bike wrench

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A place to ask bicycle repair questions, and for bike shop monkeys to share advanced non commercial wrenching resources (no YouTube self promotion). This is only for repair related topics.

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founded 1 year ago

I couldn't find almost any tutorials on how to disassemble or service this particular eBike motor (Bafang M400), so I just started removing screws and pulling out parts while taking a ton of pictures.

I found two dirty, rusty bearings that I cleaned and re-greased, along with all the gears, and then put it back together. Not only did I manage to avoid breaking it, but the noise seems to be gone as well. This was by far the most intimidating bike repair I've done so far. I've serviced every other part before, but I hadn't dared to touch the motor until now.

It also turns out that the motor is much better sealed than I expected, so I'll happily continue doing deep river crossings with the motor half submerged in the future, just as I have done until now.

submitted 4 days ago* (last edited 3 days ago) by evasync to c/bikewrench

I had no idea that cromoly tubes were so expensive so Im now looking for alternatives..

a generic question I have is, does it really matter on what I use of its not for a competition setup?

I mean I dnt care if its relatively heavy.. my initial thoughts was using stainless steel tubes or even construction rods but everyone online seem to recommend only using cromoly..

edit: ordered 5x25mm wtainless steel tubes for 15eur (1.5m) the same in cromoly couldnt find them under 70eur..

RJ lives! (
submitted 1 week ago by calamitycastle to c/bikewrench

NGL I assumed something had happened, and it kinda did, but this was an extremely welcome sight


So, I joined the world of waxed chains. So far, it's life changing. Quiet to the point that your think I'm running a belt drive, but more importantly, super clean and component preserving.

But, I was thinking earlier, if wax fills in the gaps between the parts the wear, how would you actually get a true chain wear measurement?

I've never heard of someone stripping the wax off to check for wear, and that would get incredibility wasteful to do it often.

Zero friction Cycling doesnt mention anything special in regards to checking a waxed chain.

So, would I go about checking the chain, waxed and all, and assume the numbers are pin point accurate?


I know some wobble is OK, but is this too much wobble on the rear axle? replaced the axle and the bearings, greased them up, screwed all into place. can't remember what it was before I replaced it, am I good here?


Just a rundown what is wrong on it:

  • totally destroyed drive train (cassette, chain, chainrings)
  • wheels aren't true/ lose spokes
  • rear derailleur is loose (I couldn't tighten some bolts) and has bad springs
  • bent V brakes (I don't know how he managed to do that)

If you want to know how the trip went look in to [email protected]

DIY true a wheel (self.bikewrench)
submitted 1 month ago* (last edited 1 month ago) by evasync to c/bikewrench

I had some wheel made but when they rotate they come in contact with the disc break pads (slightly).

The bikeshop that built them will take another month to look at this, as they are fully booked, and I dont want to pay 35+ on another bikeshop..

Is it doable to DIY this with a spoke key and using the fork as a stand?

(I think it would be a useful skill to learn as it will make me less dependent on bikeshops)


Basically title, this symbol is on the tires of my new (to me) CAAD12. Are the tires on backwards? The right side of the picture is the front of the bike, the left side is the rear. This is the front tire. Another picture below showing which way the tread is facing. The tread "looks" right, it appears it would channel water away from the center correctly.


Long story short: completely stripper the hex slot on the back of the freehub body while trying to remove it. It's incredibly tight. Can I just take a pipe wrench to it from the front or do the teeth seen here on the new part lock with the wheel hub making it impossible to turn?

submitted 1 month ago* (last edited 1 month ago) by evasync to c/bikewrench

Any brands that sell a rack like the one in the picture? (Edit: what i like from this rack is the mounting points on the frame that will result in a more comfortable ride than carrying the weight on the handlebars or fork))

If not do you recommend someone that can make this without breaking the bank? (I grew up in an agricultural area and there were a lot of folks that could weld something like that for a small fee - but some people online are charging 300+ for this, which is insane)

diy bike assembling (self.bikewrench)
submitted 1 month ago by evasync to c/bikewrench

Bike shops are asking 100+£ for a bike assemble and it might be justified but its too much for my budget and I want to DIY it.

Is that risky to do by watching youtube videos and borrowing tools from friends?

I want to install an english threaded bottom branket with a squared tappered crankset, disc brakes (mechanical), headset (threadless including cutting stem).


