Onza T-Pro build thread

[thousandwords]

DAY 9

 

On Wednesday the fork came. However, I had no spacers around, it was too late to go to a nearby bike shop (they were closed on Thu too) and was afraid to cut it at the minimum length (with no spacers) so it had to wait for a couple of days before going in.

Ordered from ebay a few bronze painted spacers that I think will blend with the frame. Should be here tomorrow.

[thousandwords]

DAY 10

 

On Fri the bike shop reopened so for a few bucks I bought 40mm worth of spacer stack (1x20mm, 1x10mm, 2x5mm) and played with stack height until I found a compromise between not looking too ridiculously high and allowing for enough height to further fine tune after I ride for a while and start having an idea on how tall the stack actually needs to be).

After a number of tries I settled for 3mm stack (actually 35mm- I don't like to install compression cap directly on the stem, so 5 mm are on top of the stem). Cut steerer and installed forks.

 

Also tried to complete the rear brake (all that was needed was connect the hose to the lever and bleed).

However, the Trialtech I ordered has an older type of fitting (as opposed to the newer, barb-olive-floating threaded nut, which installs like a breeze).

It inserts into the hose at one end and screws directly into the lever at the other.

I just have to say that once I started working on putting it together, I became disappointed it was designed around that older fitting, for a number of reasons.

1. being accustomed to the newer design, I appreciate some type on sealing "gasket around the interface fitting lever- basically that's what the olive in the new design does. It gives one extra confidence things won't leak when you squeeze lever hard.

2. newer system can be installed/removed with lever on the handlebar as the threaded nut is floating around the hose. The one that the lever came with needs the lever free to rotate around the fitting, as installing things by rotating the fitting instead will twist the hose.

3. the barb end of the fitting that goes into the hose is almost twice as thick as the newer barb, so it goes into the hose VERY hard, which is the biggest issue.

I tried to push the fitting into the hose numerous time, using various methods, none of which worked. I used a dedicated tool, specially designed to insert the newer barbs into hoses- the fitting needed so much force to go in that the hose was slipping into the tool!

Eventually, after a lot of frustration, I had to give up. It was Friday night and the bar and a buddy of mine were anxious to see me there...

 

 

PS. Off topic, but the bar restarted karaoke after 2 years of covid related pause.

I missed the fun of watching it every Friday night so much that I decided to actually sing although I had a feeling it might not go as planned.

Chose The Beatles' When I'm sixty four.

My worries were finally confirmed- I am not a gifted singer at all: I was dismal...I still had a lot of fun, and all the frustration with the brake fitting completely dissolved away (probably in the beer).

[thousandwords]

DAY 11

 

Saturday went up north hiking with a friend, which consumed the entire day.

But today, Sunday, gave the brake another try.

I had this idea- I wrapped one layer of sand paper around the hose, with the abrasive side facing the hose, the put the hose into the barb inserting tool. That did 2 things.

1. the hose got "fatter", so the tool gripped it better.

2 sand paper made it a lot harder for the hose to slip inside the tool.

It worked!

 

 

 

[thousandwords]

REAR BRAKE

 

Once fitting was in, I bled the brake.

I forgot to mention in an earlier post, but once fork was installed, I starting getting ready for bleeding, even before putting the brake together.

Identified caliper bleeding screw, removed it, and installed a hose with a Magura threaded fitting that I had from bleeding Magura brakes for my other bikes.

Big mistake as once screw was removed, I found out that the guy that sold me the caliper and hose actually left the original royal blood in there, and with both ends open now, it all poured out. Made me feel like an idiot.

So had to bleed from the scratch.

Syringe on the caliper end hose, receptacle on the lever side, push new royal blood in until lever hose starts filing. Swap roles, with syringe into lever hose, receptacle into caliper hose, push some royal blood in once pumping lever a couple of times. Take hoses out, install bleeding port screws.

