AASQ #109: FSA focus on ultra-short cranks and tremendous compact gearing for gravel bikes


We all know, there’s no such factor as a silly query. However there are some questions you won’t wish to ask your native store or using buddies. AASQ is our weekly sequence the place we resolve your questions – severe or in any other case. This time we focus on extremely brief cranks and tremendous compact gearing for gravel using with the specialists at FSA! Hit the hyperlink on the backside of the put up to submit your personal query.

Thanks a lot to everybody who submitted inquiries to FSA for this week’s Ask A Silly Query. You guys requested some actually attention-grabbing, poignant questions on tremendous compact gearing and extremely brief cranks. John McKone and the crew from FSA Highway fielded, answering each single final one among them.

Every part from entrance derailleur adapters, crank arm size, tandem cranksets, 1x versus 2x, bikepacking-friendly gearing, MTB choices to modular cranksets is roofed herein. If anybody has any follow-up questions for FSA about their tremendous compact teams and extremely brief crank arms, pop them within the feedback. Get pleasure from!

Masters riders and folk who wish to climb large hills would admire the tremendous compact setup for his or her highway bikes. For the FSA smaller entrance sprockets and authentic 52/36 riveted derailleur tabs, what entrance derailleur mixture or extender goes to permit this?

FSA: We provide an adapter for this resolution. That is an extender designed to suit between the entrance derailleur and the entrance derailleur hanger. This may assist you to select a a lot smaller chainring configuration resembling Tremendous Compact and nonetheless keep optimum shifting.

A small entrance gear is nice for gravel using to get a decrease gear ratio with a better rear cassette. Nevertheless, basically, a smaller entrance ring isn’t one of the best for energy effectivity. An enormous gear is healthier than the internal small gear, normally. How a lot power switch loss might be anticipated compared to a identified compact like 50/34? By the way in which, I’ve your Energy Field Tremendous Compact to pair with my highway cassette. I used to run 52/36-11/42 however now it’s 46/40-11/28.

FSA: Agreed, typically. With such a big number of rider varieties who all have totally different backgrounds and using experiences, energy effectivity might be totally different from one rider to a different. Whereas some will wish to “energy” over a climb or part of highway/path, others could also be eager to clear it inside their limits.

Friction info carried out some nice testing round 6 years in the past. You possibly can obtain their full report right here. They discovered solely round a 0.5 Watt distinction switching between a 53 and 39 tooth chainring measurement, a 14T distinction.

A extra important contribution to friction is chain angle. Cross chaining can add as much as two Watts of drag. This implies deciding on the precise gearing and being sensible about shifting contribute important friction financial savings.

FSA Gossamer Pro alloy road cranks get super short & sub-compact, 2x road compact

As a result of our tremendous compact gearing offers a bigger distinction in CR measurement chances are you’ll discover it simpler to keep away from cross chaining offering friction financial savings over different gearing choices.

Do FSA make a tandem crankset anymore? I might like to replace our tandem from the older Gossamer triple crankset to a lighter weight double crankset. With the present vary of 11 pace cassettes, I really feel that I may do exactly advantageous with a double chainring setup and nonetheless have the identical gear vary as our present 10 pace triple chainring setup.

FSA: Sure, we now supply an SL-Okay carbon Tandem crankset with 2x gearing. This technique is out there in a 50/34 combo and is appropriate with each 10 and 11 pace drivetrains. Test it out on our ProShop right here

fsa-slk-tandem crankset rear 2x setup

If a rider switches to shorter crank arms, say from 170mm to 150mm, she or he might want to increase their saddle an equal quantity, which may imply the bike not suits correctly. Is that this usually thought of when deciding to make use of shorter arms?

FSA: That’s an incredible query and the easy fast reply could be to adapt the change in crank arm size to the seat top or presumably along with an adjustment in cleat stack top, relying on particulars of the match. An area skilled bike fitter could be an incredible place to begin that course of.

Do FSA have any plans to make bikepacking-suitable gears accessible off the shelf? I’ve an SL-Okay crankset however the 46×30 rings are nonetheless too extremely geared for if you’re carrying a load of tenting gear up lengthy steep grades. I used to be capable of take an MTB spider and put it on the arms to present me a extra bikepacking pleasant 38-24 combo however this wasn’t simple or low cost. It will be nice should you supplied alternate spiders for these cranks to make this simpler for patrons. Ditto for people who may wish to run a 1x arrange. Additionally, should you say “simply use an MTB crankset”… nicely then there’s the problem of Q-Issue and fewer than optimum chain traces.

