Rebuilding MTB for commuting

I’m sure there are some experienced mechanics here that can potentially help me with this. In any case, I’m very grateful for all input, so that I can decide whether to go with the rebuild or not :slight_smile:

Since my really old commute bike is about to give up, I was wondering if it makes sense to rebuild my old MTB for inner-city use. The alloy frame fits me perfectly and it generally is in good condition. There are two things though, that I would like to rebuild. Replacing the suspension fork with a stiff (and much lighter) one and the Shimano XT 3x9 to a 1x9.

Now, I have never replaced a front chainring (or scrapped the front derailleur entirely, as I would do here). And neither have I ever replaced a fork. So I’m wondering if that idea makes any sense in the first place.
And if it does make sense, what could be potential stumbling blocks or obstacles that I would have to pay attention to?


PS: I know I could just leave on the 3x9, but if I go with the MTB, I’d like to use this little ‘project’ to improve my (very limited) mechanic-skills :innocent:

Converting to a 1x is easy enough. You’ll need a suitable narrow/wide chain ring with the correct bolt spacing (BCD) for the crank and number of teeth that you’d like (somewhere in the 30-36 range, probably). If you can find the model number of the crank, you’ll be able to get the BCD. Look on the back of a crank arm. You may be able to do the swap without removing the crank (slide the old rings over the crank arm for removal). You can get a fancy n/w ring like a Wolftooth for $80 or you can get a Deckas etc. on eBay for about $20. I have both, and they’re functionally identical. Both are great and last a long time. Then just remove the shifter, cable, and front derailleur. No tensioner or chain keeper needed with a narrow/wide. Depending on what size chainring you go with, you may have to shorten the chain, but probably not.

When it comes to the fork, that’s a little more involved, but not horrible. The brake swap is pretty straightforward regardless of type. If you’re interested in keeping the geometry of the bike the same, find the axle-to-crown measurement of your current fork and match that on the rigid. That’s not strictly necessary though, as it doesn’t make that much of a difference on a bike like this. The slightly more involved thing you’ll need to do is swap the fork crown race (where the lower headset bearing sits) from the suspension fork to the rigid fork. You can DIY it with a flat blade screwdriver, a mallet, patience, and an appropriately sized PVC pipe (for installation on the new fork), but that might be best left to a shop if you’re not comfortable. On that note, make sure you get the correct diameter steerer… either tapered or straight 1 1/8". If it’s old, it’s probably the latter. Or you can leave the fork as-is, because on a commuter, it doesn’t make a lot of difference, nor does any weight savings. All the better if it has a lockout.

As somebody who likes to ride MTBs on pavement, the biggest gains/ease of riding will come from tires. Get a fast-rolling tire with small knobs like a Specialized Renegade or Gravelking, or if you’re feeling saucy, try slicks.

Since this is the internet, I’m sure you’ll get conflicting advice and I’m probably 110% wrong. Treat the above as a general how-to.


I’ve got a 32 on my MTB and it’s as good as the blackspire it replaced. Plus stupid cheap if you’re not sure what size you’ll want for commuting.

Fork wise I think I’d lean towards a shop fitting after poorly trimming a steerer tube back in my uni days. If you’ve got a buddy with cutting guide then it’s not a difficult job. Just needs correct tools.

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@Otis.Watchjack Wow, that’s a really really helpful post. Thank you very much!!! :clap:

Thanks also to @cromulent_munki for the input.

I have done the same to several MTBs, three of which I sold, one I kept. “Cityfying” an MTB, to me, means swapping out the suspension fork for a carbon replacement, replacing the existing stem and handlebar set up with an integrated carbon bar, putting on lighter, skinnier, slicker tires, and leaving it at that. I wouldn’t waste the money converting the crankset from a 3x9 to a 1x9–you will still have the range that you originally had, and you won’t have to spend a chunk of money to essentially do the same thing–yes, 1x9 is popular now, but I would only do that if I were building a bike from the ground up.

