Effect of Flex on Braking (36'er)?

Hey fellow unicyclists,

Just a quick question. It seems that once in a while, I stumble across a post where someone talks about how riding a 36’er uphill can cause the frame/wheel to flex. It seems that because some of these unicycles have rim brakes, the flex causes the brakes to involuntarily rub against the rim, which can slow or stop the unicycle. But most of these comments seem to be from a couple of years ago.

My question is whether the newer 36’ers still face similar problems. If so, how did you guys solve them? The specific models I am looking at are the Nimbus Titan, Coker Big One, and Coker V2. The other ones are really out of my budget.

Also, how steep a hill can people ride their 36’ers up? I don’t mean killing yourself to make a new achievement, but just for regular commuting (Salt Lake City terrain?)

D. Y.

Hi D.Y.,

Although I can’t speak to the relative flex of the three 36er models you are considering, I figured I’d take on your questions because in the past I have commuted to work in Salt Lake City’s Research Park on an older (2010) double-hoop Nimbus Nightrider equipped with Magura rim brakes – and I never had a problem with the brakes rubbing.

Even though many folks have experienced the annoyance of rim brake rubbing during steep climbs on a 36er, I suspect the reason that I never experienced it during my commutes was that I was either not generating the level of torque that causes the problem, or the hills I was able to ride up didn’t require that much pressure on the pedals, even though my Nightrider frame is pretty flexible.

My (former) commute of about 6.5 miles brought me from South of Parley’s Canyon on Wasatch Blvd., to the North across the bike trail bridges spanning I-80, continuing along Wasatch Blvd. (to avoid the traffic on Foothill Drive) all the way through Bonneville Golf course, behind the Hogle Zoo, down Crestview to Emigration Canyon Rd./Sunnyside Ave., down Sunnyside Ave. to Arapeen Dr., and up Chipeta Way past ARUP to the top of Research Park. The most significant hills on this morning route are (1) the climb to the top of the bridges over I-80, (2) the climb up Wasatch Blvd. through the Golf Course and behind the Zoo, and the final climb up Chipeta Way. The hardest of these hills for me was #2. The first few times I rode this route, I had to walk the last part of Wasatch. Eventually, as I got stronger and more comfortable on the big wheel, I was able to ride it all. I also usually had to rest and catch my breath on the bridge over I-80 after hill #1, and I found that the best way for me to tackle the final climb was to “stair step” up through the ARUP parking lot, rather than ride straight up hill #3.

I hope that gives you some idea of what is possible/reasonable for a guy who, at that time, was in his early 50s and had limited “saddle time” on a 36er. Sadly, I had to start working downtown just over a year ago, and the commute of ~10 miles with significant (~500 ft) elevation drop effectively ended my 36er commuting days. The ride to work wouldn’t be that bad, but the ride home would be too much, especially with me now having to work 9+ hr days, on average. Plus, the objective hazards of the commute to Research Park were acceptable because of the route. In contrast, commuting on unis through downtown SLC traffic presents an unacceptably high risk of injury or death to me. (I’ve lost a friend to a commuting accident in Washington, D.C. in the past, and b*ke riders are hit and killed in SLC regularly.)

BTW, I’m not certain of the grades of those hills I used to encounter on my commute, but I suspect the steepest one on the order of 8%. I’ve attempted 11% grades on my 36er, and can only manage them if they are short. Results may vary, especially for younger, stronger riders; and the hills do get easier with experience.

If you have further questions about riding in SLC, send me a PM, and come out and join us for Muni some time.


UPD in Utah

(a.k.a. Bert)

I forgot to mention…

I forgot to mention that my Nightrider came equipped with 150 mm cranks, but I found I needed the extra torque provided by 165 mm cranks to climb those hills and have the rapid response control needed for commuting. Switching to 165s increased my confidence and climbing ability substantially. The also helped with freemounting.

Thanks for the detailed info, right in SLC, too! It’s a shame that riding to work is so dangerous. I was looking forward to commuting on a 36’er. Thanks for the offer to ride together, but due to a knee injury, I’ll have to sort that out first:(. But I’ll let you know when I get better. Thanks again.

I remember having a lot of problems with flex on my Nightrider. It wasn’t so bad that it would stop the wheel. My old steel Coker frame was stiffer, and had no problems, but the same wheel on the Nightider would hit the brakes on uphill grades. And I should say only when I was starting. If I was already moving it didn’t seem to be a big problem.

I put a disc brake on it, and never had a problem again.

The problems I’ve had with frame flex have all been with Magura equipped unis. The stock HS33 hydraulics don’t have a lot of extra travel. That being said, I’ve had OK luck with a Hunter and a KH. On another KH I have problems with the brakes catching. I think this was due to the wheel build not quite being as solid as I liked as my spokes were just a tad bit too long and I couldn’t get the tension where I wanted it.

Regarding the unis you listed, none of them use the Magura rim brakes. The Titan uses a caliper brake which is probably the best bet as the pads have a fair amount of travel when the lever is pulled. It’s a stellar value of a unicycle, especially with the Nightrider tire spec.

As far as the newer unis addressing the problems, not a whole lot has changed in the basic design. The one thing that has is that the move to disc brakes essentially has essentially eliminated the issue of frame flex.

For climbing, my daily commute entails a brick hill climb of 7% or so. Not a problem at all on 125s even in the dark. I prefer shorter cranks (100s or 110s) for ungeared riding of distances longer than a few miles. As far as what can be climbed on those, I’ve been over 10%. The hill one street over is 15%+ and I regularly climb it on 150s without extreme difficulty.

This makes a lot of sense to me. I had a caliper brake on my Coker, and Maggies on the Nightrider. Maybe the Coker wasn’t stiffer at all it was just the brake itself.

Don’t know about Salt Lake, but after a month or so on my 36 I was comfortable going up some pretty steep hills on the 127mm holes. Granted the hills I ride on my commute are not terribly long, but a few of them are steep and I just stand up on the thing when I need to. I’m on an Oracle, so not sure how the weight compares to the others. I am pretty sure the muni and flatland I’ve done has helped me with my abilities on the 36 too.

I bet unigeezer or aspenmike would have something useful to say here.

In general, unless you are doing really long steep hills I would stick with a 36 for any distance. You can always go with longer cranks, like maybe 150s.

Thanks for all the help. It’s good to hear about the recommendations for the Titan. Thanks guys!

The big difference is that less people are using Magura rim brakes for 36ers anymore.

Maguras are without a doubt the best rim brakes I have ever used but if a rim is deflected into them they cannot move out of the way like a V or calliper brake and can cause significant braking force. The relatively low travel of the pads intensifies the problem by allowing very little movement before contact.

I have used Maguras on a Nimbus Nightrider frame and KH. I got rubbing on both but considerably less on the KH. When I got one of the first Mountain Uni Disk brake setups I was so happy with the resulting brake that I ground the Magura mounts off my KH36 frame figuring I would never want to use them again. I sort of regret that now as they would have been good mounting points for a rack.