FSA: For certain, the drop bar off-road class has been evolving over the previous few seasons and FSA has been adapting as we will. Ought to we construct a decrease vary than 46-30? Completely! We’re all the time getting new product out into the marketplace for riders to have extra selections. And we do supply 1x with our Gossamer sequence, though I wish to see that trickle upward to our high vary Okay-Pressure AGX cranks.


For gravel using, does a 50+mm chainline 1x entrance chainring trigger extra friction, put on and lack of powertrain effectivity when within the largest rear cogs?

FSA: Nice query. 1x has been the default MTB arrange for a while now with some gravel riders adopting this technique. With each gravel and MTB setups the 1x chainring is neither inboard nor outboard positioned, resembling on a 2x chainring system. The 1x chainring is positioned within the center, to higher deal with the rear cassette chainline adaptions wanted.

That is someplace round a 44-50mm chainline reference (heart of the underside bracket to the center of a 1x chainring). Like several system, 1x or 2x, the acute higher and decrease cassette sprockets will push that chainline to its restrict inflicting some further stress and, in the end, growing required energy (negligibly) in comparison with intermediate gears.

FSA Gossamer Pro alloy road cranks get super short & sub-compact, 1x

Ideally, a 2x system offers extra vary by way of a constructive chainline, resembling Tremendous Compact. As a result of gravel bikes usually have smaller tires, they will higher settle for narrower chainlines than MTBs. We provide just a few totally different 1x chainlines to swimsuit totally different wants relying on the precise software.

Why is bike gearing so stupidly excessive? I’ve (Shimano 11 pace) 11-28 and (FSA) 34/50. At 60 RPM within the lowest gear I’m using at 6 MPH – OK, though not likely low sufficient. At 100 RPM in high gear I’m going at 37 MPH – utterly unrealistic. Over 21-22 MPH, I’m most likely coasting (having nearly killed myself using up the hill in a excessive gear). My precise pace vary is 6-10 MPH up hill, 11-14 MPH on the flat, 15-20 MPH with the wind and as much as 25-27 MPH downhill; I dwell in a flat a part of the world. Gearing which might swimsuit me higher could be a 1:1 low gear and excessive sufficient to get to 25 MPH at 100 RPM. With my present 11 spd 11-28 that would wish a 28T chain ring. This yields an excellent compact, light-weight 1×11 arrange and offers me vary of gears which really matches my potential. If I may use a 12 spd cassette, I’d add a 16 tooth cog (reasonably than a 10T) to present tight ratios in the course of the vary. I really like bikes. I run an electronics engineering firm and will get 4-5′ aerials out of the efficiency bowl at Romford skate half after I was a child.

FSA: Plenty of our gearing is developed particularly for racing. Within the Tour de France the common pace is usually round 25 MPH, together with all of the loopy elevation they acquire. Professional cyclists don’t bat an eye fixed using over 40 MPH. Our professional bicycle owner Lachlan Morton topped 75 MPH throughout his latest Everesting file.

lachlan morton eversting road riding record set fsa pro athlete

The excellent news is that we provide tons of gearing choices to permit each rider have enjoyable and be protected using inside their very own limits. We additionally supply along with Compact (50/34) and Professional Compact (52/36) our Tremendous Compact 2x cranksets in 46/30 and 48/32 that may supply a decrease ratio for both gravel or highway bikes.

How does crank size relate to tire measurement? When mounting giant quantity tires the whole wheel circumference will increase. For instance, going from 23mm tires to 32mm tires will increase the wheel diameter by about 20mm. So, when touring at a given pace, the rear wheel makes fewer revolutions with bigger tires. Is it helpful to lower the crank size to compensate for bigger tires?

FSA: That’s an attention-grabbing query that may, little question, require an attention-grabbing reply. For certain, totally different tire diameters affect pace, cadence, and even energy vs rotation, however wouldn’t it require a unique measurement crank arm?

fsa 175mm crank set
Enduro World #three Kevin Miquel runs the FSA SL-Okay crank set with 175mm arms on his Sunn enduro bike – he’s 189cm tall

Usually, totally different crank arm lengths are useful to adapt to our personal particular person anatomy (leg/lever size), occasion (monitor vs TT), or using type/sort resembling spinners (sprinters?) and grinders who just like the leverage of pushing greater gears.