On an existing old school MTB, I’d keep things to a minimum. Here’s my converted Giant MCM with carbon integrated handlebar, carbon non-suspension fork, lighter tires (1.25 Maxxis Detonators in the picts, sometimes I go even skinnier with 1" Ritchey Tom Slicks)–since the frame is carbon, the whole set up weighs less than 20#s–pretty good for an MTB–for me, the perfect commuter.

While both the frame and forks are set up for disc brakes, I have resisted, and I do have to say it is a challenge to find a 26" carbon fork which allow for canti brakes, but, as shown, it can can be done. I would see no advantage using a 1x9 crankset for city riding compared to the changeover costs (essentially all new mechanicals).

Thanks for the comment and the pic. Nice bike … kind of where I’d like to end up (except for the carbon frame).

The 1x9 is definitely not a neccessity, but much more me wanting to get some experience :slight_smile: I’ll reconsider it though. Maybe go step-by-step and do the fork first :thinking:

Starting with the fork would make sense. If you put in a 1x9, besides the new crankset, you’ll of course need a new rear cassette, new rear derailleur, and a new shifter/brake set up–a fairly costly undertaking, which won’t have any real impact on the quality of your ride in the city…

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He won’t need any of those things. He’ll be commuting with it, not riding trails. His existing mtb cassette will have plenty of range with the right size chainring, and a standard RD will do a perfectly good job of keeping his chain on while he’s riding on asphalt. He could probably go quite well just using one of his existing chainrings in the middle position of his crankset, and only actually spring for the narrow-wide if he finds he has trouble with losing his chain.

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Uh, yeah, and that is exactly what I clearly said–in case you missed it, here it is again “I wouldn’t waste the money converting the crankset from a 3x9 to a 1x9”–keep the original set up the way it is–and change the fork first. He’s the one that suggested switching the triple for the single, which I countered by saying that that approach would be costly, and essentially buy no new advantages.

I think you missed what I’m saying.

He could take off his FD, left shifter, and 2 of his chainrings and run his bike as a 1x commuter, without adding/replacing any parts. His bike would be (slightly) lighter and simpler to ride. A 1x conversion only needs to be expensive if it’s being put to the test.

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You don’t need any of that stuff. A clutch rear derailleur is only necessary with the sometimes pointlessly huge range cassettes that are all the rage these days. They don’t to a ton except suppress some noise over really rough terrain on something with an older 9/10/11 speed cassette. Half the time I forget and have the clutch turned ‘off’ on my 11-36 and 11-34 1x MTBs, and nothing bad comes of it aside from a little more chain slap and a little better shift quality. Shifter/brake/cassette stays the same as well, but I would suggest that cheap narrow/wide ring. Dropping chains sucks. You can do it with a normal ring, and yeah, that might be worth a shot to see if you like it before going any deeper.

Anyway, good call to the other reply about steerer trimming. Forgot about that part, but if you look around for a used fork with steerer that’s close to what you’re taking off, that can be avoided. The act of trimming a steel steerer is easy, but as always, tools like a cutting guide ($15) and a hacksaw with the appropriate blade are helpful.

All advice here is pretty sound. Having done this more tines than I can count, here are my tidbits.

  1. fork - you don’t have to buy a 26" fork and in reality I’d look for one for a 27.5 or 29 as this will correct the height for your suspension. Your frame is built around a fork with a tall axel to crown, which you need to match. Get the shop to install it. Between cutting the steerer, installing the star nut and crown race, you need three specialized tools without which you will do a piss poor job.

  2. 1x9 - totally reasonable to lose 2 of your chainrings. Are you thinking of a new chainring in a size between your middle and big? Or just leaving the big one on? Either way, you will need to buy special chainring bolts that are shorter. Your existing chainring bolts are designed to clamp 2 rings and will not tighten down properly if only one ring is there. Put it in the spot where your middle chainring was, this will give the best chainline. You definitely don’t need to invest in any new drivetrain bits or even shorten your chain if you are keeping your cassette and chainring. As mentioned, unless your commute has rock gardens, narrow wide, clutch derailleur etc are unnecessary.

