[Closed] Rear wheel flex. .. How to stop ?

Think this one has come up before and this link got shared by someone...

http://www.slowtwitch.com/Tech/Debunking_Wheel_Stiffness_3449.html

Not a quick answer and it's pretty road focussed, but nice and geeky... 🙂

is it built differently to the way it was before, or same rim, spoke setup ?

Take it back to the builder.

I agree with fasthaggis. If everything else is the same, the build is the problem.

Do you have much tyre clearance? Is it genuinely wheel movement or could the tyre be rolling on the rim? How big are the tyres you’re running? Any movement in the dropouts or the hub bearings? Can you flex the wheel by hand?

Would a change to straight spokes help

Well you'd need a new hub to do that so a bit drastic

or a stronger rim ?

If built correctly

Almost like the tyre pressure is low.

Is it?

Was it flexy before the rebuild?

What do you weigh? HT or FS?

get a pair of wheels built to suit your size, and type of riding you do.

I don't know how flexy it was before as I bought the wheels secondhand from here and found the hub cracked straight away.

I meant would plain guage spokes be stronger than double butted.

Wheel is built fine. The builder is quite well known in the area for his wheel builds. All spokes are correct tension etc.

I can flex the wheel a bit by hand. The tyre is a 2.3 with plenty of clearance.

Sorry forgot to add....

Full suss Codeine with maxle rear end.

I am 110kg

Is it definitely the wheel flexing? Not the frame, or the hub is not right?

Also is the tyre on straight? Had tyre rub the frame before because they just weren't seated right and had excess wobble. The wheel was perfectly true though. Though if it feels flexy I guess it's less likely, unless it's not seated right at all and thus squirming a lot.

What was the builders opinion,did they suggest anything?

Edited: because I'm an idiot.

You say the spokes are the correct tension, how do you *know*...?

Which wtb rim? ST? Frequency? Kom?

I23 rim.

Wheel builder suggested plain guage spokes.

Wheel built and tested with a spoke tension meter.

Try another wheel in there, I reckon there is more chance of an on one flexing than that wheel, and tyre deformation is a good shout too.

Sorry,I should have added.

Have you spoken to the builder about the problem since the initial build?
They would be my first contact if it's not right,or rubbing the frame due to flex.

i23 is the width, wtb make a few different rims with that width / suffix.

(For example, the Kom rims seem very light for an aluminium 29er rim. Light, stiff, aluminium, pick 2)

Which spokes? Dt comp have a 1.8mm diameter, dt race (?) are 1.5...

I think the spokes are 1.8 - 1.5 - 1.8.

I reused the original spokes.

Maybe some plain guage spokes would help.

The wheel builder did say they were more of an xc build spoke and that I may get some flex too.

Edit : rim is wtb st i23.

I'm not convinced the frame is flexing either as it's built like a tank.

1.8 - 1.5 - 1.8 and 110kg will make the wheel flex under hard load so I'd suggest a heavier guage spoke, like a Sapim race, or perhaps a diet.

17+ stone? I think there lies your problem.

Plenty of heavier riders on here than me mate.

Yes, but you're on a relatively narrow rim with quite thin spokes.
I only meant that your weight's only an issue in respect to that 😉

So should I try a spoke change or would a rim and spoke change be better ?

If so what rims and spokes ??

I think you should speak to the builder and get some advice from them.

Wheel built and tested with a spoke tension meter.

But do they *feel* tight now? (Squeeze test)

I'll bet that they've gone a bit slack after riding the wheel.

I'm not convinced the frame is flexing either as it's built like a tank.

Just because something looks 'clydebuilt' does not mean it is stiff.

Try a different wheel in there, either that, or just do as you usually do - come on here, ask a question, get lots of helpful advice and ignore it, as it's not what you want to hear.

1.8 1.5 1.8, what spoke is this, revolutions? That guage would be a race day weight weeinie spoke surely.
2.0/1.8/2.0 competitions would be good and DT rate a 28hole xm spline wheelset to 120kg. 32h sees you plenty strong for 110kg. I have a similar weight pal rinding my old 32h xm471/204/competition build and its the first set of wheels that he's ever found to be stiff.

