Tall Wheel Speed Fallacy: An interview with Tim Brummer

This is a Podcast where Tim Brummer, a much accomplished engineer and owner of Lightning Cycle Dynamics, the fasted production bikes on the planet, discusses the misperception that taller wheeled recumbent bicycles make a for a faster machine. He even shows that smaller sized wheels can make for an increase in speed …


Martin Krieg: Welcome to the National Bicycle Greenway’s Mountain Mover podcast series. Here you will get up close and personal with people who are taking giant steps for the betterment of cyclists and for the planet itself. Tim Brummer, highly respected engineer and maker of the record-setting Lightning Cycles Dynamics is gonna talk to us about the misperception that recumbents with two tall wheels are faster than those with shorter smaller wheels. How are you doing today, Tim?

Tim Brummer: Just fine, thank you.

Martin Krieg: All right. Well, uh, explain — as I return to the recumbent industry, after five years using the 1891 Eagle High Wheel instead of recumbents to advance the National Bicycle Greenway you’ve long supported, I’ve noticed that big wheels, the big wheel recumbents, the 700c wheels, seem to — uh, seem to be seen as the price you have to pay to go faster on a bent, That what you give up on the way of handling, you make up in the way of speed. Can you speak to this?

Tim Brummer: I could say that actually, larger wheels are slower. There’s been a lot of research on that. A lot of it has been done by Chet Kyle, who started the IHPVA. And back in the 80s and 90s, he did a lot of research for the U.S. Olympic team, mainly for their time trial bikes or team pursuit bikes. And he did a lot of research on rolling resistance for different sized wheels and tires. Basically the bottom line was that if everything else is the same, the tire diameter didn’t make much difference; a small wheel can have a low rolling resistance — the same as a larger wheel and tire.

It’s more a matter of the tire casing designs, whether it’s supple, has a high tread count, and of course the PSI and the rubber and the tread pattern. As far as rolling resistance, the diameter has little effect. It’s all those other factors that make a tire fast or slow. And we’ve done some of our own tests too here at Lightning Cycles, and the one thing that we noticed was with a small-diameter wheel, it’s better to have a a slightly wider tire, like a 25C on a small diameter wheel versus a 23C on a bigger wheel. What that does is, the wider the tire, then the less flex on the contact patch. So, that will make the rolling resistance a little bit lower, also.

Back to what Chet Kyle was doing, what they came up with was that the smaller wheels are faster not because of the rolling resistance but because just by being smaller they’re gonna have a lot less wind resistance, and also less weight, so you can accelerate faster. During the 90s, our Olympic team bikes and a lot of the Tour de France time trial bikes were going with smaller wheels. On the Iron Man especially, the Iron Man bikes were all going with smaller wheels and they were winning.

So, the UCI comes along and of course, they banned the smaller wheel ’cause it’s faster.

It’s just like when they banned recumbents back in the 1930s, I guess.

Martin Krieg: Uh-hmm.

Tim Brummer: So that’s why today now you’ve seen all the Tour de France bikes, they all get 700C wheels because that’s what’s regulated, not because it’s better but because that’s what the UCI regulates. So the fact is that smaller wheels are faster. I mean you see people on bike Fridays and Moultons, those have small 20-inch wheels front and back.

Martin Krieg: Uh-hmm.

Tim Brummer: And they’re just as fast as a bike with 700C wheels. You know, it’s all of the other factors, mostly the rider, of course. Now, on our bikes we use a smaller wheel in the front because that’s where it makes the biggest difference. That’s out there in front in the wind stream. The biggest advantage actually the small wheel gives us is not so much just a lower wind resistance of the wheel itself, but we can make the rider a lot lower, you know, one foot lower — and that decreases the wind resistance of the frame because now you’ve got most of the frame drafting in the slipstream with the rider. And also half of the back wheel, if you go with full-size back wheel which sometimes we do. Sometimes we go with a 26-inch or a 650 in the back. That’s why we’re using a small wheel in the front … it’s faster. It gives you a lot less wind resistance, not just the wheel but also you get the rider lower; you can streamline the frame a lot more. It’s big advantage having small wheels especially in the front. On the back, because it’s behind the rider so wind resistance-wise it doesn’t make a big difference, the big advantage of a small wheel lets you lean back more, so that is a big ergonomic advantage. That’s why on our own mid-racer bikes we use a 26-inch wheel in the back so you can lean the rider back more and that’s the biggest advantage that the Bacchettas have. It’s not the wheels but the they just have the rider leaned back. That’s what makes them faster than upright bikes.