 

Not sure this is the correct bleeding procedure, but I have to say- as much as I was disappointed with the Trailech lever design, it is one of the firmed hydraulic brakes I have bled, especially once you turn the reach knob a few turns out. It is solid.

Edited September 19, 2022 by thousandwords

[thousandwords]

FRONT BRAKE

 

I had an extra Magura MT2 caliper from one of my older bike builds collecting dust, so I installed it on the fork, getting ready to put the front brake together.

I even found to my surprise, the caliper fitting end of a Jagwire Quick Fit hose, the length was plenty, so installed it on the caliper and fork. Unfortunately I do not have a banjo screw, so I cannot finish the caliper end of the brake until I get one of those.

Needed a brake lever so I just ordered a Shimano Deore left lever off ebay for a decent price. I have everything needed for the lever end (barb, olive, threaded nut) so once lever gets here, front brake will be ready to assemble and bleed.

[thousandwords]

CHAIN

 

Forgot about it too- once chain got here in the package I received on Tue, I tried to install it, as rear wheel was in and so was the crank with the freewheel.

But ran into an issue. The Park Tool chain breaker I have has too small of a pocket for the chain I ordered...this is the first time this happened to me, I must have serviced 15 or more chains so far for all my road and mountain bikes with it and it has always fit.

Called Park Tool they confirmed that some chain manufacturers nowadays use wider chain plates which won't fit the older chain breakers they made, so they came up with a newer version of the tool- no more pocket, just a shelf the chain sits on, so that tool will fit virtually every chain no matter how wide.

Ordered that, should be here tomorrow. Once here, chain will go in and the snail cams will be put to work.

[thousandwords]

Due to hectic schedule did not take many pics along the building process for the entire week, but took final pictures of the bike as it stands to day with rear wheel on, rear brake fully functional, fork and handlebars on.

The pics with the fork on the star steps show a decent rendition of the geometry if the bike had a 24" wheel on (only 1" too high, axle is 13" off the ground as opposed to the correct 12")

[Mark W]

10 hours ago, thousandwords said:

Not sure this is the correct bleeding procedure, but I have to say- as much as I was disappointed with the Trailech lever design, it is one of the firmed hydraulic brakes I have bled, especially once you turn the reach knob a few turns out. It is solid.

It isn't especially - you only need to go from caliper up to the lever. You also shouldn't need to wind on the adjuster dial to firm things up. That would suggest there's still some air in there. With the Trialtech lever that should be relatively easy to solve though - rotate the lever so the bleed port is the highest point of the lever, wind the adjuster dial so it's completely 'off', open up the bleed port, attach the bleed hose, then fit a syringe without its plunger. Pour some fluid into the syringe, then give the lever a couple of quick pulls. Doing this in a way where you pull the lever in then flick your finger off the lever so it returns really quickly can help out with breaking up any air bubbles and getting them to move up the hose faster. If there's any air in the system it should rise up and into the hose/syringe. It's worth tapping along the hoses in case any air bubbles have stuck onto the inside of the hose walls. 

I've always called these top-up bleeds, they work really well as a kind of interim bleed or if you think there might be any air in the system. They're much quicker and easier to do than a full bleed, but should give effectively the same result.

Just on the barbed fitting vs. shroud and olive, I believe it was done to help minimise weight and lever size. Barbed fittings are M6 compared to M8 for the olive/shroud, so the lever design can be slimmed down. I believe the actual port itself is shorter than the port you need for a shroud & olive combo too, so that helps with getting things smaller and more out of the way too. There are pros and cons to each, but once you've got the bits you need to install a barbed fitting it's not too much hassle typically. If you've got an old spoke, wind a nipple onto the end of it and then cut the spoke a few cm down from the threads - you can slide the barbed fitting onto that bit of spoke and use the excess as a guide for the fitting into your hose, while you then tap the head of the nipple with a hammer/mallet. You'll still need some form of clamping blocks, but the spoke guide really helps out!

