dvai

Hi everyone.
We got a Specialized Sirrus 6. Came with a 2x11 105 group set with a Praxis crankshaft.
My wife would prefer a single speed front derailleur and just deal with the rear gears.
The crankset is 46/32t. The rear cassette is I think 11-32

How easy is to switch to a single speed? Is there a way of just switching the chainring or I need to switch the crankset?

Finally, what size would be a good "middle of the ground"? 42t?

Attached pics of the current one and where we want to get.

prj71

Does your shop have a Sirrus X? They come 1x already. Maybe they would let you trade in.

big john

A single speed front derailleur? Sorry, couldn't resist. The simple thing would be to just not shift the front. I don't see what you gain by going to single ring. Is this for flat rides only? If you are climbing with a single ring you probably have to change the cassette and maybe the rear derailleur.

Digger Goreman

Search my threads and find my recent foray into going 1x. Also a lot of vids on YouTube. The short answer is that it is probably NOT worth the time and effort. HOWEVER, there are advantages, vis-a-vis tradeoffs.

Your overall range is greater with a 2x or 3x, at the cost of some weight and "complexity" of shifting a front derailleur. The range issue CAN be (sometimes) partially to fully solved by throwing money at it (in varying combinations: new chainring, cranks, wide range cassette, maybe bottom bracket, and maybe chain, and probably a "goat/road link"... as well as any labor costs) going 1x.

I would suggest a period of experimentation with what you have. What ratios (front gear tooth count/rear tooth count) propel you up and down hills the way you like? IF you give up something in a compromise to 1x, which is more important: climbing/downhill speed?

You are modding a 2x. The chainlines are compromises around the non-existent middle ring. A 1x (optimally) should have a straight, middle chainline, necessitating a change in bottom bracket to achieve it.

Chainring should be a wide/narrow tooth to prevent most chain losses. If not ridden off road, may not be absolutely needed. Alternately, or in combination, a chain retention guide may be useful. If changing to a wider range cassette (above 9 speeds?) a different size (width) chain may be needed.

What to put in front and back (tooth count) is a dynamic. If you go with trying to achieve the same range (as I did) then there will almost certainly be bigger "skips" (and therefore, possibly unacceptable effort changes) between shifts. Cadence seems to be more valued by road cyclists, more or less by commuters, and less by mountain riders. For me, my triple ratios (22/32/42)(11-34) were 3.99 to 0.81. I chose a 40 tooth front and 11-50 rear (mountain bike, I'm not sure road bikes are rear spaced enough) for 3.6 to 0.8 ratios. Good enough on the downhills and fine on the climb (I'm almost exclusively a commuter).

The more you experiment and plan, the better will be your experience (and you may abandon the project, saving LOTS of time and money). For me, I enjoy the simpler aesthetics, including not fidgeting with, or worrying about, the left/front shifts. With my rolling hills, and commuter mind, switching cadence was not a hassle. In the end I DID have to change out the whole drive train (except rear derailleur) and spent just short of a "C-note" in labor that I couldn't do. No regrets....

dvai

Thank you all for the reply. I really appreciate it. (and yes... 1X front derailleur...lol).
RE the Sirrus X. We originally going to buy a Sirrus X, but was backordered. We should have waited. Now is too late unless I trade in and lose money.

Her issue is that the chain rubs when the front derailleur is trimmed. She manages using just the big ring on the front derailleur but is the trimming that is a pain. I guess we could wait and see if she gets used to it but I though there is a relatively easy way of just going 1X. Also, derailleurs require maintenance and adjustments. So simpler is better. She doesn't need a wide range of gears as long as she can use the 11 gears in the rear with no rubbing.

I know I could just go to a LBS and ask- but Im sure they are happy to sell me new chainrings and charge for service so I trust you a lot more
:-)

I emailed Praxis and see if they have any input.

BTW, I got a new bike with e-shifting last year and was the best thing ever- The trimming system in mechanical sets can be a pain. I hope that eventually these electronic systems come as an option in hybrids and more affordable bikes.

Iride01 

Just put it in the big ring or the small front ring and leave it there. Then she'll have the option to use the other chain ring only when needed.

