs a new shock bushing. At 70 degrees I guess I could get 69 easily?
Link to a good shop?
@inkster that's for that, good to know. Cheaper fix than the angle set. Will try it out at some point.
There is no bushing on the lower eyelet of an anthem (shares lower link pivot) so you can only fit one.You'll get half a degree if you're lucky (less if it's an 8mm shock bolt).
Indeed,I was just reading up on it.
If I have to replace the bush anyway I may as well give it a go though, £12 is a cheap way to lose even 1/2 a degree.
Had similar issues with my old bike, this over the front feeling is not at all pleasant. Fannied around with stems/ bars/ forks/ spacers for ages until I admitted what I knew in the first place, that the frame was just too small. Try having a shot on a similar larger bike if you can.
You cant polish a turd... Etc
Right, well Kryton57 was dead wrong.
Got hold of some 51mm offset forks. They are better than the Rebas as forks (Fox F32), slightly shorter A2C too. But the bike is completely different in corners. Really solid, stable and planted, I can feel the front hooking up really well. And it's really nippy in the twisty bits.
Also fitted a slightly wider riser bar which has helped the riding position - I may cut that back down again.
So to all of you who're ready to write the bike off with 'oh it's only an XC bike they always handle shite' - not true. This one's brilliant now it's set up properly.
Well, I’m pleased to have been found wrong. Glad its worked out for you.
Nice one.
Congratulations , you must be one of the elite few who can notice the difference that changing fork offset by 5mm makes .
Anyone prepared to leave the bike over would have noticed. Huge difference. Nothing to do with being elite, just need to lean it over.
My solution was going to be bar ends. So that you could have less reach in the twists but a stretch up hill
Glad you are sorted. It's good to be reminded that it is worth persevering with setup
Also fitted a slightly wider riser bar which has helped the riding position - I may cut that back down again.
Why think about cutting them down if they help the riding position .
Congratulations , you must be one of the elite few who can notice the difference that changing fork offset by 5mm makes
It has the same effect on trail as just under 1 degree on the head angle and people obsess about that enough for anglesets to exist.
But moving from 46mm offset to 51 mm offset should have exactly the opposite effect to what he is claiming it to have .
Bit of a tangent, but I just listened to this podcast yesterday, Cesar's got some very interesting thoughts about XC bike geometry...
http://www.vitalmtb.com/features/The-Inside-Line-Podcast-Cesar-Rojo-Founder-of-UNNO-and-Cero-Design,2045
It covers head angles, BTW.
Got hold of some 51mm offset forks. They are better than the Rebas as forks (Fox F32), slightly shorter A2C too. But the bike is completely different in corners. Really solid, stable and planted, I can feel the front hooking up really well. And it's really nippy in the twisty bits.
I could definately tell the difference between my dads 42/44mm offset Lyriks and my 46mm Pikes. They do have less of a tendency to tuck under. I find higher offsets more reactive and more forgiving when weighting up the front too much.
Giant went back to 46mm offset Lyriks on the 2018 Reign, after running 46mm offset Pikes on the 2015 and 42mm offset Lyriks on Lyriks on the 2016 and 2017.
The complete opposite to Mojo and Transition.
But moving from 46mm offset to 51 mm offset should have exactly the opposite effect to what he is claiming it to have .
Maybe, depends how we describe things perhaps. My 29er has a long offset fork (55mm) and lower trail than most MTBs by 25% or more yet it's very stable, corners beautifully. It's just not the slack/floppy kind of stable. Trail, weight distribution and HA-offset combo are a 3-way thing that can be balanced up more ways than I can get my head around.
But as far as effect, 5mm change on offset isn't hard to spot if you're in tune with the bike, whether it matters or not is another Q.
I could definately tell the difference between my dads 42/44mm offset Lyriks and my 46mm Pikes. They do have less of a tendency to tuck under. I find higher offsets more reactive and more forgiving when weighting up the front too much.
A higher offset and slacker HTA seem to avoid some of the tuck-under tendancy, probably by achieving a given trail figure with a less vertical steering system. Same trail figure from a steep HTA and less offset is less carvy, easier to overweight or over-lean, if that makes sense. Mostly to do with weight distribution, or front weight/loading as you say.
/geek : )
But moving from 46mm offset to 51 mm offset should have exactly the opposite effect to what he is claiming it to have .
What makes you say that?
The front wheel is now further away from me, so it's a bit like having a slacker Ha in that respect. Trek seem to have specified a steeper actual HA whilst relying on the increased offset to stop it feeling nervous.
I think the riser bar has definitely helped the overall handling. Previous setup was flat 695mm bar with a 70mm stem flipped. That was probably the wrong choice too. But the big difference is in the feedback when I start to turn and when I am leaning over. There is push back from the front tyre, it feels secure and solid. Whereas before I'd lean over and the front wouldn't push back which is why it felt insecure, vague and made me nervous.
Why think about cutting them down if they help the riding position
They'd still be risers.
Today though I put the saddle forward 5mm or so and the width felt easier to deal with so maybe I'll stick with it a while.