The photo was from a site that no longer seems to be up. The pedal on the right, measuring at 15.7mm is the same size that the pedal on my indoor spin bike uses and I want to use standard 9/16 threaded pedals instead.

Has anyone come across this size??? Do adapters exist to step up standard 9/16 to 15.7mm?


Fresh wheelset for my single speed and i noticed this out of the box. Should i be worried or is it fine?


Context: My 90s MTB still has its original Shimano chainring (crankarms say Alivo). The cassette was replaced several months ago, as was the chain and bottom bracket. No wear on the chain right now.

The derailleurs are Alivio, and probably the original ones from the mid-90s. I don't have any reason or intention to replace those, although, I do have a Deore LX on my decommissioned 90s MTB that I could likely drop in, but I digress. LOL

I guess two questions:

  1. What would I need to provide to my LBS as far as measurements to get me a replacement? I understand that I'll likely need another BB and maybe(?) a chain, but I plan to stick with the same gearing.
  2. Ideally, I'd want to find a 3x chainring where I can replace the crank arms and individual chain rings when needed. Will this be easy to find, considering the age and group set?

Thanks in advance.


Context: my ebike has 19mm nuts on the rear axle (and 15mm on the front). I have an old Proto wrench that's a 15mm/18mm, so i'm wondering if i could replace the rear nuts with 18mm nuts instead, so i can carry around one less wrench.

The bike is an Eahora Cupid with a 1000w motor if that makes any difference.


[I'm not allowed to post images because my account is too new, so those imgur links will have to do...]

While dragging my bike through some bushes, the exposed section of its rear brake cable running along the top tube got snagged in a branch and I ended up losing the small plastic piece that goes over the housing to turn the frame's cable guide (?) into a cable housing stop. I believe it's called a stepped ferrule or stepped housing end. Naturally, there is another such piece on the other end of the exposed cable, which I'm pretty sure is identical to the one I lost, so I can show you what it looked like:

My first question: What exactly is this called and where can I buy a replacement? Searching for "brake cable stepped ferrule", "brake cable stepped housing end", "brake cable stop" etc., I can find bits that look similar, but none that are an exact match.

My second question: Considering some bushes were enough to somehow dislodge or break one of these, I'm wondering how safe they are compared to alternatives like e.g. a fully housed brake cable or a different kind of ferrule (maybe made of metal):

That thin plastic step (see highlight in last pic of the album) has to withstand a lot of force and if it breaks the housing will just slide through the guide and the brake will fail.

The cable sliding out might also be a concern: I can see that rotating the ferrule gap to be opposite of the guide gap makes that unlikely and that even if they are aligned it's still unlikely due to the cable's tension opposing it, but I wonder if that's how I lost the other one.

Thanks in advance for any advice!

submitted 3 months ago by Leviathan to c/bikewrench

Hi all, I'm new to this community and this is me attempting to participate.

I've been repairing and building bikes for a good long while now. Mostly I bought parts off of Amazon or my local bike stores but I've run into a bit of an issue finding a bullhorn bar-end brake-lever/shifter combo for a 1x8 road bike. I can't find anything being made currently anywhere. I'm even starting to consider contacting some local machinists I know.

I guess this is the danger of endlessly customizing bikes to the point where you want to do stuff no one else has any interest in doing.

So let me know where you guys get parts and what your favorite procurement methods are for rare stuff.


Hello everyone.

I recently got myself a mountain bike from Canyon. It all works, got myself all the gear, pumps and all. And the pressure gage give me a reading of 10 PSI, which is odd because the tires are firm. 10 PSI should be nearly flat.

I have other pumps, including one that works for my car too, which I trust because I cross checked its values with my mechanic.

Here's the odd thing. I got the bike out and plugged it to the car tire pressure device and it also gave me a reading of 10 PSI. I also have a Topeak Shuttle Gage, 10 PSI.

How is that possible? I can't really believe all three readings come from faulty devices so I'm thinking I'm the one doing something especially stupid, or maybe a defect somewhere on the valve/tire but it's brand new, so I think I'm the one to blame. Any ideas where I've been an idiot?

I did open the nut on the presta valve prior to taking measurements.


