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Not sure what the hells going on but I bought a Giant TCR which comes with 42mm deep aero wheels and the bike wanders all over the place at high speeds or in the slightest side winds.
These are my first pair of "aero" wheels and, frankly, they terrify me. What am I doing wrong?
How heavy are you?
88kg (and 1.93 metres, or 6'4", in case that is relevant...)
42 mm is not massively deep, you may get some disturbance from wind but nothing major.
Are the tyres seated squarely and are the rims true?
Have you ridden road bikes before? If not it may be you are unconsciously tensing up during the quicker descents.
Speed wobble is frightening at high speed.
Not sure about the tyres so I'll check that out but not seen or felt anything odd
Yes, I've ridden multiple road bikes before but none with "deep" rims (granted, mine aren't particularly deep).
My other road bike is a Cannondale SpeedSix with bog standard rim brakes and I would confidently hit 80km/h+ down the local ski hill roads but the Giant is terrifying, even when I consciously relax...
I have a tcr with the slr1 42 mm wheels and it's the most jittery bike I've ever ridden at speed. I'm not sure what you are experiencing is speed wobble as such, rather just the nature of the bike!
For what it's worth mine is super fast, but I far prefer my defy for most of the riding i do..The tcr feels like it's always on edge.
The problem now is overcoming the subconscious fear of descending on this particular bike.
I had this once on a bike I owned and I failed to ever trust it at speed after a couple of out of control speed wobble experiences where the bike shook violently. I stopped riding it because it scared the shit out of me.
Like you I have had multiple road bikes and have been on TT aero bars at 50mph but just could not ride that bloody thing!
The wheels will contribute to a bit of instability, in the wind, but it's more likely down to speed wobble. A friend of mine had it, in his mountain bike, descending from Whinlatter pass to Keswick.
We looked into it, afterwards, and discovered that it can be solved by gripping the top tube between your knees - this changes the resonance of the bike, and stops it wobbling
My old Coventry Eagle developed a speed wobble at around 20 miles an hour. I think it was probably all the off road miles it did before I'm pretty much sure something was misaligned. That shouldn't be a problem with a new carbon frame but it's worth trying with a different set of wheels to rule it out.
OTOH my TCR with 45s feels planted to me, and I weigh 10st
I have 42 and 65 SLRs on my propel.
No such issues.
I can’t see it the wind making it that wobbly. In my experience having ridden all sorts of bikes and deep wheels, the wind isn’t a wobble, it’s more a push. I have 65mm wheels and when going fast downhill, I may feel the front wheel being pushed, multiple ways to compensate for it, but it is a very definite feeling to a wobble.
I also use 40mm wheels as my winter all weather wheelset. In the 20/25mph winds we have recently they get knocked and I can feel the push but it’s really feels different than a wobble.
When my Reynolds wheels were out of true, they would feel like a wobble (front wheel) when going at speed and pulsing when braking (rim brakes).
If you get a real speed wobble try pinching the top tube with your knees it should stop the oscillation. Least it works for me.
Fortunately speed wobble is less common that it used to be - helped a lot by carbon frames which tend to be less flexible along their length. I remember coming down the Wicklow Gap in the pouring rain and nearly not making the big bend due to a viscous wobble. Opinion is its created by a harmonic resonance including the frame, forks, wheels and rider. I changed the forks on my bike at the time and got rid of it.
There's definitely two different sensations at play here:
One is just a slight sideways push at "regular" speeds (eg on the flat) in sidewinds. I was half-expecting that from aero wheels though a little surprised at how "bad" it feels considering the rims are only 42mm. I'm expecting to get used to this and being able to compensate for it. (Although I've had the bike a few months, I haven't been out on it much in windy weather yet).
The second sensation seems like a mixture of speed wobble and aerodynamic instability coming from the front end. I'm having to constantly make slight adjustments and can feel the gyroscopic forces yawing the bike. Next time I'm coming down a big hill, I'll try the "grip top tube with knees" trick.
Your headset adjusted correctly ?
Your headset adjusted correctly ?