It's good to be reminded that it is worth persevering with setup
This... I think a lot of people get rid of bikes because they aren't 'right' when really buying a bike may be only the start of the process of getting it right.
Same trail figure from a steep HTA and less offset is less carvy, easier to overweight or over-lean,
That's how it felt. HA is something like 71 degrees which is why I think it needed the 51mm offset.
This brings and interesting comparison with my Anthem which feels much more stable at 69.25 degress eather than 71 static.
You fitted an angleset? Or the bushings?
The front wheel is now further away from me, so it's a bit like having a slacker Ha in that respect. Trek seem to have specified a steeper actual HA whilst relying on the increased offset to stop it feeling nervous.
What you are describing is precisely the effect Trek (and Gary Fisher before Trek) meant to achieve with the G2 geometry.
It is nicely illustrated here:
[url= http://http://blog.artscyclery.com/ask-a-mechanic/ask-a-mechanic-29er-forks-46mm-or-51mm-offset/ ]null
Good article Ramsey but it's coming at it from a slightly different point of view. He seems to be talking about choosing offset to get a particular characteristic. However Trek designed the rest of the package to take advantage of the extra offset, so it would seem that reducing it moves the steering forces into something undesirable - for me at least. Without it, it's too steep to be good imo.
It's not a new thing for Trek/Fisher anyway, nor is it a 29er thing - I had a 2004 26" bike with Genesis geometry and apparently it goes back to '99.
You fitted an angleset? Or the bushings
A 120mm for for -1 and a single offset bushing in the rear shock for -.75
Interestingly less trail seems to be the way it's going on modern 29ers , I find it all very confusing . I am 6ft tall and have a 19.5 Superfly FS and use it as a race bike although hip surgery has meant no racing for me this season . I think I have a 90mm Hope stem not slammed with a 700mm flat bar and it seems fine on the ups and downs and the nadgery bits inbetween I am certainly not a riding god though and tend to just jump on a bike and adapt to how it is rather than try to change stuff . Glad it's worked out for you .
So what we've learnt is that if you have a bike designed for a specific fork offset, then it rides better with that fork and not one which it wasn't designed around. Earth shattering 🙄
It's not like Gary Fisher and Trek haven't had years designing these things. The original Superfly was one of the bikes that convinced the masses that 29ers were the future. That bike blew up big time in the USA and was the hottest bike for a season, everyone wanted one and that really kick started things over the pond.
What a pleasant kind post dragon.
Yes, we've learned that it matters. There are a lot of posts on the internet saying 'can I use a G2 frame with a normal fork?' and a lot of peopel say that it won't matter, as 5mm isn't significant. And a lot of people wondering how much it matters.
Well, I think I've answered that, for myself at least. It does matter, quite a bit.
it seems fine on the ups and downs and the nadgery bits inbetween
If you bought the bike complete you'll already have the right offset fork.
I'm not surprised you can feel a 5mm change in fork offset. One of my bikes has adjustable geometry via moving the dropouts, so the slacker setting drops the BB by 6mm and takes half a degree off the angles. Totally changes the feel of the bike.
Some people just don't notice this stuff though - lucky sods! 😉
Interestingly less trail seems to be the way it's going on modern 29ers , I find it all very confusing . I am 6ft tall and have a 19.5 Superfly FS and use it as a race bike although hip surgery has meant no racing for me this season . I think I have a 90mm Hope stem not slammed with a 700mm flat bar and it seems fine on the ups and downs and the nadgery bits inbetween I am certainly not a riding god though and tend to just jump on a bike and adapt to how it is rather than try to change stuff . Glad it's worked out for you .
There's two debating schools of thought, one the one had some companies like Transition and Mojo are going with shorter offsets - others are going with Longer - eg Giant.
I think it has a lot to do with your style of riding, I use countersteering a lot and tend to weight the front of the bike quite heavily in steep switchbacks, that's where longer offsets feel particularly good to me.
I'm not surprised you can feel a 5mm change in fork offset. One of my bikes has adjustable geometry via moving the dropouts, so the slacker setting drops the BB by 6mm and takes half a degree off the angles. Totally changes the feel of the bike.
I've found that out of half decent riders - there are two general types - those who would be suited to racing who will go fast whatever. And those who would be good at development riding/driving etc - who are more analytical. The rare unicorns, are people like Valentino Rossi - who is both.
some companies like Transition and Mojo are going with shorter offsets - others are going with Longer - eg Giant.
What is different about the rest of the bike though?
As for fast riders being fast - of course, but if there was something really not right about a bike they would call it out.
The flip side to my previous post I have a Trek Remedy 29er from 2014 which has had the original Fox 34 fork with a 51mm offset 140mm travel which I swapped for a 150mm travel Yari with a 46mm offset . Other than the Yari being way better than the Fox in terms of suspension performance I have noticed no noticeable difference in the handling but as I said before I don't tend to be able to notice small differences .
But with a longer fork and slacker angles it may have remained within a range of workable parameters. Maybe mine, being step to begin with, the offset had more effect. Plus you fitted a longer fork which would also move the front wheel away from you, so reducing the offset might've been a good move in your case.