(long time lurker, first time c/bikewrench poster)

I have a Bikonit MD750 ebike that currently wears its stock wheels with its third set of tires. The front is a 26" wheel (ETRTO 100-559) with 203mm brake rotors and 15x150mm thru-axle. The rear is also 26" (ETRTO 100-559) with 203mm brake rotors ans 12x197mm thru-axle. Both tires are 26x4.0, inflated to the max 30 PSI (~200 kPA), with a measured outside diameter of 74cm. On the rear is a 9-speed SRAM cassette and its matching HG-style splined freehub.

My problem: I use this ebike as a fast (40-45 kph, 25-28 MPH) inter-city cruiser on paved roads, rather than off-road as the manufacturer might have intended. The long stretches of road shoulder I ride on have all manner of debris, and the wide tires are constantly hitting things. In 1400 km (~860 miles), I've had four rear-wheel flats (with two in the span of 12 hours!), presumably from both sharp objects and pinch flats due to hitting protrusions at speed. These tires are also a drag, since under human power only, I can barely hold 20 kph (13 mph) but on my acoustic bike with 700x32 tires, I'm closer to 28-32 kph (17-20 mph). At higher speeds under electric power, this drag can only get worse. The original tires were Kenda Juggernauts (too loud on pavement), and the second set were Origin8 Supercells (too easily punctured above 32 kph (20 mph)). So I'd like to change to narrower tires, which also implies narrower rims.

Preliminary research: Since the weight of this ebike is around 40 kg (88 lbs), I know I cannot run narrow tires -- like the aformentioned 700x32 -- since it might concentrate the wheel forces on too little of contact area. Also, I want to keep the tire widths manageable when taking public transport: the buses and trains here have a tire width limit of ~2.5 inch (64 mm), and I will retain the stock wheels for mounting any tires wider than this. Two different references suggest that 23mm rims might be my sweet spot, giving me a range of possible tire widths to later purchase, from about 1.5" to 2.4".

For wheel diameter, I would prefer to retain or exceed the existing 74mm outside diameter, since it's not clear if I can easily reprogram this ebike's computer to acknowledge a different wheel circumference. A smaller outside diameter would cause the speed governor to engage prematurely, whereas a larger diameter is limited primarily by the frame around the rear wheel. By my measurements, this frame has clearance for an absolute maximum rear-wheel outside diameter of 82 cm. This reference indicates that a 29" wheel has a rough outside diameter of 29" (73.6mm), give or take. One size smaller is the 27.5" wheel, with a slightly smaller outside diameter of 27.5" (69.8mm).

Since my goal is to equate or exceed the existing 74cm outside diameter, I'm inclined toward a 29" wheelset. There may also be operational efficiencies, since a 29" wheel and my acoustic bike's 700C wheels have identical ETRTO diameters of 622mm. For example, I could possibly stock a single size of 700C spare tubes at home. Also, within mountain biking, there seems to be a trend of seasonally switching between fatbike wheels and 29" or 29"+ wheels, so I don't feel my desire is out-of-place.

Finally, I wish to leave the 9-speed shifter alone, so that I can swap between this new wheelset and the stock wheelset at-will. This means the new rear wheel must also be compatible with 9-speed HG-style cassettes. This compatibility chart indicates that if the new hub is Shimano 8/9/10 or SRAM 9/10 speed compatible, then I'm set. And if the new hub is Shimano 11/12 or SRAM 11 speed compatible, then I can use a 1.85mm spacer with my existing 9-speed HG cassette, which should be easy enough to find.

What I've found so far: With a search criteria for a 29" wheelset with 150mm front and 197mm rear, with a 23mm inner rim and HG-style splines, I've found very few results that aren't custom builds. The first (and least expensive) wheelset is from but it doesn't actually exist in stock, and its 29mm rim width is more than desired. The next from Biktrix is significantly wider, at 60mm rim width. The third and fourth are from Ican and Fyxation, at 50mm and 40mm respectively, and both wheelsets run into $700 territory.

Of those four, two use Novatec D201SB-15/D202SB hubs, one uses Fyxation's own hub, and one is unspecified. All appear to support 15x150mm thru-axle in the front and 12x197mm thru-axle in the rear. Other search efforts showed that a bit more variety exists if I went with a 27.5" wheelset, but I'm trying to keep to the criteria from earlier.