It may very well be a mixture of all these elements that steer us in direction of a sure crank arm size. A tire width (top) will have an effect, however not sufficient to benefit altering a crank arm size. Until you’re transferring out of your highway/gravel bike to an MTB; these bikes have such totally different tire heights and naturally the terrain could be very totally different too (assume crank arm clearance).

Is it right to say {that a} 10-50T cassette provides a 500% gear vary? The vary is from 10 to 50 enamel; thus, the vary share improve is (50-10)/10 *100% = 400%. Exemplifying: should you go from 10 to 20 the rise is 100%, not 200%; from 10 to 30 the rise is 200% and so forth. From 10 to 50 the vary % improve is 400%.

FSA: I feel each percentages are technically right, saying one calculation is healthier could be a distinction of semantics. There’s a 400% improve, however there isn’t any doubt {that a} 50 tooth is 5 instances greater than a 10 tooth. Most manufactures use the bigger 500% quantity, so for readability that’s most likely at the moment essentially the most helpful communication methodology.

Will there be a 44/28 ring mixture popping out? That may be my supreme gearing for climbing/bikepacking whereas preserving the jumps within the small cassette.

FSA: With the ever altering and evolving gravel class, we may see decrease chainring combos adapt to quite a lot of wants. Assume bike packing with the extra weight and wish to present riders that decrease vary to recover from climbs. Additionally, entry degree riders who merely wish to make climbs simpler, or anybody in want of that vary.

Any likelihood you’ll have brief crank set choices (150mm-160mm arms) for us shorties, or people who need extra boulder clearance?

FSA: We do supply our Gossamer Professional crankset in shorter ranges beginning at 145mm and going as much as 160mm in increments of 5mm. This covers most riders searching for out cranks to suit the smaller rider and the bikes that they experience. Keep tuned for up to date lengths all through our line.

Why is 46/30 (with choices to go smaller) not the usual 2x gearing for leisure gravel/journey bikes? We aren’t all 25 y/o and chasing podiums or Strava KOMs.

FSA: We’re discovering that with gravel and journey riders all in search of totally different experiences, the chainring choices are starting to reflect these riders. Whether or not that could be a beginner leisure rider attempting their first drop bar off-road using expertise; who would select a a lot smaller Tremendous Compact system, or the previous highway racer seeking to increase their very own horizons; who may need the ability of a bigger 2x, resembling 48×32 and even greater. Strava KOM looking is non-compulsory.

bwr cc gravel riding desert cattle grids fsa groupset

Why don’t the producers supply a variety of chainrings and cassettes so you may choose your personal ratios? That may be the most suitable choice.

FSA: That’s an incredible query and the short reply is that FSA does supply a large number of chainrings and might be constructed up upon request typically. Rings are additionally designed to work collectively. Ramps and pins, in addition to spacing from the massive to the small ring is optimized in order that shifting is easy and exact.

This works for each shifting to the massive ring and for coming off the large ring right down to small.  While you begin mixing ring sizes there’s a noticeable degradation in shifting efficiency as a result of issues should not lined up accurately and both dropped or wedged chains can occur, in addition to normal poor shifting efficiency.

After all, there are limitations with BCDs and body allowances, however riders can customise their drivetrains simpler now than ever earlier than. As for brand new bikes, despite the fact that the producers supply just one alternative usually, your LBS can assist out in making these modifications on a brand new bike buy.

What are you able to do with body that has a braze on entrance derailleur tab that doesn’t go low sufficient for 46/30 or 44/28 chain rings? Do you’ve gotten an adapter to decrease the entrance derailleur?

FSA: We do supply an adapter that may assist you to use a smaller entrance ring combo resembling Tremendous Compact. This easy gadget works on any entrance derailleur hanger, mounted or clamp-on type, to make it a straightforward method to decide on what chainring combo you want.

I’ve been using for almost 30 years and would think about myself delicate to modifications in crank arm size. I favor 172.5mm on the highway for stability of leverage and acceleration and 175mm on my commuter for the marginally decrease cadence I’ve when standing on the pedals uphill whereas overburdened with groceries, and so forth. I can see the enchantment of smaller rings, however how may I profit from shorter cranks on a highway bicycle?