  3. wheels - if you really want to go crazy, rebuild your wheels with 27.5 or 29 rims. You can fit 29x27cc in most 26" mtb frames. You could probably fit 27.5x42. That would be awesome!


^ I had a 700x35 setup on an old 26" MTB frame. It worked fine, and BMX offset brake mounts allowed me to use rim brakes. It was… interesting. Not worth the effort, really. Ha. I found fast-rolling MTB tires to be both more comfy and more fun. You can still run over big bumpy things and not worry really about it. The speed differential between a fast rolling MTB tire and a 35mm road tire on a flat bar pavement ride isn’t that great, and the 1 mph or so at a cruise is pretty irrelevant in a commuter.

While a fun experiment, I’d not recommend it.

Wow, that is so much more info than I was expecting. Thank you very much to all of you. Your input is highly appreciated!

I’ll post a pic once the rebuild is done (or underway). Might be a while, but I promise to post something here.

Thanks to all and have a nice weekend!

A bit late to the party but if you want to take the small chainring off you’ll need to pull the crank. The correct tool (or if you’re lucky just an 8mm hex key) for that will depend on your BB/crank combination.

Which brings me to the question what tools you have to do this work? I would highly recommend investing around $200 for a basic bike tool kit. Plenty of options out there and you’ll be able to do other maintenance such as swapping chains, etc. Every job is easy with the correct tools. If you search CT for Dave Rome’s tool kit article it’ll give you a pretty good idea what’s out there and at what cost.

I would keep the 3x9 drivetrain for a commuter as I see no advantage to having less range on a utilitarian bike. I also have an MTB to Commuter conversion and at times, I want that granny when I’m going up a hill with 15 lbs of groceries in my rear panniers.

I’d also put a rigid fork on there. Additionally, I’d rebuild the front wheel with a dynamo hub and fix permanant lights front and rear. It’s so nice to just pickup and go when it’s dark out without having to wonder if you’ve charged your lights.

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@Mad_Black I do have some tools from regular work on my road bike. As for a toolkit - I rather buy single tools whenever one becomes neccessary. Toolkits always have tools that I either already have or won’t need. Either way, that’s definitely no problem for my “rebuild”, the Hollowtec key is available :slight_smile:

@Jay_Tee I don’t have any uphill parts on my commutes and therefore haven’t used the mid or small ring ever since I started commuting about 2 years ago. However, that part has been delayed for a bit.
As for the dynamo hub - I have thought of adding a dynamo and am well aware of the advantages. However, I dislike the look of it so much, that I rather go dark than install a dynamo :see_no_evil:

The parts have been ordered and might arrive in the next few days. So stay tuned, if I don’t mess up, the pictures will be coming shortly :grinning:

Non-tech angle. You want to have nicer bits so it’ll be fun to ride. But not so nice that it becomes a target or should it be stolen. Difficult to ‘optimize’ a beater.

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I’m still jealous of my wife’s beer bike, although she doesn’t know it’s a beer bike, she thinks the basket is for groceries;)
She has hydraulic rim brakes, a carbon bar and titanium rail saddle!
I found the bike abandoned. Repacked all the bearings and upgraded from our parts bin.

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It’s done! :partying_face:

The switch went pretty straight forward, except for the crown race. Removal from the old fork was no problem, but getting it onto the new one, without any special crown fitting tools, was a nightmare. Lacking proper equipment, it had to be a hammer and chanel-lock pliers. Worked ok-ish, but I couldn’t get it down the last millimeter.

Enough talk though, here’s the pic

A 1k testride was ok (although it felt a bit strange :slight_smile: ).

With this first step accomplished, I’m afraid it’s on to step 2 - the Gravel-conversion! I’ll do some reading and info collection and when I think I’m ready to seriously consider the conversion, I’ll start a new thread … presumably with a ton of question :see_no_evil:

For now I would like to thank all in this thread for your help and guidance. Don’t think I (c)would have done it without you!

@RAHrider A beerbike! How awesome is that :joy: Although I have to admit that I’m glad you didn’t post this a week earlier. I certainly would have gone for the beer-conversion instead of fork and gravel :rofl: :rofl: :rofl:

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