Hub variety: While researching 150/197mm hubs, it seems that various brands are relabeled, of varying quality. It seems Framed and Novatec are the same, Pub is made by Bitex, and DT Swiss is generally well-liked but expensive. I'm led to believe DT Swiss is on the higher end of the market, while Novatec and Pub are entry-level, with sporadic reports of years of life or months before failure. Certainly, on eBay, Pub and Framed sell for $40-60 while DT Swiss seems to be $300-400.

I need help: First of all, thank you for reading this far. What I would like is to know whether I'm so far off the mark that I need to start over, or if this is a mostly solid criteria and it's just that no ready-made wheelsets for my use-case are available and that I should build or commission my own wheelset. To guide toward an answer, I wrote out some questions:

  1. Are there alternatives I haven't considered for reducing punctures on an off-road style ebike currently wearing fatbike wheels?
  2. Is a 29" wheelset right for my bike?
  3. Is there some reason I shouldn't pair a 23mm rim width with 15x150mm/12x197mm hubs?
  4. With no experience building or specifying wheelsets, should I first build a cheap custom wheelset as a beta version, then later commission a "good for lifetime", YOLO, high-quality wheelset as the final goal? Or should I cut straight to the chase?
  5. Are there other -- ideally less than $1k -- wheelsets that I didn't find from my search efforts?
  6. Is 12x197mm thru-axle really that rare? Is it rare because I'm looking for such a narrow rim? Or because I'm making a grand tourer out of an off-roader?
  7. Is wheel-building difficult to do at home? Sheldon Brown makes it sound straighforward, although there was a post here earlier about computing spoke lengths.
  8. What 29" tires might be well-suited for speed, lower rolling resistance, reasonably high air pressure, and debris resistance on an ebike?

Any and all advice would be greatly appreciated. Thank you!

submitted 5 months ago by evasync to c/bikewrench

I have a steel frame and I'm looking on getting aluminum parts (eg: seatpost, headset etc)

Is Corrosion a concern?

Will I need to service the bike more frequently?

Is lube between the two metals going to make any difference?


I watched a video from Zero Friction Cycling where he tested a bunch of chain checker tools.

The original video can be found here.

Only a few were accurate, and the Park Tool CC-3.2 check that I've been using for a few years now, seems to be one of the bad ones.

Today, I decided to get the CC-4 (the Shimano checker they recommended isn't available in Canada, apparently), and rechecked the chains on my bike.

It went from "beyond 0.5mm wear" with the CC-3.2 to "not even close to 0.5mm" on the CC-4.

I guess I figured out why my chains weren't lasting long... according to the CC-3.2. 🤑😭

What chain checker tool(s) are you guys using, and have you used any that were just flat out wrong?

wheel hub question (self.bikewrench)
submitted 5 months ago* (last edited 5 months ago) by evasync to c/bikewrench

Im building a single speed mini velo with 20inch bmx wheels.

Right now Im at the process on building its wheels and I was thinking on getting bmx hubs instead of 'normal size bike wheel hubs' because they are cheaper.

Are there any downsides on doing that? Is there a substantial difference between these two types or it is just a marketing thing?


I want to build my own wheels.

What I got so far are the rims:

And some potential hubs: Rear: Front:

I would like to get some sapim spokes but all the online calculators online are failing me because I cant find all the data points they ask: is there an easy way to do that? Should I order the components first and measure them myself? (I felt that is kinda risky as I want to make sure everything would be compatible first)


So, I've got fresh Schwalbe Big Apple tires coming in for my Tern folding bike.

I hadn't realized it until I went to order, but the ones that came with the bike are last-gen Big Apple tires with K-Guard puncture protection and SBC compound. Now, I've never had a single problem with this version of the Big Apple tires. No flats in well over 4000km, and I take this bike on really long (150km+) rides.

The new version of the Big Apple tires are Raceguard with the Addix compound. This apparently makes the tires lighter, more durable, more puncture resistant, able to handle more weight, and have lower rolling resistance. It'll be quite the upgrade for the "same" tire.

I had originally ordered the set because my rear tire is looking pretty bald, and I'd like a fresh pair for this year. The front tire still looks like they have quite a bit of tread left on them.

Question: Should I replace both tires and get the all the benefits of the newer gen compound (keeping the old front as a spare), or will it not make enough difference to even worry about replacing the front tire right now?

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