Folding Bikes - BF pulls/veers when riding
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01-05-08, 06:11 PM
I have a Bike Friday Family Tandem Traveler. I recently have done some short rides on it and notice that the steering seems to pull first to one side and then to the other. It's a handful to keep going straight. This is true even if both I and the stoker are sitting perfectly still and coasting. Any thoughts on what might cause this? Some more detail on the bike and what I've tried follow:
I bought it used several years ago, for my wife to ride with one of the kids, but that didn't happen very much because she never got comfortable on it. Maybe that's because the steering was a handful even when it was new -- I never rode it very much. But I think I'd have noticed it on the short test-rides.
The headset has a fair amount of friction when it is adjusted tight enough so that it doesn't "knock" when you hold the break and push the front end forward and back. This is after taking the whole headset apart, cleaning and regreasing and replacing the ball bearings at the top but not the needle bearings at the bottom. By "friction", I mean that it points where you pointed it, even if you tip the bike to the side. You wouldn't be able to ride it no-hands. I could buy a new headset but am reluctant to do that until I'm convinced that's the problem.
The front wheel was slightly off center (I checked in a truing stand), and putting it on center has improved the problem somewhat, but not completely.
The tire is a Conti Top Touring 2000 and it has diagonal, 1/8" deep grooves -- could these be causing it to veer?
Combined weight of me+child or wife is around 340 pounds. Could this be causing the veering even with us coasting, centered, and sitting still?
Thanks in advance.
01-05-08, 06:56 PM
I would contact Bike Friday direct with the model and serial number of the bike. They will have a record of when it was built and if there is anything special about it. They may even give you some advice on what to check that could be wrong. I suspect it was crashed and has a bent fork or worse. A photo of the bike from the side would help decide what might be wrong. I would first still get in contact with the builders at Bike Friday. I should have the 800 number here and when I find it I will post it if someone else doesn't beat me to it. Roger The number is 1-800-777-0258.
01-05-08, 09:33 PM
I second the recommendation to contact Bike Friday directly. I own both a Traveler XL tandem and an Air Friday. I've found the staff at BF very accommodating and helpful, even the sales reps. are not pushy but really try to understand what you want before making suggestions.
01-05-08, 09:51 PM
I wonder if a tandem was too flexible, if you could get into control issues where the rear rider is basically sagging one way due to frame flexibility, then the other way when it's corrected? Hard to explain. But does it do it without the stoker?
01-05-08, 10:22 PM
I have a Bike Friday Family Tandem Traveler. I recently have done some short rides on it and notice that the steering seems to pull first to one side and then to the other. It's a handful to keep going straight. This is true even if both I and the stoker are sitting perfectly still and coasting. Any thoughts on what might cause this?
This sounds like frame-flex, which is not normal on BF tandems. I have a couple of tandems, and have ridden a dozen or more. Check and make sure all of the frame connections are tight, your tires have enough air, and that no bearings are obviously loose. When I rode a couple of Bike Friday tandems they seemed rock solid. I do have a BikeE recumbent tandem that has some frame flex above 25 mph, not a difficult speed to reach on a tandem, but when we ride our KHS/ Nashbar tandem it is totally stable at any speed we have ridden it, max about 50 mph. By contrast, in the 70's I rode and sold some Gitane tandems that flexed back and forth as you rode them. Frame flex normally shows up as a wave-like motion which while scary, is predictable, going back and forth as you describe.
Some frame flex while both riders are standing and pedaling out of the saddle is normal. Frame flex while sitting and not pedaling shouldn't happen at normal speeds.
The headset has a fair amount of friction when it is adjusted tight enough so that it doesn't "knock" when you hold the break and push the front end forward and back. ...You wouldn't be able to ride it no-hands.
That does not sound right. I would replace the headset.
Overall team weight is less than my wife and I, should not be a problem. I can't see why tires should be any part of the problem as long as they have a decent amount of pressure. I used to ride at around 100 to 120 psi, but don't know what your Conti's a capable of. I would not recommend tires that can't handle 75 psi or more.
It is worth contacting Bike Friday since I do not believe this is a normal problem.
01-06-08, 12:05 AM
In regards to your headset, it seems as if you're tightening it too tight esp. if you can't spin the forks freely from side to side. I've noticed that because of the long handlebar stem, a little flex is normal when braking. I wouldn't tighten the headset to eliminate such flex.
Are you sure that knocking isn't due to an uneven rim or even low quality brake arms and pads? If so, then adjusting your headset to eliminate the knocking won't do anything. You might want to adjust the brake pads first. If that doesn't do it, then maybe higher quality brake pads are in order.
01-06-08, 08:31 AM
Thanks for the replies. I should have mentioned that I talked with Bike Friday a few days before the post. The person I talked with didn't really have any idea why it would be doing this.
In answer to other comments: The veering/pulling is not as bad without the stoker, but it's still there. The tires have a limit of 70 pounds. I think the headset needs to be replaced anyway, regardless of this problem, so I guess I'll just do it. Needle bearings are known to have more drag, but maybe the headset is just worn out. If the problem continues, then I'll take it to a bike store that's not too far away that carries Bike Friday.
01-06-08, 02:23 PM
Problem solved: Chris King to the rescue.
It occurred to me that while my main randonneuring bike is in pieces so that the frame can go back to the factory, I have a spare 1-1/8" threadless headset--my Chris King. So I put it in the Bike Friday, and lo and behold the veering/pulling problem is entirely gone. Woohoo!
I'm loath to pull it back off the BF, since it seems like the more times it gets put on and took off, the more chances to bend something and ruin it. So I guess I'll buy myself another one.
01-07-08, 11:40 AM
Glad you solved your problem. Tandems can be a lot of fun. Don't know where you are located, but try going to a tandem rally sometime. Lots of chances to try various bikes and learn tips and tricks!
I have been to the NW Tandem rally http://www.nwtr.org/ and it was really great. I hope to get to the one in Victoria, BC in 2009.
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