Question about downhill riding.

Assuming you have no brakes, What is the best combination of wheel size and crank size to make it easiest to ride downhill.

TOO LITTLE INFO SO I MAKE BIG - Dr. Sbaitso

Road or muni? What other features on the overall track you’ll be riding? What steepness? Steady hill or varying slope? Will there be bumps and rocks and roots and tigers and bears (oh my)?

In general the answer is “as close (to 1:1) a ratio of crank length to wheel size as you can manage comfortably”, but that’s considering ONLY hill braking and nothing else. In practice, it seems that the “best” anything on a unicyle is a highly subjective dance between a handful of different interrelated factors at once, so actual helpful advice will require much more input :slight_smile:

billnye
John M

It will be Muni, on a dirt track with roots and stones. The descents are mainly of uniform gradient. Im hoping to get into muni and was wondering the best wheel size and crank length to make the descents more controlled.

Hey Robert, glad to see you joined our Uni community! There just so many variables, and it depends on many factors, such as your level of fitness, what type of terrain, just how steep and over what distance. Generally though, the smaller the wheel diameter and longer the cranks, the more leverage and torque you will have. For MUni-I have a KH 24"- I use 150mm cranks and love the challenge of steep climbs over long distances.

Many riders prefer 165’s and some even use 175’s, so it’s personal preference. As for a brake, I use it only rarely if I’m going down a particularly steep section, but I always try to use back pressure first, as it just makes you stronger as well. A brake can definitely come in handy though, and my Maggies have been used in some really tough DH conditions.

For “Coker Muni” I usually use 150mm cranks, but I bent mine doing a 4’ drop, so my backups are 165’s, which are still good for riding a 36er off road, where you will be doing some serious climbing, and you can still ride it a lot faster than a 24" with 150’s. For more XC off road cokering, I would use 127’s.

I highly recommend riding back up, also. Then you don’t need a shuttle driver (or taxi)! :slight_smile:

Of course, if the trail allows, it’s always better to start, and finish, at the bottom.

There are two ways to ride down a hill: keep it under tight control, or just go for it.

If you want to keep it under tight control, then you need the best leverage you can get - which is longish cranks and a smallish wheel.

If you want to just go for it, there is something to be said for slightly shorter cranks so you can keep it smooth and fast.

Generally, it is not possible to change your mind half way down if you start off by just going for it!

Another consideration is pedal strike - long cranks and small wheel means that your pedals are more likely to strike the edges of ruts, or isolated stumps or boulders. A pedal strike can be really irritating, and you may have several seconds in which to reflect on your mistake before you hit the ground and the pain starts.

Thanks! My 20’ has 127 cranks which might be making the descents a bit harder.

The default size for MUni is 24x3", and unless you have some unusual constraint, that’s probably what you should be riding for rocky, rooty downhills. The general trend has been towards shorter cranks; the accepted wisdom used to be that you wanted 165-170mm cranks for steep downhills, but now the bulk of the population is riding 150mm or even shorter on 24" wheels. KH is pushing 137mm. You wouldn’t want to go lower than 137mm without adding a brake.

Your 20" is OK for bouncing but not for rolling; trials tires usually have poor traction, and the small wheel can’t roll over much.

24 with 150mm is my way to go and just keep it rolling :wink: Fast is fun :smiley:

There a couple things to consider in choosing downhill crank length:

How fast you can spin
The slope and run out
Your leg strength
Your ability

I started on a 26 x 3 with 170’s, dropped to 165’s after riding novice single track. Then I went to a 24 x 3 and rode 165’s, then I got a 29er and dropped to 150’s. When I went back to a 24 x 3 I rode 150’s. In each drop I did have to adjust to having less braking power, but at the same time I was increasing my leg strength, spin rate, and ability.

So, now I ride 150’s and can pretty much do anything I have the nerve to do, but I am getting some 160’s for my new 26" XC machine :slight_smile:

If you learn to ride with 150’s, you’ll get used to it after a time, but longer cranks do provide more braking power as well as climbing power, BUT you lose spin rate and you’ll have more leg motion for each rotation, so more to manage.

If you’re a new muni rider on a 24 x 3, I’d get some 150’s and just learn to ride them, it worked for me and my son, also most riders use 150’s because they are a nice balance netween too short and too long.

As for what KH uses, well that’s just plain silly, we all know his underwear have a big red S emblazed on the front and back.

Hey :angry: , I’m not KH and I use 125’s on a 24 x 3 for muni.:smiley:

Checked your underwear recently for a huge red S ? :smiley:

Yeah, it’s not there.

If you have to ask, you aren’t riding trails steep enough to justify 165 or 170mm cranks. For muni, you want the shortest cranks you can comfortably ride, for the sake of improving efficiency, speed, smoothness, and reducing pedal strikes. A 24x3" or 26x2.6" tire on 150mm (or 137mm as you improve) cranks will serve you fine. You will know if you ever ride a trail where your cranks are too short.

Translation: Your trails are flatter than a frozen pond, post-zamboni. Congratulations. True bragging rights.

whoops, the above was rude. I apologize.

“Roots and stones” isn’t really descriptive enough to limit the discussion. Are there big drops? Are there a lot of natural trials like features? I think some trails with “roots and stones” are great fun on a 36er with 125s.

I have ridden some big hills in Berkley and Santa Cruz, CA when I was there last winter and that was on 125’s. Ask Nathan Hoover or John Foss if you really care. Also, Beau Hoover also uses 125’s on his muni, and he lives in CA, only 30 mins from Santa Cruz, not what you would call flat:D. (Thanks for the appology-ish though)

Just tell him roots and stones may break my bones but words will never hurt me.:stuck_out_tongue:

+1 :d

+1
but do please note, I have maggies.