I weigh 35kg less than you and I only use 1.8/1.5 spokes on my lightweight race wheels.

Wouldn't dream of anything that light on a general trail bike even for me. I hope it's not a low spoke count wheel too...

Go back to the builder and ask for advice on a build for your weight and riding. There's nothing wrong with being heavy, but there is something wrong with using inappropriate components for your weight.

Thanks all.

Would the rim be strong enough then do you think ?

I'm sure it's a 32 hole rim and hub.

The wheel builder did comment on the spokes when he was building it as they were the spokes from the previous build.

I will go and ask his advice and see what he says.

Cheers.

So should I try a spoke change or would a rim and spoke change be better ?

If so what rims and spokes ??

For a nice solid build something like a Stans Flow or DT Swiss EX511 with 2/1.8/2 DB spokes.

I had similar problems with my first 29er (a hardtail). I'm about 86kg with full winter kit on, and tried some Pro2 + Crest wheels on there. Trail centre reds were mostly OK, but on rougher natural rides it felt like the rear axle was loose - it wasn't, it was the rim flexing. Swapped to Arch EX's with same hubs and spoke type, and that solved the problem.

If you want a decent quality stiff rim, I can recommend the latest 25 & 30mm internal width DT stuff - have some of the 30's on my long travel 29 and they are brilliant. No flex, but not harsh with it either.

Cheers.

What models are the decent dt rims I need to look at then.

To my the flex felt like the tyre was rolling on the rim. I kept checking as I thought it was going down but it wasn't.

Tyre is a 2.3 ground control set up tubeless.

I had this and had the wheel rebuilt twice.

It turned out to be the one of the pivots on the rear Tri.

Whoops.

ex471 25mm 530g
xm481 30mm 525g
xm421 25mm 465g

I'd probably go the 481.

Ooof they aren't cheap are they.

How would an st i29 compare to the i23 that I have ?

CRC have them on offer ?

is it a pro/shop who are doing build ? will they be happy building bits you buy online ?

I have i29 Asyms on the Bronson, Don't think I'd buy them again, they are nowhere near as robust as my previous DT swiss were, XM1501's.

They ding very easily.

Wheel builder sounds a bit daft TBH. He/she shouldn't have built the wheel up for you with those spokes in the first place.

Nah I can't blame the builder as I said use the original spokes to keep the cost down.

Hindsight and all that .....

I can't afford to spend £70 odd quid per rim to be honest. So what's my options.

I build all my wheels with plain guage 2.0 spokes and have no issues with wheels flex

So what's my options.

A new hobby, I'd suggest. I can't recall a bike you've ever been happy with.

Nope mate I'm quite happy with this as it stands.

Apart from the wheel obvs.

what's my options.

Buy a wheelset from Merlin that meets your weight and riding requirements, sell the ones you have

why not just buy stuff suitable for your weight?

good wheels are THE most important things on a bike, for a heavy rider.

why not just buy stuff suitable for your weight?

good wheels are THE most important things on a bike, for a heavy rider.

That's what I'm trying to do ton.

I didn't realise at the time I bought the wheels that they had the thinner spokes on.

I thought the wheel would be ok to be honest but as I've got more used to the bike it's starting to highlight that it's not.

I've been out and checked the frame and it's solid. No play in the bearings etc.

Hi Renton, it's not just you and your bike parts. The Horsethief frame I bought from you bucked me off and now I have a broken leg.

Flex does not come from play in bearings.

True but it can be a cause of wheel rubbing the stays which is the problem .

Healing vibes Wally.

Just get it rebuilt with thicker spokes.

Thanks, it was 100% pilot error and bad luck. Frame is a peach.

Just noticed your tyre choice - is it the control or grid version of the Ground Control? If it's the control version, I'd say this wouldn't be helping the situation. IME, the sidewalls are really lacking in support and feel a bit wibbly with a bit of aggressive riding, and this is made worse when they're on a narrower rim (I've tried 2.3 GC's on rims with internal widths of 21, 23 and 29mm).

