MTB Oppo Opinions: Belt Drive

"benjrblant" (benjblant)
08/07/2019 at 17:11 • Filed to: the spot doesn't have a tag yet, mtb

Looking at picking up a Spot Rocker Ti single speed MTB frame and considering running a belt drive with it. This will be for trails around the area, nothing too extreme, nothing too long, and definitely not for bikepacking.

Apart from the limited availability of components for it, is there a really good reason not to run this?

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Front (39-70t) and rear (20-34t) sprockets are available thru !!!error: Indecipherable SUB-paragraph formatting!!! , as are belts in varying lengths.

DISCUSSION (39)

MrDakka > benjrblant
08/07/2019 at 17:20

https://en.m.wikipedia.org/wiki/Shaft-driven_bicycle

RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars > benjrblant
08/07/2019 at 17:22

Pardon the possibly snarky sounding question (as I don’t mean it to be at all), but....why?

Is there an advantageous reason to select a single-speed belt drive over a multi-speed or single speed chain drive? I would think the chain system would be more reliable and lower maintenance as I’d think a chain would last a lot longer than a belt?

HFV has no HFV. But somehow has 2 motorcycles > benjrblant
08/07/2019 at 17:23

I’m a big fan of gates belt drives. Idk how it’ll hold up to mountain biking tho. Should be fin tho.

Are you going to run an internal gear hub as well. I know shimano makes a 7 speed for the belt drive

SPAMBot - Horse Doctor > benjrblant
08/07/2019 at 17:24

I hear it’s an engine out procedure to replace the belt and you need to do it every 200 miles or 6 months, whichever comes first ;)

McMike > benjrblant
08/07/2019 at 17:26

Shouldn’t be an an issue, since most belt services aren’t until 90-110K miles.

benjrblant > RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars
08/07/2019 at 17:27

SS is much lighter, and belt drive is a near-zero maintenance system. Not that I’m afraid of maintenance as I’ve got most of a bike shop in my apartment, but it’s sorta quirky and weird. You know those people that drive weird cars for the sake of driving weird cars? Yeah.

benjrblant > HFV has no HFV. But somehow has 2 motorcycles
08/07/2019 at 17:28

No geared hub. This will be a SS build, either a chain or a belt.

gettingoldercarguy > benjrblant
08/07/2019 at 17:31

I thought I saw Saab on that part somewhere.

If only EssExTee could be so grossly incandescent > benjrblant
08/07/2019 at 17:32

Not that I'm at all knowledgeable about this, but does a heavy chain produce any sort of flywheel effect? I imagine pedaling will feel much different with a belt.

benjrblant > McMike
08/07/2019 at 17:32

I’ll be long dead before I hit 100k miles on a single bike, so sounds like we’re golden!

atfsgeoff > benjrblant
08/07/2019 at 17:32

Don’t own one yet but my next bike will probably be a Gates belt drive and Pinion gearbox.

atfsgeoff > RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars
08/07/2019 at 17:33

Belts last about 2 or 3 times longer than chains on bicycles.

4kc > benjrblant
08/07/2019 at 17:33

Most testing shows belt drives are a significantly more inefficient, mostly due to the tension required on the belts I believe? Think it can be like 30% which is pretty noticeable imo

It was much more of a pain to re-mount a belt drive wheel 10 years ago when I was a mechanic but things might have gotten easier.

benjrblant > If only EssExTee could be so grossly incandescent
08/07/2019 at 17:34

Not much flywheel effect from a chain because of its long and mostly linear travel path , you’d get more of a flywheel effect from having a massive 50t cassette in the back as is common on more bikes. However, these components only spin when you pedal (not coasting) so there’s not really any gain to be had here.

someoneatacura > benjrblant
08/07/2019 at 17:36

You’ll have to cut the frame to install it, something a lot of people don’t realize. Otherwise I ’ve heard they’re good. I would rather stick with a chain, especially if I want to be able to self service incise of a mishap .

AMGtech - now with more recalls! > RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars
08/07/2019 at 17:36

Chains are very high maintenance. I have to clean and lube mine every other ride. I would love to not have to do that.

benjrblant > 4kc
08/07/2019 at 17:37

Yes, I’ve read about power losses as well, but I didn’t hear 30%. I recall seeing more like 1-5w which is negligible on a MTB.

Hadn’t considered how difficult it would be to mount the rear wheel. I worked in a shop some years ago and we had one belt drive bike. I don’t think I ever worked on it though.

FWIW, it looks like chainrings would limit me to a crankset with a 4x104mm BCD, which is becoming less common now.

benjrblant > someoneatacura
08/07/2019 at 17:38

Not in this instance, the Spot Rocker Ti has a split dropout to accommodate belts. It was designed this way and welded in Colorado.

AMGtech - now with more recalls! > benjrblant
08/07/2019 at 17:39

If I could have comparable ratios and at least 10 gears, I would be all over a belt drive. So much less work.

benjrblant > AMGtech - now with more recalls!
08/07/2019 at 17:41

But you can! It’ll only cost you $3k for a belt drive system and a Rohloff hub.
*Plus whatever money for your hardtail belt-compatible frame.