Yup, though maybe the stem isn't the exact recommend torque as I don't have a torque wrench and I'm reluctant to over-tighten against a carbon steerer...
Hi, I’ve read all the replies and I’m going to say something a bit different to everyone else.
Not all aero wheels are made equally.
A 42mm aero carbon rim does not equal a 42mm aero carbon rim. Different brands have small differences in the shape to help deal with crosswinds. If you look at Zipp with the tiny holes like a golf ball, Fast Forward which have an indentation under the braking surface and bulge out a bit away from that, and Vision rims which are different again.
I’m not sure what rims are on your bike, but most top end wheelsets can deal with winds pretty well. I have a pair of Vision 40s and a pair of Zipps also (202 on the front and a 303 on the rear... approx 35mm, 45m) both very stable wheelsets.
If you’re confident they are good wheels, then I’m not sure. The bike might have twitchy geometry.... or maybe try a bike fit? Maybe it’s not the bike for you but hate to say that, I haven’t ridden it though.
To the OP, I used to road race on those wheels and their 55mm SLR wheel, certainly no wobble at speed, either descending or flat. In fact the 55mm SLR wheels were pretty awesome.
Are you UK based? Any other wheels you can try on that frame or anyone else try your wheels?
Are you UK based? Any other wheels you can try on that frame or anyone else try your wheels?
Nope, Vancouver...
I have a buddy who wants to buy some aero wheels (so is interested in trying mine) so we should be able to swap them over (same axle sizes and centre-lock discs AFAIK) but that might have to wait til after Covid-19 self-isolation ends...
Speed wobble is frightening. I've never experienced it, but the stories from friends makes me paranoid.
One friend had this issue (different bike/wheels to you) and he fixed it by a combination of removing a spacer under the stem and just going a bit slower. I suspect the latter was more of a fix than the former. Interestingly, he never had issues until he got a pair of 45mm deep Mavic wheels - which suggest speed wobble can be caused by wheels.
When I first got my canyon ultimate I rode it from holyhead to London. Descending down snowdon I got a strange speed wobble. Turned out they hadn't fitted the headset correctly.
May be worth checking stuff like that?
Is your stem long enough?
Is your stem long enough?
I think so.. it's about 120mm I think, not a stubby mountain bike stem!
My fast carbon bike with 55mm wheels sometimes suffers from horrific speed wobble, and yes it can be terrifying. It seems to only occur in certain wind conditions though. I think its more a function of the head angle on the bike. If you have it slammed you could add a few spacers underneath the stem, it seems worse the more aggressive your position. I just dont take it out on windy days.
What bike are you coming off? The TCR is a full on super stiff race bike with race bike geometry so is twitchy. My mates got one, I had a Propel which felt similarly racey and twitchy so responds to every minute movement of the handlebars. Wouldn't describe it as ‘wandering’ or wobbly As it only does what you tell it to do, it’s just super sensitive and super responsive. Have since moved onto a Scott Addict Endurance which is supposed to have a lore relaxed endurance geometry. Well it certainly is a bit less twitchy than the Propel and a much more relaxing and nicer ride though I wouldn’t say it is ‘relaxed’.
I put some 45mm aero rims on the Scott so compared two different wheel sets on the same bike and the deeper rims do respond to side winds slightly more than shallower rims, but nothing particularly alarming or scary and I’ve certainly not had anything that can be described as wobble. In fact at speed they feel more planted, but that could be that they are adjust a better wheel that I came from full stop.
Only ever has this when the wheels were out of true and balance.
Lift the bike off the floor and spin the wheel up by hand - does it want to spin round in a proper circle or does it wobble sideways or in an oval?
Are the wheels built well and fitted tightly? I know it makes no sense but my road bike used to get speed wobbles when descending in the drops and having the front wheel rebuilt cured it. It was true, but the spokes were not very tight.
The reason I mentioned being fitted tightly is that I can't be 100% sure it was the rebuild or simply the act of removing/refitting the wheel which cured it.
Following on from retro83 above, is the bearing preload on the wheels set correctly (if it is adjustable)? I.e. grab the top of the wheel and try to move it side-to-side.