A cheap option for you might be to try a tyre with a stronger sidewall. Something like a Mavic Quest - they're designed for rims with 23mm internal, and have reinforced sidewalls. Grip is about the same as a GC, but they're a bit heavier and the tread can wear out pretty quick - nice and stable though. (Blatant plug - I could sell you an unused one from my tyre cache for £15 posted;))

Sounds like a good opportunity to learn how to build a wheel. It's really not that hard, it's even good fun.

Your first wheel shouldn't take more than a couple of hours, and 32 sapim spokes will cost about £20.

(The rim you have should be stiff enough)

This is why I love the custom wheel build option on Superstars website.
You can choose their own hubs, rims etc or branded stuff from DT-Swiss, Stans, Mavic etc...then choose the type of spoke you want from bladed, to plain gauge to butted etc...you'll basically end up with a suitable wheel for the type of bike you own, the riding you do and your weight instead of the usual shite specced on most complete builds.

Can I just ask something .....

These st i25 rims on offer at on one for £9.99 ......

Would they be ok with a decent plain guage spoke.

Cheers.

Steve.

Is the bike a 29er?....isn't boost spacing supposedly a solution to the inherent flex of bigger wheels and a big chap riding one?

The i25 rim is decent, I don't know enough about spokes I'm afraid.

renton - Member

These st i25 rims on offer at on one for £9.99 ......

Would they be ok with a decent plain guage spoke.

Cheers.

Steve.

they're a hefty rim, at something around 600grams. While there's more to stiffness than simply using more metal, it's good start.

1) use plain gauge spokes and you should notice a significant difference.

2) the wider rim would help a bit too.

(i suspect most of the improvement will come from the spokes, which is where most of the strength/stiffness of a wheel comes from. But still, a slightly wider rim should be stiffer, and as it's only a tenner, it's probably worth it)

deviant - Member

Is the bike a 29er?....isn't boost spacing supposedly a solution to the inherent flex of bigger wheels and a big chap riding one?

yes, but that would need a new frame, and hub. All for more or less the same increase in stiffness you'd get from an offset rim, or even just a well built wheel... i'm happy to see incremental improvements, but if you've got a not-boost frame, and you're worried about lateral wheel stiffness, there's all sorts of things you can try before dumping your old frame in a canal.

Thanks for the reply

they're a hefty rim, at something around 600grams. While there's more to stiffness than simply using more metal, it's good start.

They are 14 grams heavier than the i23 which I can live with.

I guess changing from the spokes I have to plain guage will add quite a bit of weight.

Any recommendations on make of spoke ?

Also if you buy new rims how do you find what spoke lengths you need etc.

[url= http://www.wheelpro.co.uk/wheelbuilding/book.php ]buy this and read it[/url]

dt swiss spokes are really good.

as far as i can tell, sapim spokes are just as good, and about 2-thirds the price.

there are online calculators to tell you what length spokes to use, you just type in some easily measured details about your hub and rim.

but, i'd be surprised if there was much/any difference between the effective diameter of a wtb st i23, and a wtb st i25. so you could just measure the current spokes, but you'd need to take them out to measure them (1 each side, they'll probably be different lengths)

i bought the roger musson book, it's great. don't be put off by the size of the book, the bit where you actually get stuck in and build a wheel is covered in about 4 pages, with lots of big diagrams.

(my favourite tip: cut the end off a cotton bud, flatten the plastic tube, hey presto! nipple driver)

renton - Member
These st i25 rims on offer at on one for £9.99 ......

Would they be ok with a decent plain guage spoke.

renton - Member
I23 rim.

Wheel builder suggested plain guage spokes.

renton - Member
Thanks for the reply

They are 14 grams heavier than the i23 which I can live with.

I guess changing from the spokes I have to plain guage will add quite a bit of weight.

Any recommendations on make of spoke ?

Also if you buy new rims how do you find what spoke lengths you need etc.

I think you need to ask the wheelbuilder what he advises, seeing as he is building it....

Decent wheels make or break a 29er in my opinion, way more so than on 650b or 26. You're a big lad Renton, you need a stiff back wheel. I had a similar issue on my Spearfish, felt like something was loose or that I was rolling a tyre when in fact it was just a cheap rubbish wheel from superstar flexing a lot.