[thousandwords]

Thanks Mark, the trick with the cut spoke is awesome, will definitely use it next time I have to insert one of those fittings!

And my statement about the adjuster was a little misleading, it's not that it makes the brake firmer- in fact the lever travel stay the same. But by moving the lever away from the handlebars it just makes it easier to "modulate" applied force, especially harder force for firm braking (it could be just me, but if the lever gets a little close to the handlebar, it gives me a sense of too much force applied so I tend to back off).

I would say that the lever travel is about 1/4-1/3 of an inch from rest position to end of travel under decent pull.

There are probably still a few small air bubbles in, so I will in fact perform the top-up bleed you described.

 

[thousandwords]

DAY 12

 

CHAIN

 

New Park Tool chain breaker came so chain went in.

I have to say, those snail cams got turned all the way to the maximum radius in order to have a firm enough chain (from what I saw in videos of people gauging the tension by squeezing the chain- I will know for sure once I start riding and there is no chain slip).

 

Also, did something probably a little controversial for chain tensionig.

I have the snail cams on the inside face of the dropouts on both sides.

But given that the Trailtech rear hub I bought has a somehow unique design (10mm bolt on the drive side, acting bot as clamping bolt and axle), I could place a chain tug on the outside for extra secure axle lock in position.

On the non drive side the hub uses a typical (I think 6 mm) bolt that threads into the axle itself, so the chain tug 10mm hole is too large for that bolt and it would be free to move around if given a chance, so I did not bother with a chain tug on that side.

 

Finally, once chain was taut, I adjusted the slave cylinders to line up with the new rim position.

 

[thousandwords]

On a much lighter note, spacers bought online came, so they took the place of the placeholder spacers I had on in the interim.

Not super consequential, but I really like them

 

Once I ride for a little while I will have a better idea of the optimal stack height.

 

Edited September 20, 2022 by thousandwords

[Mark W]

10 hours ago, thousandwords said:

But given that the Trailtech rear hub I bought has a somehow unique design (10mm bolt on the drive side, acting bot as clamping bolt and axle), I could place a chain tug on the outside for extra secure axle lock in position.

On the non drive side the hub uses a typical (I think 6 mm) bolt that threads into the axle itself, so the chain tug 10mm hole is too large for that bolt and it would be free to move around if given a chance, so I did not bother with a chain tug on that side.

The M6 bolts in the 10mm hole isn't an issue - it's how the bikes came specced from Onza both in this form, and on their bikes like the Onza Zoot. While you're tightening the tug to adjust the chain tension, the chain tug is pulling the axle back while the chain tension itself is effectively pulling the axle forward, so when you tighten them the axle bolt will just sit at the 'front' end of the hole. The plate on the end of the dropouts will keep the tug itself stable while you're tightening it up, so it won't be able to tighten off axis or anything weird like that. With the axle bolts fully tightened up afterwards it can't go anywhere   Just make sure to use plenty of grease on the axle bolts and inside the axle to get the most possible torque through them.

The only other thing to note is that when you ride, the chain will stretch and you'll need to tighten the tugs/cams up to take up that slack. If your cams are towards the maximum end of their adjustment now, you may find that you'll either need to just use the tugs, or get some larger cams. I just had a quick look at the TartyBikes site and it seems that the Comas are towards the larger end, with only Hashtagg and Trialtech being larger. They only have 1mm more adjustment at the largest end though, so it won't be a huge amount. In all honesty, the snail cam bolt holes on those T-Pro frames were probably more afterthought rather than anything else. I'm fairly sure the bikes only ever came with chain tugs, and most riders used them like that, so it's possible that they didn't really check how the snail cam positioning would work in practice.

[thousandwords]

Another hectic week at work so again some catching up is in store.

 

DAY 13 (spread over three consecutive days in short spurts after work).

 

 

Front wheel stuff came from Tarty on Mon. Once home I jumped right into lacing it as I was anticipating the end of the build project and could not wait to get on the finished bike for the first time.