Can you try some different wheels?
See if it's the same or not.
Simple test.
Going back to the headset, it might be worth checking the bolts on the stem move freely in the threads. I had steering issues on my Trek even though they were torqued correctly, turned out the top bolt had a bit of swarf trapped in it so wasn't actually tightening on the steerer. This led to it pushing down on the headset which stopped the micro adjustments and self-correcting you and the bike make.
What bike are you coming off? The TCR is a full on super stiff race bike with race bike geometry so is twitchy. My mates got one, I had a Propel which felt similarly racey and twitchy so responds to every minute movement of the handlebars. Wouldn’t describe it as ‘wandering’ or wobbly As it only does what you tell it to do, it’s just super sensitive and super responsive. Have since moved onto a Scott Addict Endurance which is supposed to have a lore relaxed endurance geometry. Well it certainly is a bit less twitchy than the Propel and a much more relaxing and nicer ride though I wouldn’t say it is ‘relaxed’.
My other road bike (now reduced to turbo trainer duties since I purchased the TCR) is a similarly stiff/racy/responsive Cannondale SpeedSix though is has low end Shimano RS10, shallow rim alloy wheels. I love the "responsiveness" of both bikes but the SpeedSix is a lot more stable on fast descents.
Lift the bike off the floor and spin the wheel up by hand – does it want to spin round in a proper circle or does it wobble sideways or in an oval?
I've just picked the TCR up and held it in my left hand whilst spinning the wheels manually as fast as I can. Both "pulse" noticeably though whether this happens in all wheels, I don't know. I wonder whether they are slightly out of balance (valve or clump of dried tubeless latex inside???). Anyway, both wheels seem true with little side flex and no obvious places where they are out of round.
They are both Giant SLR-1 composite factory wheels so whilst not top end, neither are they cheap Chinese eBay wheels either.
Following on from retro83 above, is the bearing preload on the wheels set correctly (if it is adjustable)? I.e. grab the top of the wheel and try to move it side-to-side.
I believe the hubs are DT Swiss 240 and I don't think they have/need bearing pre-load (ie they aren't cone hubs). Anyway, there isn't any noticable lateral looseness...
Hopefully, I'll get to try another fast descent later today and will report back on whether gripping the top tube with my knees helps!
Update:
I checked out the wheels and slightly tightened the axles (not that they were particularly loose...) then went up the lower part of a local ski hill road. Descending I hit around 65km/h (I was spinning out at that point) and no speed wobble! Granted, it was a windless day and I couldn't get up to the higher speed I can do on the steeper sections...
Another's silly headset question
Carbon steerers have the ally knurled bung in, not a s f. n
These can be fiddly to get right. My lbs guy reckond it was best to tighten the allen bolt with the stem nipped up already. This helps the bung grip the steerer tube.
Try wheel at 90 degrees and front brake on test for movement
I see a 60kmh test was ok, so sounds like the qr s were to blame although i am surprised
I ride a propel with 55mm spins and get the sidevwind push and in a 20kn + crosswind i have to lean the bike to windward and get low on drops, never had speed wobble
Tyre pressure v width could be a factor
Dried latex could be a factor
Pop off the tyres put rims in frame spin them. Up and check for wobble or out of round
my 2p.
I have recently switched from my winter Cannondale CADD4 with open pros and race guards (old school geometry) to my summer TCR advanced. The TCR is noticably lighter and twitchier. The wheels are a lot more sensitive to side winds and speed makes this more evident (and scary). I have found a combination of staying relaxed physically, only making gentle steering corrections and mental alertness works well with this bike. It's not one for a gentle pootle...
Carbon steerers have the ally knurled bung in, not a s f. n
These can be fiddly to get right. My lbs guy reckond it was best to tighten the allen bolt with the stem nipped up already. This helps the bung grip the steerer tube.
I thought the idea of the bung was to compress and load the bearings so there was no play before fitting the stem which holds everything in place, if the stem is done up this won’t work. IIRC You can in theory set up the bung, tighten the stem and then remove the bung - it’s not there to hold everything in place
Yeah if you do the stem up first how will the bung compress anything?