As for fast riders being fast - of course, but if there was something really not right about a bike they would call it out
Not suggesting Im fast but:
Yep. When i bought my Race HT it came with a 69 degree HA. I knew immediately I was more comforfotable with it than the Anthem, and since then have replicated every facet of its measurements that I can with positive results.
Before then, I’d have put myself in Neils camp of not really feeling small changes. But now the Anthem setup has changed its noticable on the trail. One conundrum remains though; obviously I cant change the changestay length, but the HA changes and the lower BB resulting from the offset bushing make it [i]feel[/i] as though they are shorter, and I dont understand the physics of that yet.
make it feel as though they are shorter, and I dont understand the physics of that yet.
You've possibly made the bike better-balanced by lengthening the front end.
My new bike has 455mm chainstays and 460mm reach. The rear end doesn't [i]feel [/i]any longer than my HT which is about 445mm/435mm (and longer stem).
I dont understand the physics of that yet.
Well my suggestion would be as follows:
When you turn a corner, you and the bike are pivoting around the contact patch of the rear wheel (in your moving frame of reference). The force to make you pivot comes from the front wheel contact patch. So the closer your centre of mass is to the rear wheel AND/OR the further the front wheel is from the CoM, the more leverage the front tyre has so the more easily it can pivot.
Shorter chainstays move the rear wheel closer to your CoM; raising your bars makes you sit up more which moves your CoM closer to the rear wheel, as does shortening the stem. Slackening the seat angle does the same thing. Longer forks, more trail or a slacker HA increase the leverage the front tyre has on your CoM.
I have found in the past that moving the saddle backwards and shortening the stem (or even rotating riser bars) can move your whole CoM backwards and change the manoeuvrability.
You seem to be talking about rotating the bike there chaka, rather than railing the corner. Surely if there is no weight over the front at all, the front wheel will slide out, as in order to rotate the bike you have to overcome some angular inertia (there is still mass to move, even if no weight over the front).
It's got to be about getting the front/rear balance right, and probably there is a cornering technique to suit different points over a range of weight distributions.
You seem to be talking about rotating the bike there chaka, rather than railing the corner.
The bike has to rotate in order for it to end up pointing in a different direction. The closer your CoM is to the back wheel the less force is required. So even if you have less weight on the front, you need less. In my experience, very twisty trails like say Seagull in Swinley are much easier with your weight over the back - usua\lly. If it's really muddy or slippery, then traction can be an issue.
That applies to twisty tight corners. For longer fast corners you need much more force to change direction, so you need to balance the weight on both wheels which means moving forward a bit. The bike is only pivoting slowly.
I agree up to a point. But in the absence of any data or (very difficult) calculations, we can't make any progress with this as we need to know how significant the forces are when comparing the need to initiate and then cancel some rotation with the need to provide some cornering force. Also, most of us probably use a fair bit of body movement to momentarily rotate the bike under us (I have always thought this was particularly important with a weight-rearward style) so it isn't just the front tyre that provides that.
Or we could just use our experience. Honest question - have you ever ridden Seagull? It's an extreme test case, because it's a smooth narrow surfaced trail that is just a series of narrow radius but smooth bends that almost double back on each other, without much if any interconnecting straights. So you really need to think about technique or you'll be slow.
I thought my XC bike was quick handling and my big bike slow handling, so I assumed the XC bike would be better for that trail. But it was much worse. I tried to get my weight foward but that makes it nearly impossible to go fast. Only way to get any speed is to put your weight way back, turn the bars a lot and almost pull the bars around.
EDIT er.. wait.. is it Seagull? Or one of the others? Ergh.. the dead windy one anyway.
I don't come from that way, but it sounds like good woodland fun. Can't think of anything round here (Cardiff) that has the smooths, and that twisty tends to imply steep as well. Are the turns so close that you are straight(er) lining with your upper body as the bike follows the trail?
I'm also in Cardiff. And you're right there isn't much along those lines here.
Are the turns so close that you are straight(er) lining with your upper body as the bike follows the trail?
No, you have to completely change direction on each bend. Quite artifical, natural trails aren't like that.
Since you are from Cardiff, you'll know the trail that promted this whole problem with the bike and fork - the fence line at Castell Coch. With the old fork and bar I just couldn't go at any decent speed down it. Felt terrifying all the way down. I can hit it properly now.
Handlebars and roots down there. I will experiment next time.
Another nice feature of my Spitfire is that in addition to being able to move the dropouts vertically to change the angles and BB height, you can also swap the dropouts for different lengths (and axle standards). As it had acres of mud clearance with the 27.5 dropouts I swapped them for the 26 ones which shortened the chainstay length by 10mm (still running 27.5 wheels).
With the shorter chainstays It flicks into turns noticeably more easily, especially sequences of berms - responds better to subtle hip movements.
Since then I've lengthened the front centre with a -2 deg Works headset so it's over 20mm longer and it's still nicely flicky.
Adjustable geometry is ace. Sliding shock mount on my Patriot made it awesome.