Gravel bike project

[Grant Fondo]

Someone somewhere must have heard me moaning about parcels as I had a delivery this afternoon from Chain Reaction, a lovely purple bottom bracket

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My printed parts finished overnight so I cleaned them up and cured them this morning. They fit nicely so thats another job ticked off

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I glimpsed a break in the rain so decided to take her ouside for the first time and take some photos - I really like the way this build is shaping up

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That 3D printing is awesome

 

[ColinJ]

I DO like your work! (Not just on this project; on all of them.)

 

[AndyRM]

Shaping up to be another belter, chapeau!

 

[avsd]

The Mint Sauce sheep head decal on the head looks well. Breaks up the purple.

 

[JhnBssll]

My eBay 'bargain' RX4 calipers arrived earlier in the week. They were advertised as non-functional and priced to suit so I'd already ordered new pistons and seals which arrived yesterday. The seller suggested the kept seizing and after many bleeds he'd given up on them and gone back to SRAM red calipers - being an avid RX4 fan I thought this was unusual so was interested to take a look at them

Here they are out of the box...

There are a few marks and scratches but nothing significant, so far so good... The pistons are chipped and seized as described by the seller so no surprises here...

Then I turned them over and noticed a minor problem...

The eagle eyed amongst you might have noticed the two small letters laser etched under the '4'... The SR on the rear caliper (bottom of the picture) denotes SRAM but the SH on the front caliper above it denotes Shimano SRAM use dot fluid and shimano use mineral oil so the donut has been using the wrong fluid in the front caliper. No doubt the seals are all swollen and perished which goes a long way to explaining the poor function... Still, I'd ordered new seals so I can just rebuild it, right? Not quite The early RX4 calipers have different diameter pistons between shimano and SRAM version, as well as different size pads. Fortunately the more recent RX4+ calipers share a common piston size so all the necessary seals are available for Dot fluid so I've just ordered the bits I'm missing and will start stripping the calipers down shortly for a clean and rebuild. Nothing is ever easy Here's my pile of rebuild bits so far...

Also to arrive today were the cranks and some gear cable. I've popped the cranks on for a test fit, all looking good so I'll tighten them up later and pop the pedals on 😄

 

[JhnBssll]

I've just finished stripping and cleaning the calipers The pistons were nicely seized in both - the sides with the piston caps were easy to pop out but the other 4 needed some persuasion I ended up carefully drilling a 2.5mm hole all the way through the centre of each piston and tapping an M3 thread. This then allowed me to wind in an M3 screw until it bottomed out at the end of the cylinder then carefully keep winding to pull the piston out.

The red seals in the picture below are meant for mineral oil and, as predicted, they're feeling pretty sorry for themselves after being filled with dot fluid. They were swollen, cracked and deformed so its really no wonder the caliper wasn't working

Before long I had both calipers stripped...

Time for a bath 😊

They spent about 30 minutes in the ultrasonic cleaner in the end - longer than I had anticipated as I forgot about them for a while Suffice to say they were nice and shiny when they came out, so I rinsed them out and popped them on a radiator to dry out 😊

I'm waiting on the additional seals and pistons for the front caliper before I can rebuild but I'm in no hurry, plenty of other bits to be getting on with

 

[JhnBssll]

The GX rear mech finally arrived today so I was able to fit the Ratio Technology cable fin. I can't fit it to the bike yet because I noticed the gear hanged was bent and ordered a new one which is yet to arrive, but I've taken a photo of the two cable fins next to each other to demonstrate the difference. The original, longer fin is on the right and the new Ratio Technology fin is fitted:

I also realised I had enough new bits to rebuild the rear caliper, and make a start on the front...

Won't be long until I can assemble it all and go for a ride now The saddle has also arrive, I'll try and pop that on later along with the pedals 😊

 

[Grant Fondo]

The GX rear mech finally arrived today so I was able to fit the Ratio Technology cable fin. I can't fit it to the bike yet because I noticed the gear hanged was bent and ordered a new one which is yet to arrive, but I've taken a photo of the two cable fins next to each other to demonstrate the difference. The original, longer fin is on the right and the new Ratio Technology fin is fitted:

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I also realised I had enough new bits to rebuild the rear caliper, and make a start on the front...

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Won't be long until I can assemble it all and go for a ride now The saddle has also arrive, I'll try and pop that on later along with the pedals 😊

Hey! Just watch that lovely paint job

 

[chriswoody]

The GX rear mech finally arrived today so I was able to fit the Ratio Technology cable fin. I can't fit it to the bike yet because I noticed the gear hanged was bent and ordered a new one which is yet to arrive, but I've taken a photo of the two cable fins next to each other to demonstrate the difference. The original, longer fin is on the right and the new Ratio Technology fin is fitted:

That's the bit that frustrates me the most, in order to make a SRAM MTB derailleur play nicely with drop bar shifters, you just need to swap the cable fin from a Rival 1 Derailleur, which is essentially all the Ratio Parts one is. Yet SRAM refuses to make the part available as a spare part, or even offer a special wide range Derailleur for gravel bikes, It really makes no sense to me.

Back on topic though, it's coming together lovely though. The serviceability of those Hope brakes is one of the reasons I love them, can't believe you had a mixed pair though, that's quite special.

 

[JhnBssll]

Getting there now 😄

I've put the bent hanger back on to allow me to cable up the mech and check its all working, which fortunately it is 😄 I couldn't resist spending a few more quid on the XX1 rainbow chain as I thought it would match the colourscheme nicely

So the remaining jobs are:

- Tidy up the dropper cable and tighten slightly
- Finish rebuilding the front caliper when the new pistons and seals arrive
- Replace the rear brake hose
- Fit, bleed and adjust the calipers
- Replace the mech hanger when the new one arrives then tweak the indexing
- Wrap the bars
- Change the tyres
- Ride it like I stole it

That's the bit that frustrates me the most, in order to make a SRAM MTB derailleur play nicely with drop bar shifters, you just need to swap the cable fin from a Rival 1 Derailleur, which is essentially all the Ratio Parts one is.

As it happens I have a spare Rival1 rear mech if you'd like the cable fin off it

 

[AndyRM]

Very, very cool!

 

[JhnBssll]

I couldnt resist bolting the rear caliper on to see what it looks like...

 

[tom73]

Getting there now 😄

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I've put the bent hanger back on to allow me to cable up the mech and check its all working, which fortunately it is 😄 I couldn't resist spending a few more quid on the XX1 rainbow chain as I thought it would match the colourscheme nicely

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So the remaining jobs are:

- Tidy up the dropper cable and tighten slightly
- Finish rebuilding the front caliper when the new pistons and seals arrive
- Replace the rear brake hose
- Fit, bleed and adjust the calipers
- Replace the mech hanger when the new one arrives then tweak the indexing
- Wrap the bars
- Change the tyres
- Ride it like I stole it



As it happens I have a spare Rival1 rear mech if you'd like the cable fin off it

Complete with new cycling headwear I see

 

[chriswoody]

As it happens I have a spare Rival1 rear mech if you'd like the cable fin off it

That's the problem, I have a Rival 1 Mech already on the bike and I need a GX Eagle Mech. Unfortunately all the second hand GX Eagle mechs are just as pricey as the brand new ones.

That does look quite impressive though, hard to believe it's an old Boardman.

 

[Grant Fondo]

I couldnt resist bolting the rear caliper on to see what it looks like...

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Fantastic! Don't forget to take it back to Halfords for some expert fine-tuning.