/the outer allen bolt that squashes the 2 parts of the bung together prior to fitting the top cap bolt and tigjtening it down
The theory, and its just a theory is by nipping the stem up you can safely tighten down the 2 parts of the bung witjout fear of splitting the steerer tube. Then remove stem, fit spacers, top cap and tighten down.
Having red it back i failed in my explanation really badly and sound like a dumbo
What tyre pressure are you running?
What tyre pressure are you running?
80psi f&r (tubeless tyres, if that makes a difference)
.
I went out again up a different big hill and "breezy" conditions and, holy f++k, this bike is sooooo unstable it's frightening.
Didn't make any difference whether I was on the drops or the hoods, whether I gripped the top tube with my knees or not, whether I was tense or relaxed or whether I soft pedaled or not (I'm spinning out around 60km/h anyway).
For context, the wobble started kicking in around 55km/h and the bike only stabilized when I braked down to around 50km/h. As soon as I let off the brakes, the wobble kicked in again.
According to Strava, the wind was NNW @ 12 km/h so not exactly blowing a gale. The road surface is pretty good, it's very wide (3 North American lanes wide) and had no traffic whatsoever (it's closed to vehicles currently) and is mostly sheltered by trees. The road is mostly straight with a couple of very wide hairpins.
I've been up and down that road multiple times on my Cannondale previously and never experienced the same problems even on windier days.
https://strava.app.link/h6FBG9hDF5
Strava shows my previous best time on the descent being 65.5km/h (Cannondale) yet I was shitting myself down the same segment at 46.5km/h...🤔
(The KOM is 77.3km/h...😳😳)
It sounds to me like you may be expecting it and subconsciously causing it.
Do you feel yourself tensing up as the speed gets higher?
This happened to me after my experience earlier in the thread and it took me ages to get over it.
Just out of interest, what was the temperature when it happened?
I did loads of reading on the subject when I was going through it and it can happen more when temperatures are cooler because you may shiver slightly when going fast down hill on cold days.
Gripping the crossbar with my knees made no difference at all.
It is incredibly frightening and dangerous when it happens because the bike is out of control, I would veer to left or right whilst braking until the bike was back under control.
Lowest temperature was 9°C at the top of the hill and I had a thermal tee shirt + long sleeve fleece jersey + windproof jacket and whilst I wasn't warm, I don't recall being cold enough to shiver.
Based on the GCN video, I'm wondering whether my frame might be too small...(it's a carbon 2020 Giant TCR so Im confident it's stiff enough.) According to Giant's size charts, I'm slap bang in the middle of the overlap between a L and XL frame and I opted for the L...hmmm.
I've got some spacers under the stem so I might try dropping the front end a little (though not much as my back will suffer).
I went through all of this, changing wheels, stem length and height, saddle height, pretty much everything you read about online I changed. I finally realised that because it had happened twice for no apparent reason I was getting very nervous at high speeds and changing the damping of the bike by tensing slightly.
Took me ages to get over it. Riding my MTB on the road helped, in fact it was doing that that made me realise I was the problem. It was so planted that I was reaching speeds way in excess of what I would even dare on a road bike at that time.
I bought a gravel bike and put 45mm road tyres on at low pressures and gradually improved my confidence.
I can now descend at 45mph+ on 23mm twitchy road bike.
I keep meaning to write an article on what I went through as it may help others.
Just back from a spin on my tcr, which rarely gets used. Today's ride reminded me why...it's not a relaxing ride, and I have to agree with the op, descending is utterly terrifying, it feels ridiculously unstable. Contrast it to my defy, which is a magic carpet ride, and far more relaxing to spend any time on.
I'm not saying the tcr isn't fun, it is, in the same way as riding on the back of a tiger would probably be fun...you just don't want to do it that often ...
