Modify cornering technique with high bottom-bracket?
 

I have a CX bike which I mostly ride on pavement. This has a 60mm BB drop, compared to 74mm on my other bike (a light tourer), and I've noticed it feels less confident (or at I least I do!) when cornering at speed. The whole bike just feels a lot higher, and less attached to the road on the curves. Tires are 35mm Schwalbe Marathon Supremes, which are semi-slick. I have noticed that these will skid fairly readily if I lock up the rear wheel with my (hydro disk) brakes at moderate speeds, but this could be perfectly normal with any tire.

Is the less secure sensation just a psychological reaction to the increased height above the road, or is it really going to be less stable?

Should I modify my cornering technique in any way to compensate for the higher BB, or just slow down until I feel comfortable?

I am trying to sit a little further back in the corner, ensure I am actually seated (to prevent the rear wheel losing traction), and try to put most of my weight on the outside pedal with the heel down.

Any other suggestions?

Thanks!

John

Yeah, you get to pedal around corners that other folks have to coast around. ;) I think if I ever ventured out on a "real road bike," I'd pedal strike in the first corner and end up on the pavement. I've honestly never noticed the high BB-- but my stork legs make for a 40.5" pedal-to-saddle measurement, so my CGH is crazy high anyway.

I think any uncertainty you're feeling in the corners comes from big, wide, heavy touring tires. Throw something thinner and lighter on there and I bet you'll rule out the high BB as well.

I have to force my weight back on a lot of bikes, but for me the issue is more my center of gravity being too far forward relative to the wheels. The solution for me is riding bikes with short chaintays and long front ends. I ride 175 cranks. If I have toe overlap (even if its just the fenders) that almost always means that bike is s so-so compromise for cornering and I have to remember to push my weight back.

The bike I raced was a '76 Fuji Pro. Very short chainstays. No overlap. BB was so high I rarely hit 175 cranks and i pedaled a lot of turns. That bike was scary early season but that was mostly a function of very quick steering. Once I was used to it, I trusted it completely on mountain descents. I never thought to push my weight back. That didn't start happening until I replaced it with a more conventional bike.

Funny this coming up. I see both of these issues now that I am running my Peter Mooney fix gear. I decided to have the bike built with a highish BB. Good move! I love it now after second guessing myself for 35 years. The bike was designed to be able to do everything but race. It has long chainstays for touring loads and big tires. Front end was kept in a bit to keep the wheelbase reasonable. Too short. I have to push back a bunch to corner. Big soft tires, esp in back help a lot. I'm planning to get the 28c Vittoria Graphene tires, hoping they will help.

Interesting! I had thought that wider tires at lower pressures would add traction and make the corners feel more planted, but maybe not! My Trek Crossrip (74mm BB drop) has 32mm tires and feels under better control on the same corner, but the geometry is different - 25mm longer wheelbase, lower CoG, slower steering...

I also feel as though I'm further forward on the CX bike and have some toe overlap (not too much, but some). I do feel more secure when I'm further back on the bike, like you. I think I can get used to the CX bike, but it's interesting to note how different bikes can feel with small changes in the measurements (10-20mm)

it's real, the lower BB puts your whole center of gravity closer to the floor
I felt a difference (improvement) going from a 70 to 72.5 drop, with same crank length

The higher COG is real, but also in perspective it's a relatively small change. Depending on the pedals you're using, you could get close to half that back by going to shoes/pedals with a lower stack height.

Also the difference between a 23mm tire and 35mm tire has close to as much difference on your ride height, and therefore COG.

And the difference between cornering in the drops and cornering on the hoods is going to be at least as big effect on your COG.

So if you're not cornering in the drops now, doing so will increase your stability, and if you already corner in the drops, a deeper elbow bend will lower your COG.

Good point about the tire height - I'm pretty sure the 35mm Schwalbes are significantly higher than the 32mm Vittoria's on my other bike.

Nice suggestion to bend my elbows more to get my body lower on the corner. I'll try this out!

Thanks,

John

you havent mentioned how much you weigh and what pressures you are running. In my experience this makes a big diff in handling feeling, so put out the numbers and I can relate to cornering with 28 gatorskins on my cx type bike, and on my touring bike that I have supremes, but 26x2, 50mm which actually measure out to 45 on my rims.

I feel a very noticeable diff on any bike with appropriate, ie lower, pressures for better handling (loaded or unloaded)

Good point. I weigh 70kg (156lb) and have the 35mm Schwalbes at 65-70psi front, 70-75psi rear.

others may have a better take on this, I'm a real lightweight, only about 135 and on my 28s I noticed a real difference from being at 100psi at both ends, to maybe 80front, 85rear in cornering being more secure.
I ride some 37/38mm regular marathons on my old mtn bike and can use 45f 50r easily, so I guess the only thing I could suggest is to try some lower pressures and see if it feels better. In general, lowering pressures will give you more "suspension" effect from the tire in a corner, which is more confidence giving, and also will give a certain amount more traction than higher pressures, although I certainly can't give an answer to how much, I just know I feel more secure cornering at lower pressures (but of course, too low and you get tire movement which isnt good either, sort of feels "wallowy", which I dont like to feel in a corner)

all this blah blah is of course just blah blah, and lets face it, cornering and how someone "feels" cornering depends on so many factors-riding skill, body position weight etc, how you go into a corner, taking the apex at a right speed for that corner, that surface, those tires.....to me there are too many factors that come into play, and while I freely admit not to really knowing how bb height plays a part, I can't imagine its much of a factor, lots of others things are going to be more important.

but who knows.
have fun experimenting with tire pressures anyway, at least that is something that you can compare feelings with the same corner or corners at diff pressures.
cornering technique, well, thats a whole other kettle of fish, and certainly not something you can learn on the interwebs.

Moving the seat back, or using a longer crankset will also lower your seat, and lower the center of gravity.

However, how many miles have you put on the bike? Go out and ride a couple of century rides (100+ miles), and you'll quickly habituate to the feel of the bike.

I had a couple of longer rides on routes with a lot of corners over the weekend, and tried a few of the suggestions.

I found that deliberately dropping my inside shoulder, and using this as a reminder to push my weight through my outside heel, really made a difference to my confidence. Just getting lower over the bike in the corner and getting a bit more weight over the from wheel made me feel much more in control.

Thanks!

John.