AMGtech - now with more recalls! > benjrblant
08/07/2019 at 17:43

Ouch. I haven't heard of that one. Way too much money. And hardtail... Boo. Not for the trails I ride and my aging body.

someoneatacura > benjrblant
08/07/2019 at 17:44

Oh good, yeah then you could go for it then. I mean, if you hate it you should be able to sell the kit easily enough right?

Ssfancyfresh > benjrblant
08/07/2019 at 17:47

That’s very cool. You should definitely do that. I ride single speed. I’ve always wanted to do a belt drive. Neat bike. Spendy though. $3800 frame only in 2012? Damn.

benjrblant > someoneatacura
08/07/2019 at 17:51

Maybe? I feel like it’s such a niche thing that I’d have a hard time selling it, even here. Dunno man!

benjrblant > Ssfancyfresh
08/07/2019 at 17:54

Back when Spot Brand was a small frame builder based in Golden that hadn’t sold out yet, they made a lot of cool and excellent bikes. The Rocker TI was primo at the time, hand built in CO, and they didn’t make all that many. I’m not sure if I’d equate it to a Moots, but it would’ve been damn close.

There’s a frame and Reba XX nearby for $1k, going to check it out later.

smobgirl > benjrblant
08/07/2019 at 17:56

I was obsessed with Spot bikes for years but I’m too poor and out of shape for a single speed. I’m excited to see what you think of it!

Highlander-Datsuns are Forever > benjrblant
08/07/2019 at 18:10

That would be a slick set up for a single speed.

SilentButNotReallyDeadly...killed by G/O Media > benjrblant
08/07/2019 at 18:30

Here’s my two cents. That’s a fine frame and you should definitely get it but I personally wouldn’t go with a Gates belt on it.

Primary reason is that belt drives on bikes are highly sensitive to the chain line. If the chain line is not absolutely dead straight then prepare for noise and wear.

Since this frame also has sliding drop outs this adds to the complexity of getting a dead straight chain line. It’s also titanium, thin and comely and the rear end will flex...again, it doesn’t help that chain line.

The only scenario where I'd consider a Gates on a bike like this was if it had a 142 rear axle that fits perfectly...but I'd still probably go with the chain....

benjrblant > SilentButNotReallyDeadly...killed by G/O Media
08/07/2019 at 18:35

All very good points. At present, the frame has the factory sliding dropouts, 135mm QR. These can easily be changed out for inserts that accept a 12x142 axle, but then I’d question how easy it would be to reinstall the belt with sufficient tension.

The more I think about belts, the cooler I think they are and the less I’d like to have one.

RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars > AMGtech - now with more recalls!
08/07/2019 at 19:48

I have literally never lubed or cleaned the chain on my mountain bike for like...15 years and it still works perfectly, lol.....probably would work BETTER if I did, but...haha!

RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars > atfsgeoff
08/07/2019 at 19:49

I guess it depends how often you use a bike? Mine is 20 years old and I’ve almost never lubed or greased the chain and it still works fine. Though, admittedly the gears need a little adjustment.

Ssfancyfresh > benjrblant
08/07/2019 at 19:50

Moots YBB was hot shit when i built my Klein Palomino.

Those were the days... of slightly questionable suspension geometries and dodgy engineering.

atfsgeoff > RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars
08/07/2019 at 20:08

Most people don’t put enough miles on their bike to wear out the chain and sprockets. They usually last about 5,000 to 6,000 miles.

benjrblant > Ssfancyfresh
08/07/2019 at 20:23

“what metal fatigue?"

sn4cktimes > benjrblant
08/07/2019 at 21:09

I have a Scott Sub with a belt and 7 speed Shimano hub gear. I really like the belt. It’s super quiet and doesn’t get my pants all dirty. Only thing I don’t like is the Presto valve tubes and skinny tires. I plan on changing both. The hub gear changes well, changes fast, and is generally very quiet and unobtrusive. Coupled with call iper style brakes my bike is pretty quiet.

AMGtech - now with more recalls! > RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars
08/07/2019 at 21:47

Mine gets dusty, sandy, muddy. Like real bad. Cleaning and lubricating it every few rides makes it shift like new again and keeps it quiet. If I don’t, shifting gets real bad and pedaling is real loud. Like loud enough to make you think something is wrong. These are just from one relatively short ride.

Kinja'd!!!

AMGtech - now with more recalls! > atfsgeoff
08/07/2019 at 21:48

Only riding pavement on sunny days makes a difference too. Riding singletrack in all weather takes a toll real fast.

SilentButNotReallyDeadly...killed by G/O Media > benjrblant
08/07/2019 at 21:58

Tensioning is easy enough using the positioning screws for the dropouts.

However, a word of warning about swapping to 142 thru axle dropouts, if the frame has been used then there is a good chance that you won’t be able to get the 142 dropouts to line up because of movement over time in the rear triangle...the Twinzer taught me this the hard way.

Belt drives are cool but I don't think I'd want one on a MTB.

benjrblant > SilentButNotReallyDeadly...killed by G/O Media
08/07/2019 at 22:28

I think you and a few others have convinced me to go chain for a 1x1.