Have never ridden a Giant but from comments above not sure I'd want to...the best road bikes are fast, stiff but also have handling which should be rock solid at speed, and they do differ. Given at this time it may be hard to get a bike shop to check it over, I would want to iron out any possibilities that there's something wrong with the bike - check the alignment of the frame, a bike shop will have a tool to do this but you could carefully eyeball the bike from the front and see if the wheels appear to line up perfectly in plane, they don't always and inconsistencies can wreak havoc in high speed handling. Likewise wheel balancing to lesser extent, put the bike in a work stand and spin the wheels at speed - most wheels will have a bit of a wobble even when perfectly true and round due to balancing..wheels where for instance the carbon rims aren't made very consistently in the mould might exhibit a violent wobble in the stand, if you think own brand rims differ much from cheap Chinese options then you may be disappointed. If there's violent wobble in the stand then this is one of many factors that can contribute to speed wobble, I mean like the whole bike bucking in the stand as the wheels spin...really good well balanced wheels are smooth in this scenario, ie: some manufacturers go to the length of weighted inserts to counterbalance the valve stem. A big dried lump of sealant could just about have this kind of effect too.
Some of the comments on the function of the bung in a carbon steerer tube have me slightly worried about the safety of peoples bikes...read the manuals please peoples. No one ever wants their steerer tube to snap at the stem, ever, you do not want to rub your face on tarmac at 40mph. Carbon hates compressive force and the bung is there to support the tube against the forces from the correctly tightened stem...without this set right its tarmac-face Russian roulette.
Strange. I had a tcr for a bit. Rode like a well planted bike. Climbed really well , won me the club hill climb champs on one.
Bought a propel and despite the geometry being more aggressive it's still a delight to ride compared to the stuff of yesteryear.
Fast stiff handles a dream -with one caveat....if you can't ride it fast you won't enjoy it. Its not a bike for bimbling about on. It wants to be ridden fast and it wants to be driven into corners.
If you can't commit you probably do want a more relaxed geometry bike that will forgive you.
My friend had this problem with Giant aero wheels (SLR 0 I think). Will check for the exact cause but I think it was one of the tyres. He got it fixed easily, anyway.
Nudged 80km/h on my TCR in fairly windy conditions on Thursday morning, felt fine. Not entirely convinced it’s the bike tbh
Not entirely convinced it’s the bike tbh
Haha...as the OP, I'm not being self-defensive here but...
My TCR has replaced a similarly racy and stiff Cannondale SpeedSix, though the SpeedSix has cheap Shimano non-aero alloy rims rather than 42mm deep carbon rims. I've been road riding for 20+ years so I'm not a novice and the bikes are comparable. I've even checked the geo charts of both and they are quite close though I doubt the TCR is less stiff than the SpeedSix.
I'm comparing riding the same roads in the same conditions. I've ridden up the same big, wide, open ski hill access roads about 10 times in the last month.
On Thursday evening, there was NO wind and the bike was rock solid (though it still wanders so needs to be brought back into line). Saturday was a little windy and I felt the bike start to shimmy around 55km/h but stabilize once I dropped some speed.
Someone further up this thread suggested gripping the top tube with my knees so I tried that but the TCR has a dropped top tube so that's a bit awkward. I found that if I pressed my leg quite hard into the top tube (and compensating by leaning the bike slightly into the leg) then the shimmy eased off and the bike felt much better at up to ~ 60-65km/h (about terminal velocity on those roads as they are only around 8%).
So, the "leg-being-pressed-into-the-frame" technique suggests it's dampening some imbalance (whether from lack of frame stiffness <unlikely>, aerodynamics and out-of-balance wheels)...
Anyway, I'll get the shop to check the bike out...
Hi, just wondering if the cause of the speed wobble was found? Are you enjoying the bike now? thanks
As the OP, the short answer is no, I still don't really know what the "problem" is. I suspect a steep head angle but I have no way of proving that and I don't have a second set of wheels I can swap out to do back-to-back comparisons against.
For sure, pressing my left leg into the top tube seems to damp down any vibration and the wobble eases...