My excitement cost me though, as at first try the spokes seemed to short for a two cross and too long for a single cross.

Just to save some time I planned on ordering new spokes state side and briefly considered what crossing pattern to go for.

It was getting late though so called it a day at that point.

Next day after work I decided to give the spokes I received one more try- I took all outside spokes out and loosened the inside ones as much as I could- wheel laced together with ease on a two cross pattern. In my excitement the night before I threaded the nipples too much so shortened the inside spokes to the point where the outside spokes became too short. Oh well.

Once again getting late so left truing dishing etc for another day.

Third day (yesterday) finished rim (true, dish, round spoke tension, etc), rim tape, tube and tire on, then front tire went on the bike! Bike looks complete from a distance, but front brake still needed assembly and bleed.

[thousandwords]

DAY 14

 

This is again short episodes spread over a few days as I needed to wait for parts to come.

 

FRONT BRAKE

 

Last piece of the puzzle before bike was complete.

While previously working on other stuff (front wheel, etc) I looked around for miscellaneous parts I at one time bought for previous builds that I could use to put together a front disc brake. I was actually able to find most everything I needed.

 

For caliper I unfortunately had only 2 pot calipers (I wish I had a 4 pot laying around), both Magura- an MT and an MT4. Unfortunately the MT4 was missing the banjo bolt, but the initial plan was to get a bolt for it and use it, as it would be the slightly better caliper.

Also unfortunately- the banjo bolts for MT and MT4 are different- the MT4 needs a larger bolt.

To my surprise banjo bolts are a very hard to find commodity by itself. I suspect the main route they are acquired is with the caliper itself, but when it comes to buying them separately, the choices are incredibly sparse.

I started combing through the Jagwire wide selection of kits in hope one would have banjo bolts included. None did. Even called Jagwire- to no avail.

Next visited the local bike shop. In the past I always found everything I needed there. Not this time though.

Then moved to online retailers, etc. The only place I found something was ebay- one UK seller had some in stock; they were inexpensive so ordered the set.

I knew it will take a while to come so in the meantime I fell back on the MT caliper.

 

From previous builds I had leftover Jagwire Magura quick fit kit with fittings- banjo and seals/gaskets.

And to my surprise I even found one half of a Jagwire quick fit hydraulic hose. Red, which I thought would look out of place on this bike but I'll take it.

 

Put everything together, and the result can be seen in the last set of pictures posted after front wheel went in.

 

A day or two later I proceeded to bleed the brake.

To my dismay, it turned out that the Jagwire hydraulic hose was leaking at the interface with the banjo bolt.

Had to call it a day, ordered another Jagwire pro hydraulic hose (celeste this time, which would blend with fork well) and for good measure some royal blood and a back up Magura quick fit kit.

The hose and back up magura kit came in a few days, but did not want to put brake together yet in hope the banjo bolts will fit the MT4 caliper and I could use that one for the build.

 

 

In the meantime, while waiting for the banjo bolts, took the bike out and rode it around the driveway for a few days, 5-10 minutes each day.

For one, I could not wait to find out how bike felt, even though I had no functional front brake.

Secondly, while shopping around for the freewheel during the first phases of the build process, I noticed that Tarty recommends "breaking in" most freewheels by normal pedaling and freewheeling before any trials type riding. I think I remember them saying that without doing that you risk the pawls starting slipping. I think for the particular freewheel I got (Trialtech) no such warning was posted, but thought it might still be a good idea. Not that I would be able to do any trial specific riding anyways ha ha.

First thing I noticed was that the rear brake is LOUD. VERY LOUD.

Second thought I had was that in fact it felt quite "normal" riding it around.

Third, and the least surprising, was the fact that I was not able to do anything else with the bike other than riding around like one would ride a normal bike. Tried to see how hard it was for me to get the front wheel up in the air. Very hard indeed. I guess I could actually do it, but not in a controlled way, so each time I tried I was only able to have it up a couple of inches or so, for a split second.