But by the same token, our mid racer bikes also lean the rider back. Plus, we have an additional advantage of lower wind resistance from the front wheel, less resistance from the frame, and less wind resistance from the back wheel because it’s drafting behind the rider.

Did you understand all that or did you —

Martin Krieg: I did, it’s fascinating. Thank you, Tim.

Tim Brummer: Okay, yeah.

Martin Krieg: Let me ask you a question, um, obviously …

Tim Brummer: Yeah.

Martin Krieg: That’s the reason we’re doing this. Um, I’ve long known you’re an engineer. Where did you study at?

Tim Brummer: Northrop University down in Los Angeles.

Martin Krieg: Northrop, okay.

Tim Brummer: Yeah, it was started in World War II by Jack Northrop, the guy who started Northrop Aircraft Corporation.

Martin Krieg: Huh, okay.

Tim Brummer: The company that makes the Stealth bombers.

Martin Krieg: Uh-huh. So, did you actually ever do any engineering besides bicycles?

Tim Brummer: Oh, yeah, absolutely. Before I started the company, I worked for Rockwell International and they got bought out by Boeing.

Martin Krieg: Uh-hmm.

Tim Brummer: Back then, I worked on the B-1 bomber; I worked the space shuttle …

Martin Krieg: Really?

Tim Brummer: I worked at Hughes Aircraft on some of their projects. I worked for Lockheed Martin on missiles and rockets and — and spacecraft.

Martin Krieg: So, you’re working on — on classified stuff then?

Tim Brummer: Oh, yeah. I had top secret clearance.

Martin Krieg: Hmm.

Tim Brummer: That’s when I was working on the the secret spy satellites.

Martin Krieg: Hmm.

Tim Brummer: We were launching those into orbit from Vandenberg.

Martin Krieg: I — I know you wouldn’t allow yourself to brag about this, Tim, knowing you, but uh, were you a top engineer back then?

Tim Brummer: Yeah, I was. I was a group engineer, I had 20-30 people working for me.

Martin Krieg: Oh, really? Wow. Even back then —

Tim Brummer: At the end of Cold War, the Soviet Union collapsed and a lot of those jobs and programs went away, so that’s when I decided I wanted to just do something to give me a little more freedom to express myself, you know.

Martin Krieg: Uh-hmm.

Tim Brummer: When you’re working for the government, you’ve got to do what they tell you; you don’t have much latitude. In any big organization, you’re kind of stuck. You’re limited to what you can do.

Martin Krieg: Wow. Uh, on the Olympic funny bike that you were talking about that smaller front wheel — they were 24-inch, is that what it was?

Tim Brummer: As I recall, yeah. What they did, they actually had a couple different ones. The one for just a single rider, like in an individual time trial. They would have a 24-inch in the front and a 700C in the rear. But then they have another event called the team pursuit where it’s four guys riding together, or the team time trial. The whole team will go faster if you can get the riders closer together. They can draft closer pulling one behind the other.

So in that case, they have 24-inch wheels front and back because that lets the riders ride closer together and the whole team is faster that way. So, that’s what I’m saying, smaller wheels are gonna make you faster.

So on the back wheel, it’s more complicated, you know, there’s a trade-off because you’ve got gearing. And then you’ve got to take into consideration the comfort factor, because if you hit a bump on the front, you don’t really feel it maybe in your hands, right? But when you hit a bump on the back wheel, it goes straight up your back and your spine, so that’s the one advantage of a larger wheel on the back, is it’s more comfortable going over a bump.

So that — plus you can get a bigger gear. That’s why we’re using like the 700C on our P-38 and R-84 models, because we put the full fairing on there and those things go really fast, you know, 40-50 miles an hour. With a bigger wheel you can have a big enough gear — like 150 inch gear — to take advantage of the speed the fairing gets you.

Otherwise, you’d be spinning out the pedals at 30 miles an hour if you had a smaller [wheel] in the back. So for those two reasons, we’re going with the 700C in the back: Better comfort, and you can get much higher gearing especially if you put a fairing on it.

Martin Krieg: Well, Tim, coming back to the comfort factor of bouncing over, I know we’ve talked about this before, um, bumps on a, higher — higher diameter wheel. On a long race such as RAAM, uh — well I’ve never asked this question before: will the bigger wheel rider be faster because he or she will be more rested from not having to absorb as much road shock?