I do enjoy riding the bike but have learnt to be cautious on descents or places where a cross-wind is likely
I’ve never ridden the Cannondale so can’t comment on that but find the TCR quite a smooth ride. Don’t get me wrong it’s responsive but not twitchy. I’ve ridden some road bikes that are too responsive for my liking that any input sends you off in a different direction but even then it’s not wobble
I would be check that
- Hub bearings are running freely but not loose
- Tyres are seated correctly on the rim ie you should be able to see the bead following an exact circle to the rim. That the tyres are are seated correct left to right ie spinning the wheel looking from above they look true
- Headset moves freely but not loose
- rims are not massively out of alignment in all axis
The fact is the TCR is a very competent well rested bike and doesn’t normally have these issues
If it’s new take it back to the shop and get them to ride it.
Finally when I moved from shallow rims to 50mm I really noticed it for about the first 3 rides, now I don’t at all
Cycling tips said the following in their review
Such flex between these two ends of the front triangle can go a long way to creating a bike that offers a nice ride quality, but it does detract from how the bike feels in an urgent surge of power. More importantly, both Andy and I each experienced a one-off bout of speed wobble in gusty conditions at over 75 km/h that we then couldn’t replicate (and I haven’t been able to get back to the same seated coasting speeds around my local roads in Sydney). James Huang experienced a similar thing on his stiffer TCR Advanced SL test sample and claims to have solved the issue by balancing the wheel.
That shouldn’t be a problem with a new carbon frame
It shouldn't, but I wouldn't have a huge amount of faith in that 😉
I wonder if you contacted the Peak Torque guy on YouTube if he'd be interested. This type of engineering/aerodynamic type query would be right up his street. Iirc he has a tcr too.
I had a TCR Advanced Pro and it was one of the most stable bikes I’ve had at speed . I decided to upgrade to the TCR Advanced SL as I thought it would be even better . I was wrong , it was too twitchy and although I didn’t experience speed wobbles on it I didn’t have as much confidence at speed on it. I think confidence is a big factor as I have had speed wobble problems a few years ago and it takes a long time to learn to flow with the bike again . Best bike for stability , feel etc I’ve ridden was a BMC SLR 01, absolutely rock solid at speed and could be thrown into any corners on any surface .
I have the same bike (or at least the 2021 version of it) - got it last summer.
A couple of weekends ago I went out on it and there was a foehn wind blowing (I live in the mountains). There were a couple of spots where it was blowing strongly across the road and it was really scary! Until then I had not been out in any strong winds. It has made me consider buying another set of wheels that are not deep-section for windy days.
Thanks for the responses. I'm basically on the market to replace my 2009 Cannondale CAAD9 Tiagra and have narrowed it down to a TCR Advanced pro 1 disc or a Specialized SL7 Expert. I love very fast descending and have never had an issue on my CAAD9. The Specialised would cost me £550 more with the main advantage of it having a threaded BB and integrated headset. Although from what I understand the headset spacers cannot be put about the stem so the steerer would have to be cut. I've ridden a friends SL7 briefly and got on well. No chance of riding a TCR as they sell out locally before the stock comes in. Has anybody ridden both?
I've just bought the latest TCR Advanced 0 and I have to say it's probably the best bike Ive ever ridden. I went through all the reviews before hand of which there are plenty & they are exactly right. In respect to descending I live in Bucks very close to Whiteleaf hill which is rapid very steep short descent - the bike is so fast going down it took me by surprise but I gradually got used to and it's no problem and handles the speed easily plus the disk brakes are amazing. The caveat to this though is that I would concur with those that have said confidence might be an issue as I was a very capable descender with top 10's on Strava leader boards but last year I had a couple of spills one in winter (hit some ice on a descent but pretty slow & one high speed on a corner hitting loose gravel) both really hurt me and I know that they took an impact on me psychologically. I've also experienced a speed wobble and on deep rims (pre sram Zipp 404s) but also had gusts catch deep rims wheels - in my experience they are two separate issues.
At 6'4" youre going to have a higher centre of gravity than many. Does this occur more on the hoods / less on drops? Perhaps try getting into a lower position on descents to drop your CoG a bit.
Or get a dropper post!