Don't worry about the chain rubbing. You can replace the chain and anything else that might wear more inexpensively than you will change this bike to a proper 1x with the correct range of gearing needed for the terrain she rides.

msu2001la

I swapped a 105 2x setup for a 1x setup on an older CX bike and it was pretty simple. I used the stock crank and just bolted on a narrow wide 1x chainring. It ran fine with the 105 rear derailleur, but I was able to pick up some SRAM Force 1x shifters and RD on the cheap, so I switched out to those as I wanted a clutched RD for CX racing.

I don't know the specifics of that Praxis crank, but you would just need to find a chainring that fits the BCD (bolt circle diameter). You also might need different chain ring bolts, as I found on mine the 2x bolts were too long for a single ring - I was able to buy shorter bolts on Amazon. (EDIT: Looking at the photos it looks like your big and small rings might attach differently than on my crank, so you'd probably need to do some research on what is needed to run a single ring on that crank. The second photo you posted shows a direct-mount chainring which is different than the 4 bolt model you have)

I've never had any issues with chainline, but the end result is that the front ring (42t) sits basically in the middle of my rear cassette (11-32). I also find this gearing to be just fine for casual flat-land road riding. It's a bit low for faster group rides and would also be unsuitable for longer alpine climbs.

tFUnK

Chain rubbing against the FD cage is super annoying. Usually if you want to go 2x to 1x you can just replace chainrings, but I'm not sure if the 1x chainring pictured will work with your current crank (it may be that you can take the whole spider off and just put on the new chainring).

big john

If rubbing is the only issue you could just take the front derailleur off. It may just be she needs a little more time to get familiar with it. It's not rocket surgery, after all.

I'm not super diligent with maintenance but the front derailleur almost never needs attention.

If inexpensive bikes came with electronic shifting they wouldn't be inexpensive bikes anymore.

I have a triple on one road bike and a double on the other. I have a 1 by on my mtb. It's fine on the mtb because I don't need a wide range, just low climbing gears.

Troul 

Remove the front Der & put a chain saver high up then positioned out to prevent it from dropping to the 32t.

Polaris OBark

If it were me, I would leave it alone and suggest she just keep it in the smaller cog in the front.

I live very near Alba Rd, which the crankset is named after. With a 32T large cog in the rear, and the 32T chainring of the Alba crank, I would struggle to ride up Alba without standing for 4 miles.

bboy314

You could replace the chainring, cassette, rear derailleur and chain, copying the Sirrus X’s gearing. Using your current drivetrain with a 42 tooth chainring would significantly limit your low gear range. I think praxis offers a direct mount 1x chainring for that crankset.

Add up the cost of all this and the trade in option might look more appealing.

xroadcharlie

That is an expensive bike. I don't understand why the front derailleur is rubbing. It shouldn't be. It just needs some careful adjustments. Try adjusting the limit screws when it is rubbing for a little clearance. Even a cheap Shimano Altus front derailleur used on many entry level bikes doesn't rub.

I do prefer a single chaining for the clean looks. But the bikes I looked at don't have proper spacing. So mine has a triple chainring. I didn't think to just ask the dealer to put a cassette on the 1x model with better spacing.

sdmc530

praxis makes narrow wide chain rings for that crank and its an easy swap out. but you might want to put on a chain catcher because the rear mech has no clutch. You wouldn't have to put a catcher on but never hurts either. A narrow wide would be a must though.

I just built up a 1x for my sons first road bike but only a 9 speed cuz that what parts I had on hand. I would do a 2x over a 1x but he is thrilled just to have a drop bar bike.

I do have to agree though, I wouldn't change it being its a full 105 with praxis cranks. I would just leave it as is and ask her not to shift if she doesn't want to. But if your dead set call praxis and order a narrow wide.

You won't know what gear she will like the most so you will have to guess on front ring size, I would start at 46 if it were me.
GOOD LUCK

Dean V

You need to take notice of what gear range suits your wifes requirements. Observe what gears she wouldn't miss when riding the 2x setup and then translate that to what she would need with 1x.
No one else can tell you this as it is dependant on terrain, fitness, weight, cadence preference etc.

prj71

Front derailleur can be adjusted so that you have no rubbing.

msu2001la

Eh. I get that this is the road forum and we're all normally sprinting off the front at 35mph+ and what not, but 46T with an 11-32 on a flat bar hybrid is pretty tall gearing.