FSA: Crank arm size might be helpful for quite a lot of causes, a very powerful is a rider’s personal lever arm size (leg size). After all, there are a number of different elements resembling occasion specifics (assume monitor, Tri, MTB), however for leisure riders who would not have a aggressive want for a particular crank size, there are easy formulation, resembling leg size x 5.48.

For instance, triathletes use very brief crank arms in order that their muscular tissues are prepared for the transition to the run leg. Highway riders who, such as you, benefit from the stability of spinning and a few leverage, stick with what works. And if you’re a triathlete or require a shorter crank arm size attributable to your private leg size, shorten it up.

Why not supply smaller rings than 46×30 (which isn’t IMHO actually small), particularly when these would match on the prevailing BCDs on some FSA cranks? 44×28 or 42×28 needs to be simple to implement with 90mm BCD, however these mixtures don’t exist. The modular cranks may match any measurement rings, like say 42×26, 38×24, and so forth. Not everyone seems to be a racer or has dropped carbon stays(!), and people bikepacking may usefully use as low a gear as they may get.

FSA: Agreed! That is among the large advantages of a modular chainring system; no BCD to restrict chainrings. For certain, if you improve the burden of the bike, decrease gears make it simpler for bikepacking and getting from level A to B.


FSA does supply each a 1x and 2x system to accommodate a rider’s wants, though with the evolution of bikepacking I can see FSA providing decrease ranges. Present 2x highway entrance derailleurs are optimized with work with bigger chainring sizes.

Lowering the outer chainring measurement an excessive amount of can have a damaging impact on shifting efficiency. Smaller chainrings would require derailleur cages which can be extra just like MTB entrance derailleurs.

How are you going to calculate for cyclocross racing and a 1x setup the place the candy spot is with crank size, chainring combo? I’m working a 36-9 13 spd cassette with 170mm x 40T up entrance. I would like burst energy for steep brief climbs, fast acceleration out of corners, and a excessive high pace for path sections. Cadence round 80 to 90 RPM is good.

FSA: Altering your crank arm size received’t have an effect on your pace at a given RPM. Altering your crank arm size will solely change the pedal drive you might want to apply. One strategy to examine crank arm lengths, gearing modifications, and wheel and tire sizes is with gear inches.  Sheldon Brown has a helpful gear inch calculator.

Which cranks can be found in sub 165mm sizes? Are these accessible as 1x or can they be transformed to 1x?

FSA: We do supply cranks right down to 145mm in our Gossamer Professional sequence, though keep tuned for availability.

FSA Gossamer Pro alloy road cranks get super short & sub-compact, 2x road compact

I would love an all-road bike for asphalt and gravel using. Would a 1x drivetrain setup be OK for my on a regular basis bike?

FSA: After all, 1x introduces a degree of simplicity and ease of use. Though it’s not an answer for all, it stays the default system for many, if not all, present MTB bikes the place terrain is tremendous diversified.

The place you’ll wish to think about a 2x system is for bikes (assume drop bar primarily) the place gear vary jumps are a lot nearer collectively. That offers the rider a cadence that’s smoother from one gear to the following. That is very true on highway and gravel.

Riders not wanting large jumps in gears and in the end, a rider who favors these extra refined modifications will gravitate in direction of a 2x system. Roadies tend to additionally favor this technique for a similar cause; a better gear vary.

I’ve all the time been within the mind set that 1x vs 2x could be very subjective to the rider sort, the terrain they experience, and background of the rider’s expertise. The excellent news is that FSA does supply a variety of 2x cranksets together with 1x that may work nice together with your alternative of arrange.

Why is the left arm pedal nut meeting on my FSA SLK Mild crankcase unfastened? Why haven’t FSA replied to my emails on this matter?

FSA: Sorry to listen to that. Recommend reaching out on to our USA tech and repair team- [email protected] They might be completely happy to assist with any points you might be experiencing.

Thanks very a lot to John McKone and the FSA Highway crew for answering all of the Bikerumor Readers’ questions!

Bought a query of your personal? Click on right here to make use of the AASQ type to submit questions on any cycling-related subject of your alternative, and we’ll get the specialists to reply them for you!



Please enter your comment!
Please enter your name here