So my wife has just upgraded her bike from…

Spec Epic – 100mm forks; 71HA; 90mm stem ; 23″ wide bars

To a

Blur LT – 150mm forks; 68.5HA; 80mm stem; 26″ wide bars

And is complaining that the bike feels “twitchy”; this has surprised me as you’d think going from basically an XC race bike to an AM bike would be the opposite.. Am wondering what could easily be done as a test to slow the handling down.

Put narrower bars on it,or a longer stem.

Tyres different? Tyre pressure and sag set up will need to be right for her. I couldn’t get on with the Continentals fitted to my bike so swapped them for Kendas I’d had on my old bike and instant happiness

Does she mean twitchy or vague? You could certainly see it being more vague

I suspect it’s not twitchy as such, just that she is sitting in a position where less weight is on the front, so it wanders a bit.

Is the stem as low as it can be? Can you turn it over?

Get her to ride it for longer and/or fiddle with the suspension? The cockpit is abstractly more relaxed.

Same tires (well Nobby Nic 2.25’s instead of 2.1’s). The word used was twitchy.. so that’s what I’m going on. Will consider narrowing the bars; stem is about the right height and 10 deg rise but could flip it as a test.

Check the fork setup http://locotuning.co.uk/tech-info.html the longer travel forks may be a bit more ‘divey’ so feels odd to her.
Maybe no enough low speed compression so dives on the brakes and into corners, steepening the headangle and causing the ‘twitchy’ feeling

A mate compared my 28″ bar, 68.5HA, 50mm stem bike to his ~24″ bar, 100mm stem, 71HA bike yesterday, at low speed and said much the same. I’m sure it’s because at low speed the long stem and narrow bar makes the response more stable whilst once the bike gets moving the trail and ‘flip flop’ from the slacker head angle dominates the stability slowing down the sharper short stem. Also at low speed slacker angles make a bike feel more wobbly.

As the cheif says, the slacker the bike is the more ‘sloppy/wandery/prone to ‘fall’ into corners at low speed it will be, the trade off being greater stabilty at speed and when lent over in the corner.

Narrow bars will make it more twitchy. Have you given it a ride to see how you think it feels?

How does the saddle to bars measurement compare between the two bikes? Maybe its the riding position that just feels odd?

Fork dive? Shorter wheelbase? Rounder profile tyres?

The higher BB will also make it feel less stable/more twitchy. Just something to get used to, me-thinks.

Thanks for all the thoughts – Interesting comments about the speed aspect; that’ll be an interesting one to sell.. “I know it feels unstable but if you just hit this technical section at speed it’ll all be okay.. trust me….”

The old bike is no more and to me the new bike feels fine in a car park.. but I’m comparing it to my Mojo SL which has very simmilar geometry to the Blur LT.

The bike is much shorter (by about 1/2 an inch on a medium) so changes in the riding position probably also a factor.

As the new bike is shorter her weight will probably be a bit further back than she is used to try lowering the stem or flipping it if you have no spacers under it. This will bring her weight further forward like she is used to.

The change in the centre of gravity is key here, I swapped from a 69.5 degree 130mm bike to a 67 degree 150mm bike with supposedly a low BB and found it a little vague and nervous too. A steeper HA bike is generally longer in the top tube and thus you straddle the bike and keep your weight at a constant point. A shorter top tube on a slacker bike will mean that you have to move your weight around a little more. That was my experience at any rate.

A lot of this is down to simple set up, if you’ve spacers to lose underneath the stem then do so, as lowering the bars will move weight forward and down. Likewise, pay careful attention to the sag settings, too much rear sag will shift weight back and will make the front end feel wallowy, especially if there’s too little sag up front.

I really wouldn’t opt for narrower bars though. By all means play with the stem length, but I think the key here is stack height.

Also, fitting a soft compound front tyre may help with the front end vagueness.

just ride way ahead so you don’t have to listen to her like so many married men seem to when they go biking with their missus.

No no no, ride behind shouting at her to go faster.

Thanks all (except may be the last two.. 😀 )

interesting. i’d start by maybe putting the old bars and stem on new bike.. reduce them variables 🙂

i think maybe being “too slack” can appear twitchy as the tiny movements you’re used to making to keep balance become bigger movements and it takes time to adjust.

Why is she on the bike anyway when she should be preparing your post ride dinner.