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I've been riding a 1980's-era (unsuspended) Specialized MTB with slick tires on the road for many years, and recently got a Marin trail bike with a Suntour SR front suspension. I thought it would make the ride better on bumpy roads with pot holes and cracks, but it seems to take more effort in getting up to speed than I assumed it would.

Do shocks/front suspension just get in the way of riding on the road? Or is it just a matter of getting more expensive/better shocks?

I've changed the chain and checked that the tires are spinning freely, but I still can't quite figure out what's holding this bike back other than the shocks taking energy away from compressing on each pedaling stroke.

Thanks for reading. Please help guide me out of this mess, thanks!

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    I found that heavier tires (i.e. Marathon Plus) feel like better suspension, for commuting on a street with pot-holes. Counter-intuitively I found them faster because I felt they were bomb-proof and so I didn't slow down before hitting a rough patch like I did before with a lighter tire.
    – ChrisW
    Jun 20, 2022 at 19:44
  • Welcome to Bike Exchange Cadence. I added a concise answer to the group below.
    – Ted Hohl
    Jun 23, 2022 at 4:46

7 Answers 7

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A common misconception is that riders associate suspension with comfort. The reality is that suspension is not there to make your bike more comfortable.

The purpose of suspension is to allow the wheel to track rough terrain, affording you greater control, not comfort. If the wheel is in contact with the ground, then you can steer and you can brake. If the wheel bounces up off the ground then you can do neither. (You may also fatigue more quickly, so it does help with comfort in it's way, but only in a meaningful way on rough ground)

When on the road, your wheels will very rarely lose contact with the ground, save for dropping off a kerb or a major pot hole, and you're right in noticing that the forks will compress when you pedal/accelerate - this takes energy away from your pedalling that could be moving you forwards.

If you have knobbly tyres on instead of slicks, then you will very likely lose a lot of energy to the less efficient tyres too. These grip on loose surfaces, but on the road you wouldn't have been struggling for grip before as the surface is solid. That's another big loss of energy with no benefit.

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    I wouldn't call that a "misconception". Different things matter to different people. On a citybike I might just want to drive over cobblestone without the handlebar feeling like a jackhammer, but still never get anywhere close to losing control.
    – MaxD
    Jun 21, 2022 at 19:44
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    @AndyP Obviously this depends on the type of cobble. On that nasty spot in my city that has like 15x15cm cobbles with pretty domed tops and large gaps, the suspension does some serious work.
    – MaxD
    Jun 21, 2022 at 20:00
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    Even on serious pavé sectors on Paris-Roubaix GCN showed that a hard-tail mountain bike was faster than a cyclocross or road bike. So it is effective at least in that.
    – Vladimir F Героям слава
    Jun 21, 2022 at 20:02
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    This answer is nonsense. Comfort is a/the main reason to upgrade suspension or increase travel. This is true whether on rocky ground or just going over potholes. Losing control due to being bounced around is relevant at high speeds that are already avoided due to discomfort. The only exception is not noticing a large bump/obstacle
    – johnDanger
    Jun 21, 2022 at 20:20
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    @johnDanger You’ve got your correlation and causation mixed up there. Comfort (defined as reducing the magnitude of forces transmitted to the rider) is an inherent side effect of good suspension performance, but it is not the aim.
    – MaplePanda
    Jun 22, 2022 at 0:22
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A couple minor points not addressed above.

First, your tires provide a significant amount of suspension. I don't know how many riders inflate their tires to the maximum pressure on the sidewall. However, this will be a lot less comfortable and it is also likely to be slower. People who study rolling resistance have shown that on real-world surfaces, there is an optimum pressure for each tire that minimizes rolling resistance, and it's lower than many people think (on extremely smooth tracks like track cyclists use, higher pressure does indeed always equal lower rolling resistance). People on paved surfaces don't need suspension. For that matter, cyclists take rigid bikes (i.e. no suspension) onto dirt roads and light gravel all the time.