My suggestion would be sell the wheel and buy something like a Flow. I personally wouldn't reuse spokes (I've built a few wheels myself) and I certainly wouldn't go for some as thin as the ones you've got. And I'm not 110kg either so the extra weight is only going to make a bad situation worse.

As said above, I'm not digging at your weight.

At one point I was 100kg and found riding any kind of FS a weird sensation, I'm sure they're engineered to take the weight but I doubt many test riders are that heavy...most pro riders, factory employed development riders or even just bike journos reviewing prototypes appear to be racing snakes...it's often the same with Japanese motorbikes, they are usually designed and set up for the typical Japanese male who is (massive stereotype coming) shorter and lighter than European and American men...when I was 100kg I found riding my steel HT far more satisfying.

I'm now 83kg and my FS feels fine, I'm still probably heavier than the mass market air suspension products are designed for as fitting coil forks and a coil shock has the bike riding far better but with an obvious weight penalty.

Everything is a compromise....with your bike I'd love to stick a 650b wheel in the back while keeping the 29er up front, you'd still get the roll over ability of a 29er as the rear wheel just follows the front but it'd slacken out the HA some more, you'd probably get a stronger rear wheel out of it and it'd get marginally lower in the BB...i reckon that'd be a beast!

Have just rebuilt my rear wheel (KOM i23 29er) on my SC Tallboy after the old rim split. Used the original spokes (DT Competition 2.0/1.8) and moved to an i25 rim but have put a little more tension on them than the old build. I can't feel any flex through the wheel and I certainly can't move it by hand in the frame. I'm pretty lardy too (90kg).

I'd be checking wheel bearings too. Recently had an Intense pass through the garage which had a little bit of wheel rub - wheel bearings were gone although it was impossible to tell out of the bike and you could only just tell even when fitted, but the impact to the ride was huge. Same goes for linkage bearings...

So just to update I've been offered touch with my wheel builder and this is his reply....

Hi Steve, re re-building your wheel with stronger, larger diameter spokes to make it a more rigid and stronger wheel:

Plain gauge 2mm (14 gauge) spokes would be my recommendation. Plain gauge spokes are the same diameter for the whole length of the spoke; it’s a stronger, more economic choice. Double butted spokes are a smaller diameter in the middle section, it saves weight but they retain comparable strength in terms of a completed wheel, they are more expensive though.

36 plain gauge spokes would cost £28, 36 butted spokes would cost £45. Prices include nipples, both are stainless steel, black spokes. Building cost: I haven’t increased my cost for building wheels, it’d usually be the same as last time, £45, I’ll reduce that by £10 for you.

That sounds fair enough I think.

I'm still considering upgrading the rim from an st i23 to the i25.

Will I notice the difference?

What are you going to do with the 4 extra spokes...?

I stand by my previous statement - 29ers need decent wheels, stiff and light being top of the priority list. I personally wouldn't go for an i23/25 at your weight, I'd be more inclined to go for something like a Stans Flow.

For the sake of £17 I'd get the double butted spokes, remove as much weight as you can out of it with compromising strength.

I weigh 110kg clothed and didn't fanny about with the wheels on my 456. Straight spoked Mavic D521s, a Hope Big 'un front and Sport rear. I'd much rather lug the extra pound or so around with me than have flimsier wheels to worry about.

Yeah ok, the Big 'un is OTT and could be replaced by something just as strong and much lighter but I love that hub.

Just to throw a spanner in the works, is the tyre rubbing on both sides or just one? If just one, it could just be that the dish isn't quite right.

1.8/1.5mm spokes are pretty thin, whilst I'm not convinced they'd really allow that much extra flex, 2.0 or even 2.0/1.8mm spokes will help a bit.

I'd suggest a smaller tyre if the tyre's touching the frame though.

Both sides mate.

Fair enough, not dish then!

IIRC DB spokes are stronger than PG spokes, or at least they should last longer. Whether they're stiffer though.

I'd just sell the whole wheel/wheels and buy a different set. Saves fannying about and will probs work out the same.