I'd probably start with a 40T, which would be good for 28-30mph top speed and still give some kind of reasonably low climbing gear for small hills.

prj71

I'm betting the 1x Crank on the Sirrus X would be a direct fit on the Sirrus 6 without any problems.

msu2001la

Yes, but the OP doesn't need a new crank. Also, it looks like the Sirrus X actually uses the same crank (Praxis Alba)?

Unless I'm missing something, The Praxis Alba M30 crank that comes on that bike is a direct-mount design. On the OP's bike, it comes with a 2x direct mount spider, but can also fit a 1x direct-mount chainring (which is what looks to be included on the X model). The only caveat here is that Praxis says 1x setups must have a clutched RD and they recommend a chain guide. The Sirrus X uses a 12sp Shimano SLX RD that is clutched. I'm guessing the OP would be fine with the 11sp 105 RD (not clutched), but I'd definitely run a chain guide with this setup and know that chain drops might happen sometimes.

Here's a bunch of info:

Praxis Alba website: https://praxiscycles.com/product/alba/
Direct-mount 1x Chainrings: https://praxiscycles.com/product/dm-...oad-wave-tech/
Here's the instruction manual: https://praxiscycles.com/wp-content/...-DIGI-REVH.pdf

The OP is gonna need a torque wrench.

Digger Goreman

YHMV (Your hills may/must vary) from the ones I climb in the subdivisions of north Stone Mountain, as I need 0.8 ratio for short uphill distances to make it (5-6 mph). Ofc I'm pushing 61 years, but have no medical problems and able to do the 6.5 mile trip at 12-13 mph (for comparison purposes, if useful). Combination of street and mup travel, with a little off road.

One of the bennies, I feel, of going 1x is the ability to economically change the chain ring. If I do start losing my abilities to time, then I anticipate just reducing the front chainring to maintain climbing. For others, who might move or travel to other terrain, spare rings could make the new terrain more pleasant.

prj71

I don't think a chain guide is necessary. I have a 2019 Sirrus X with 1x and it doesn't have a chain guide. No problems at all.

rosefarts

If you can pedal backwards without autoshifting on the cassette, it typically means you’ve got a good chain line. No need for a guide in that case.

On my gravel I’m running 40x10-42 and on my last assignment ended up using it as a road bike. It’s close to perfect off pavement but was definitely noticeable when trying to spin. Maybe a 10-32 on very lightly rolling terrain, but after that, I’m in no hurry to get a 1x road bike.

If trim is the issue, would your wife be amenable to bar end shifters or Gevenalle, or downtube I suppose. They’re all a lot more intuitive to trimming.

Just let her practice, if my wife can do it, so can yours.

msu2001la

The Sirrus X has a clutched RD.
I don't use a chain guide on any of my 1x drivetrains either, but they all have clutched RD's. If I had a regular 105 RD, I'd run a chain guide.

msu2001la

Agree.
In the context of the OP's bike, a standard 105 rear derailleur is limited to 11-32. 1x is going to limit the range of gearing significantly and the OP will either have to decide if they want climbing (smaller front ring) or more top end (larger front ring). It's relatively easy to swap rings, but doing so for every ride is not practical.

The OP asked for "Middle of the ground" gearing options. 40T is pretty typical for 1x setups on bikes like this, but they usually come with larger range cassettes (and RD's that can handle them). Unless the OP wants a whole new drivetrain, they are going to be stuck with 11-32 as the max, so they will need to decide how low they can go on the front ring and still have enough climbing gear for the terrain they encounter.

xroadcharlie

That Specialized Sirrus 6 is a very nice bike with the 2x chainring. You made a wise choice, No need to 2nd guess yourself. Thanks to the proper spacing of the cogs on the cassette, You basically have 2 single chainring bikes in one. With the 46T chainring dipping to 39 gear inches on a very light bike, for many rides your wife may not need the small chainring, But there are times the wide range and low gears are very useful. One chainring will either space the gears too far apart, or have a limited range. The 2x offers the best of both worlds.

I'm sure many folks here on BF have 2x 10 and 11 speed bikes and don't have a problem with the front derailleur rubbing. You shouldn't either. This video shows you what's involved in correctly setting it up so it does not rub. You might want to try adjusting the limit screws first. If necessary have the dealer adjust it. If you bought the bike recently, they should do it free of charge.

Shimano 105 front derailleur adjustment screws - Google Search