Second, suspension forks are expensive, and they require maintenance, which is expensive in either your time or your money. At a fixed price point, having a suspension fork detracts from other components. Most newer riders don't realize this, and are essentially demanding capabilities that they don't need. In fact, if taken to the extreme, the suspension will fail entirely, leaving you with dead weight on the frame (although I guess at least your fork won't bob when pedaling).

Third, suspension forks may come with lockouts, which reduce energy-sapping bobbing behavior on the road. However, lockouts tend to be present only on pricier forks.

Fourth, to a point that @AndyP raised: gravel suspension forks are a niche market, and those systems are indeed designed to damp small amplitude bumps rather than for big hits. However, these are rare, and tend to be costlier.

Fifth, if you do want to damp vibrations for comfort, there are suspension seatposts and stems available. The couple of designs that I'm aware of (which is not all of them!) don't require maintenance. However, their pivot points and elastomers will eventually wear out. The elastomers will be replaceable if the originating company is still running and if it kept stock. The pivot points tend not to be repairable. So, while I don't know the potential lifespan of these items, it should be long but not infinite. The ones I'm aware of are relatively expensive designs (e.g. Redshift's stem and seatpost, Cane Creek's seatpost), and cheaper stems and seatposts might not last as long.

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    Yes, the lauf fork for sure is designed with this in mind. I'm not sure about the ones from other manufacturers that are basically just very short travel regular forks that still will still suffer from 'stiction'
    – Andy P
    Jun 20, 2022 at 19:37
  • This "optimum pressure" is above that likely any MTB tire could stand, at 8 bar still declining. bicycles.stackexchange.com/questions/71994/… Or give your source otherwise.
    – nightrider
    Jun 20, 2022 at 20:29
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    @nightrider the breakpoint varies based on tyre volume, carcass suppleness, rider weight and surface roughness. I've never tried to experimentally find values myself, but from my experience it wouldn't surprise me at all if the breakpoint was between 30-40psi on a mountain bike tyre on a poor road surface.
    – Andy P
    Jun 20, 2022 at 21:00
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    @nightrider Here's an updated link to that blog post. Note that it documents the v-shaped relationship of CRR and pressure for road tires (23-28mm). The optimum pressure will be a lot lower for an MTB tire! silca.cc/blogs/silca/part-4b-rolling-resistance-and-impedance
    – Weiwen Ng
    Jun 21, 2022 at 19:32
  • It is a very good link, and I now upvote the answer due it. But it still shows that the optimal pressure is often close to 100 psi, over 6 bar, except very rough surface where the lowest they tested was the best.
    – nightrider
    Jun 22, 2022 at 4:34
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A suspension fork serves basically no purpose on the road and does very little to add to the comfort. Due to the design of most suspension forks they are excellent at absorbing large impacts, but quite poor for smaller high frequency impacts you may find riding on road or gravel.

Here are my answers to a couple of similar (but not duplicate) questions we have had recently to provide a little more information on this aspect of your question:

But to answer the second part of your question, it's very unlikely the suspension fork is what is making the bike slow. Since you've checked over the bike to look for actual mechanical issues, the most likely things making the bike slow are slow tyres or an inefficient position/geometry.

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I ride my MTB on the road a fair bit, as I ride to trails etc. in preference to driving. I also recently did a day with about 140km of road on my MTB (a Saracen hardtail, entry level) to get to 60km of gravel and rough stuff. Normally for road riding I'm on a tourer with no suspension and 32mm slicks.

I do lock out the forks for the road, but it doesn't make much difference on the flat, except when accelerating. On climbs you can both feel and see the forks compress with every stomp on the pedals.

A far bigger difference comes from the choice of tyres. I have 2 sets - a pair of WTB Nano, almost a gravel tyre, and a set with the front a Nobby Nic and the back a Rapid Rob. The latter set is much better for mud and wet rock, but pedalling on tarmac feels like I'm dragging along a sandbag in comparison to the Nanos. The centreline stripe seems to make a big difference. For the mixed surface ride I did recently, I pumped them up to 90% of the rated max pressure; normally I let a bit out when I get to the trails. I'm pretty heavy, and was carrying a bit of stuff with me.