Tim Brummer: No, I mean it does make almost no difference. We did RAAM, we had a 17-inch wheel in the front, no suspension, and it doesn’t make any difference, really. When we’re doing RAAM, there’s a lot of just pedaling day after day. That’s what wears you out.

Martin Krieg: Right, right.

Tim Brummer: That’s the thing. The roads on RAAM are not that bad, though.

Martin Krieg: Are you still the world record holder for RAAM.

Tim Brummer: Yes. We still have the cross-country record set 25 years ago: Five days one hour. And nobody’s been able to break that.

Martin Krieg: Uh-huh. And what’s the closest time next to that?

Tim Brummer: Well, we did it again. The second time about two years later and we got the second fastest also. Five days five hours, I think it was. We were trying to break our own record: We couldn’t do it. And this was with a better bike. We had better bikes the second time around.

Martin Krieg: So, what’s the closest to you — closest record to you now for the race? Six days?

Tim Brummer: There’s a team of guys on upright bikes, the Kern Wheelmen, from California, that did it five days eight hours.

Martin Krieg: Whoa. Whoa.

Tim Brummer: So, we’re seven hours faster ahead of the upright bike guys.

Martin Krieg: An upright team. Oh, my god.

Tim Brummer: Yeah. Now, those are strong riders, too.

Martin Krieg: Uh-huh. Geez, how many — the — the four-man team?

Tim Bummer: Right, exactly. It’s four-man team. You’re riding nonstop 24 hours. And each guy is gonna ride with you. They had the advantage when the Kern Wheelmen did it; the rules had changed a little bit, and they were smarter as far as tactics. When we set our record, it’s the first time anybody had ever done it, so we’re kind of learning where as we were going along.

What the Kern Wheelmen were doing was — they might have been biking only for 20 or 30 minutes at a time for each guy to make switch. And they could do that because the rules had changed and they were able to do what’s called a rolling exchange, which have two guys on the bike at the same time. When we did it, they made us stop the bike before the next guy could go.

Martin Krieg: Oh, wow.

Tim Brummer: Yeah. So they had some big advantages, too.

Martin Krieg: Do you think you’ll ever race RAAM again?

Tim Brummer: Yeah. We do. We’ll see.

Martin Krieg: You are planning for — planning to do it?

Tim Brummer: Well, I’m not actively planning right now, but, there’s always the possibility, you know … if I can see a way to go on under five days …

Martin Krieg: Hmm.

Tim Brummer: And the thing about RAAM is it costs a lot of money.

Martin Krieg: Right. Right.

Tim Brummer: That’s the biggest issue you got to solve.

Martin Krieg: Sell a lot of bikes. What records besides RAAM do you hold for speed?

Tim Brummer: Anymore I think that’s it.

Martin Krieg: That’s it?

Tim Brummer: Yeah. I mean, you know, in the past we would set a lot of top speed records …

Martin Krieg: And so — I know what your answer’s gonna be in this question but I’ll ask for the uh, people that are listening. Uh —

Tim Brummer: Okay.

Martin Krieg: So, it seems like everyone — the records are all being set by uh, Bacchettas or Cruzbikes. Is your bike faster or slower?

Tim Brummer: I don’t know what records were set to start with unless it’s like a city to city or cross-state or something, but uh actually, you know, if you want to talk about those kind — we do hold records like Seattle to Portland: 7.5 hours. And then San Francisco to Los Angeles: 18 hours.

Martin Krieg: Hmm.

Tim Brummer: I think the biggest thing about setting records is the rider, you know. So, you can’t really compare bike to bike unless it’s the same guy riding it.

Martin Krieg: I guess what needs to be done I think is — and — I need to ask the questions differently. You once told me if you invested your money in a racing team instead of engineering, then you’d still be seen as a big dog on the racing block. Um, can you not divide up your dollars so you can keep your name on the racing front burner? Or would that compromises designs like your highly regarded carbon cranks and your front wheel drive trike that industry insiders have been buzzing about for years. Uh, is that why you’re not putting money into racing anymore?

Tim Brummer: To tell you the truth it’s kind of some personal issues: Ex-wife and lawyers and that kind of stuff.

Martin Krieg: Hmm, okay, that stuff.

Tim Brummer: That’s why.