 

 

Finally the banjo bolts came in yesterday afternoon. Wrong type for the MT4, the fit the MT. So MT caliper it is.

Today had all the time to finalize the front brake so went for it.

While getting things together for the new bleed I noticed I in fact had half of a Jagwire pro hose in celeste left over from my Budnitz urban bike. I guess the brand new one I ordered will go in my next build, whatever that will be (most like a gravel bike- the only bike I still do not have and yet need, as a friend is trying to get me into the local cyclocross scene. Last Saturday actually went to check out a local race, it was a blast. But I digress).

Pulled the leaking red hose out, the celeste one went in, then bled everything. No leaks this time. Done. Took a vetry long time for such a simple task, but done.

Took the bike out on the driveway and tested the front brake. The lever is firm so very little if any air in there. But being a 2 pot caliper, it's not as crisp as I would like. The bike rolls a bit before coming to a stop. Not much, but it does. By comparison, the MT7 I have on the full suspension mountain bile will throw you over the handlebar if you grab a handful.

Maybe that's how I will like it- only time will tell.

For now I will get post mount adapters and larger, 203 mm rotors and see how that changes things.

 

 

So bike finally complete. For the most part. Might make a minor change or two down the road.

 

Might change pedals (the ones I have on were conveniently laying around after changing to clipless on a mountain bike) if I keep riding it in winter. Metal pedals can get very cold and I have been told by people riding in cold weather that swapping to plastic pedals kept feet decidedly warmer.

If I continue to be unhappy with the front brake I will swap it for a Magura MT7.i

Would be nice to get a brake booster.

And at some point when Tarty finally have them in stock, will probably build a 22" front wheel just for shits and giggles. If I don't like it I will go back to the 20" I already have.

 

 

But now I can start getting used to it and trying to learn the most basics of trials.

I have a feeling that by comparison, building the bike, as long as it took, will turn out to be the easy part.

But I'm excited about it.

 

In fact, after front brake was done, I took the bike out to the local state forest (where most if not all my learning adventure will take place) for the first time.

For a while I finished the last stretch of the freewheel "breaking in" process that I started on my driveway- just rode along the main trail for a while, pedaling and freewheeling. Once I got bored I turned back.

Then I started thinking about the main purpose of the bike- trials.

I really did not know where to start.

Started slowing down and inch forward using the pedal kick, and put some conscious effort into exploring the limits of the brakes especially the front one (was wondering if I could use it to get the rear wheel off the ground: no, not by itself- some weight shifting to the front will need to happen but did not want to go there for now).

Tried again to get the front wheel up in the air, just as hard as back in the driveway a few days ago.

By then it was getting dark so called it a day.

Next time I will go I will try to make a plan of attack.

Short time goals, etc.

I might even start a new thread, documenting my progress (or lack thereof).

 

But for now, this is it.

I had a lot of fun building this bike. Looking forward to have even more fun on it.

 

Thank you to all of you for every single piece of advice and helpful information- it all made this project a lot more enjoyable that it would have been if I tried to figure out this new world all on my own!

 

I am closing this thread with a bunch of pictures of the finished bike, out in front of the house, on a wet autumn day.

 

Cheers!

 

 

Edited October 5, 2022 by thousandwords

[Mark W]

Good to see it up and running finally  

Spending some time bedding in the front disc/pads should improve performance. Just pour some cold, clean water over the caliper and rotor, and ride around on flat ground pulsing the brake on and off. At first you'll have no bite at all, but it will gradually come through. Once it's started drying out, pour a little more water over it and repeat the process. If you do this a few times you'll feel the brake start to develop more and more bite. You can give the rotor a wipe down with some clean paper towel if you like. 

Until they're fully bedded in (the braking surface of the rotor should have a mirror finish once it's bedded in fully) you won't get the full power of the brake, so it's worth spending a bit of time doing. 

Enjoy the arm pump