Bike skipping

Rhod81

Hi everyone,

Thought i'd post here, as the only "racing" i do really is some Strava-bashing, but thought you guys might have a bit of insight.

I have noticed that when really pushing it on the flat (29-30mph-ish), i can feel my back wheel getting all "twitchy". Frequently get the feeling of losing contact, squirming about, even skipping along a bit!

I've previously put this down to poorly surfaced roads, but i have noticed it occurs quite often when hitting those speeds on the flats. Consequently, i'm guessing it may be a technique-thing as it doesn't happen when doing 30 down hills. Any ideas!?!?

Bike is an Allez elite, Fulcrum racing 7's, conti gatorskins...

Ta.

markynulty

You could be running too high a tyre psi for the conditions.

ellj22

When seated or standing? Are you pushing a higher cadence than normal?

Possibly you are pushing a higher cadence to achieve these speeds than usual and it is causing you to 'bounce' slightly, nothing a bit of leg speed work and core strength won't fix (check saddle not to high). Another thing to look at is pedalling technique, a bit of mountain biking on muddy ground should help fix this. You need to keep the power delivery smooth, aim to apply a more even power throughout your pedal stroke. You could also try shifting your weight slightly rearward to keep the back end more planted.

It doesn't help that gatorskins aren't very supple, commonly referred to as hose pipe due to their hard, unforgiving carcass.

Tom Dean

I used to get this on one of my bikes when pushing very hard in the saddle. Probably a combination of position and getting a bit ragged when on the limit.

Rhod81

Thanks both,

Markynulty, i tend to run about 100psi, but at about 90kgs i feel its a good compromise between fast rolling and grip. Any less and it kind of feels like im running on a flat almost!

Ellj22; its seated. i tend to average a cadence of 95, maxing out at about 180. Saddle im pretty sure is ok. But thanks for the other bits. I guess i kind of neglect core strength. Also, leg speed... How??? Lol. As for the mountain biking, i used to do quite a lot but haven't so much as been off-road now for 18 months.

As for gatorskins, any recommendations? I wore out the originals, and then went for a few pairs of cheap shwalbe Luganos before getting fed up of regular punctures and investing in the gatorskins. I must say, i love 'em! In 4000 miles ive had three punctures (all of which snakebites).

Thanks again.

Rhod81

Tom Dean, did you manage to overcome it?

DeVlaeminck

This is a strange one as at a constant tempo seated I can't see how a bike would skip as most of the weight is on the back wheel.

180 on the road is a decent max cadence, 100 psi at that weight low side of normal for 23 mm tyre so no clues there. 3 snakebite punctures in 4k miles - I've had one in maybe 60,000 - is it possible your tyres are too low and the skipping is actually squirming? Maybe a faulty gauge?

Bottom line is either the wheel is being pushed up from below - probably hitting bumpy road surface at speed which you don't notice on descents because you unweight the saddle or else you are pulling up so hard or moving the body so much it takes the weight off thewheel - seated I'd guess the former.

Tom Dean

Rhod81 wrote:

Tom Dean, did you manage to overcome it?

The frame broke. That frame was on the small side for me (I used 140mm stem) and was tight in the rear with short chainstays. Great on smooth crit circuits but not so nice on bumpy roads.

tetm

Have you checked there's no play in the back wheel and that the hub cones are tight enough? A bit of hub movement at those speeds will cause squirming.