Martin Krieg: Okay.

Tim Brummer: I got a lot other people taking my money, so —

Martin Krieg: Hmm, okay. But — so if you had some extra — extra cash, you’d love to be back in racing.

Tim Brummer: Oh, absolutely. Yes.

Martin Krieg: Letting people see how fast your bikes are? So, will you say yours is the fastest recumbent out there still, production machine?

Tim Brummer: I’m not sure to be honest because there’s some low racers, made in Europe.

Martin Krieg: Oh, low racers. Okay.

Tim Brummer: Yeah, some low racers and they’re production and you can buy them.

Martin Krieg: Uh-hmm.

Tim Brummer: The problem with those are you’re kind of limited in where you can ride them at and they’re not very practical.

Martin Krieg: Well, you used to have a low racer —

Tim Brummer: You know, our bikes you can ride them around town and —

Martin Krieg: Uh-huh. So okay. Is your bike faster than Bacchetta, faster than a Cruzbike?

Tim Brummer: Well, our mid-racers are, yes.

Martin Krieg: Your what now?

Tim Brummer: The mid-racer.

Martin Krieg: Uh-hmm.

Tim Brummer: Our mid-racer with — with the carbon seat where you lay the rider back. Basically, it’s the same position which Bacchetta has. Again, you know, it’s going todepend on the rider, but it’s at least as fast as Bacchetta, and you know, they climb better, too. So, even if it’s the same speed on the flat, you’re going to get a little faster on the climb. And they handle a little better on the down hills, too. So, that’s where you make up some speed.

Martin Krieg: So, what do you call that bike again, Tim?

Tim Brummer: Uh, mid-racer.

Martin Krieg: A mid-racer. So —

Tim Brummer: Yeah.

Martin Krieg: So, is — like your F40 and your uh —

Tim Brummer: That’s faster. That’s faster than the Bacchetta.

Martin Krieg: Yeah. Is the F-40 the one — that has the fairing?

Tim Brummer: Right, the full fairing on it.

Martin Krieg: Okay. How about — what is it called when it doesn’t have the fairing on it? P-38?

Tim Brummer: Right, we have the P-38 which is steel frame. And R-84 which is carbon frame.

Martin Krieg: So, the R-84 or the P-38, are those compared with the Bacchetta? Speed-wise?

Tim Brummer: When they have the carbon seat on there — when we put that carbon seat on there, then we call that a mid racer, because you lean back —

Martin Krieg: Oh.

Tim Brummer: — the rider’s gonna lean back a lot more,…

Martin Krieg: Okay.

Tim Brummer: — and those are the ones that like I said before we have a smaller wheel on the back. So that makes you faster.

Martin Krieg: Ah. So, these guys you see cruising around — with their — with their uh, rear hindquarters three, four feet off the ground, um — They’re — they’re actually — uh, there’s more wind turbulence underneath their fannies because they get the higher wheels than on a bike like yoirs?

Tim Brummer: Well, yeah. You got big wheels down there, you’ve got the frame down there — chains, all that stuff. So, it’s not the rider that’s slowing it down, it’s the wheels and the frame. So on our bikes, you know, we’ve got the small wheels, we’ve got the frames tucked up behind the rider or right underneath… That’s the stuff that makes ours a little bit faster just because we reduced the wheel and the frame drag.

Martin Krieg: So, by virtue of the fact that you got smaller wheels, you’re a faster machine —

Tim Brummer: Exactly. That allows us to do other things and this makes it faster, yeah.

Martin Krieg: Hmm, such as? The seat —

Tim Brummer: Well, like I was saying, getting the rider closer to the frame, and the frame behind the rider, and the chain, that kind of —

Martin Krieg: Wow. Wow. Okay. Well, it seems like it answers lots of questions that uh, um, that I’ve had in my mind. I’m sure a lot theirs —

Tim Brummer: I think that people buy the Bacchettas and bikes like that just because they’re used to seeing the road bikes, they have two big wheels — oh, those road bikes are fast because it’s got two big wheels, so the Bacchetta must be fast too or, you know, that’s what I’m — I’m used to seeing. It’s essentially all about images. It’s not about scientific results. So, just in their minds it’s fast because it’s got a bigger wheel, because that’s what the road bike used. Well, the only reason the road bike uses it is (laughs) because the UCI says they have to.

If they could they would use smaller wheels.