If you're running the stock tyres on the Marin, they'll be taking much more effort than the slicks you were used to.

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Many forks have a switch to disable the suspension on a good road and then it should not impact your performance, except additional weight maybe.

I am under impression that the front and especially seat post suspension results the more comfortable ride over uneven gravel road, but in my case this is E-bike so any loss in performance is likely just transparently compensated by the controller.

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Generally, front suspension will have a pretty trivial, minor negative impact when riding on pavement. I stress the trivial, and this is when one is just cruising on flat terrain.

The game changes a bit when climbing or when standing on the pedals (or both). Your arms take on a more active role when in these modes, leveraging the handlebars against the pedaling motion to add upper body muscles more into the power output. When your arms are pogoing the front suspension instead of adding to forward motion of the bike, some efficiency is lost.

A case for this is easily made by the added capability to lock out front suspension on almost every modern suspension fork. If there was not a valid reason to lock it out, then the lockout feature would not be added.

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  • If someone is shallow enough to down-vote a concise and good answer, please be man enough to explain in a comment, or better defend your case with data.
    – Ted Hohl
    Jun 23, 2022 at 15:58
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    Apparently at least one person is offended that your answer points out that one of the most common myths in cycling is indeed a myth. If it makes you feel any better, the rest of us that made similar answers also got downvoted
    – Andy P
    Jun 23, 2022 at 21:21
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The simple answer is yes,a lot of the pedal power and speed momentum will be absorbed by suspension and lost.

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    Not sure why this is getting downvoted - this IS the simple answer, one that you'd get full credit for on a college physics final by stating it's intuitively obvious. Good answers don't have to be long-winded.
    – Andrew Henle
    Jun 21, 2022 at 12:31
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    @AndrewHenle ...on a college physics final where you also get full credit for describing the bike's movement with special relativity? –Sure, technically it's correct, the speed will increase your mass and dilate time – but by “a lot”? Hardly. Unless you take the bike to a planet in orbit around a black hole... Likewise, a suspension fork does technically always seep a bit power, but it can in most situations be kept to a small amount, almost insignificant compared to aero- and tyre losses. Only a soft but rebound-damped fork, ridden without lockout standing up, will take a lot of power.
    – leftaroundabout
    Jun 21, 2022 at 13:43
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    @leftaroundabout Quit being absurd. It is intuitively obvious that shock absorbers absorb, and it's also intuitively obvious that what they absorb is energy, and it follows that since the only source of energy powering a bicycle is the rider, anything that absorbs energy must slow the bike down. All of which is nicely summarized in this answer. You could even say your long-winded ridiculous comment even made my point about uselessly long-winded posts. Q.E.D.
    – Andrew Henle
    Jun 21, 2022 at 14:23
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    That's perhaps intuitively obvious, but it's not true. First: shock absorbers absorb... shock, in fact – but they don't, at least in principle, have to absorb energy. (To filter small bumps an undamped spring is enough, operated above the resonance frequency.) That a bit theoretical because suspension fork generally dissipate energy even at the lower damper settings (not sure about Lauf). But more importantly, the fork only absorbs anything if it actually gets to compress-and-expand. However, a smooth clipped-in pedal stroke while in the saddle barely causes such movement even at high watts.
    – leftaroundabout
    Jun 21, 2022 at 14:32
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    @AndrewHenle I also downvoted for the use of the phrase 'a lot'. If I rode my MTB on a flat road at 200W i'd be surprised if the fork absorbed more than 1W. On a typical fork at a typical pressures it basically does nothing unless you are braking hard (brake dive) or climbing out of the saddle. You probably lose 10x more power to the terrible aerodynamics of a suspension fork than you do to suspension losses
    – Andy P
    Jun 21, 2022 at 19:43

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