Martin Krieg: Hmm, God, wow. Okay. So, that — that’s something I never knew. I never knew that the ….

Tim Brummer: Well, I think it was about 10, 15 years ago the UCI banned the smaller wheels. They said, You have to use 700C wheels. And they’re very restrictive now on the bike design. It has to be the diamond frame and the tubes can only be of certain size. They can’t have an aerodynamic tubing. It’s very restrictive.

Martin Krieg: I knew about the Olympic decision. I knew that they extricated the smaller front wheel bike, the funny bike, from the equation — racing equation. I didn’t know that they also banned two — two equal sized smaller wheels as well …

Tim Brummer: Oh, yeah. Yeah. Yeah.

Martin Krieg: Geez. Oh, boy.

Tim Brummer: You know, all that stuff — I mean all there’s a lot of different frame designs, smaller wheels on the upright bike that make them go faster — and those have been banned because of the way the rules are written up. Supposedly the philosophy of the UCI is they want the competition to be between the riders and not between the bicycles or the bike engineers.

Martin Krieg: Right. Which kind of makes sense.

Tim Brummer: And then what happens is now it’s a competition between doctors and drugs. Like Lance Armstrong, you know —

Martin Krieg: Right.

Tim Brummer: — who can cheat and use —

Martin Krieg: Right, right.

Tim Brummer: — what drugs can we use, you know. So, they just switched, you know, who they’re competing against.

Martin Krieg: Right. And — I’m sure they’re afraid there are still drugs in that industry.

Tim Brummer: Oh well, yeah. I’m sure there is. Now — I mean it’s been like that ever since the race started —

Martin Krieg: Yeah. Whoever’s got the best detecting — medical detecting machines.

Tim Brummer: Right. Well, we got the best doctors that can get around the drug test.

Martin Krieg: Right, right. Yeah. Wow. Wow. You know, Gardner Martin of Easy Racers, he always had these crude roll-down tests to compare his machines against others, you know. And — essentially that worked kind of pretty much in the industry to demonstrate that he had speedy machines.

Um, being an engineer um, yourself, do you have any engineering studies besides Chet Kyle’s that uh, prove that wheel diameters within reasonable limits — have nothing to do with speed? Do you have any other studies besides Chet Kyle’s stuff?

Tim Brummer: Like I said we’ve done our own …

Martin Krieg: Uh-hmm…

Tim Brummer: — that’s not published, you know, just we did it here in house. Yeah, I think some other people have done these — these rolling resistance tests on wheels and wind resistance on wheels. I think there’s some out there, I just haven’t seen it.

Martin Krieg: Hmm. Okay.

Tim Brummer: And I think I saw some people in Germany were doing that. They were doing it for tricycle wheels and tires.

Martin Krieg: A tricycle ……

Tim Brummer: For the same reason, because on a tricycle — it’s better to have the smaller wheels in the front.

Martin Krieg: Uh-hmm. Hmm. Okay. Wow. Well, I guess that’s uh — that answers lots of questions I have. And I hope it answers a lot of — lots of questions that the listener has, and —

Tim Brummer: Okay.

Martin Krieg: — in sum, is there anything else you’d like to add?

Tim Brummer: No, that’s about it. And hopefully I can get my my personal situation straightened out here soon —

Martin Krieg: Wow. Okay, well jeez, Tim, it’s really, really great learning uh — some fascinating information from you about all this stuff. So, I feel blessed you took some time for us today. Um, I — I guess until next time. Thanks, Tim.

Tim Brummer: Well, I appreciate you taking the time to — to put this out there on the ‘net. It’s a lot of great information nobody’s really asked before. And you know, I appreciate everything you’re doing. You’re a great ambassador for cycling in general, and recumbents in particular, and hopefully, together we can make the world a whole much better place.

Martin Krieg: Tim, thanks so much, man. Wow.

Tim Brummer: All right. Thank you.

Martin Krieg: Okay, we’ll talk sometime soon, man. talk to you down the road. Take care, guy.

Tim Brummer: You, too.

Martin Krieg: Bye-bye. That wraps up another edition of the National Bicycle Greenway ‘s Mountain Movers podcast series. We hope you enjoyed it. This has been NBG Director and Awake Again author Martin Krieg. For more info about the NBG or to access this podcast in the future and to hear other shakers and movers that we’ve interviewed, go to BikeRoute.com.

Source: BikeRoute.com