P-38 build

DIscuss anything relating to non-standard cycles and their equipment.
UpWrong
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Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

I've fitted the tyre and disc rotor to the new front wheel and installed the wheel into the fork. It needed a 1mm disk spacer to align the rotor between the caliper pads but looks good now. The rear is problemmatic. This an existing disk hub wheel which needed a bit of truing up first. I fitted a new 32-559 Panaracer Pasela PT and rotor but could not get the caliper alignment. It looks angled rather than just to one side. I recall having problems with the 700c wheel too, one bolt of the caliper bracket was not torqued down.

So I have ordered a BB7 brake since these have the conical concave spacers which allow for more general realignment. Having done that I realise I could perhaps use the spacers from a V-brake shoe similarly to angle the existing Tektro caliper. Doh!

EDIT: Looking at it, better to use a BB7 IS bracket, caliper bolts and concave spacers in order to get a secure caliper at the right height.

BTW, sat on the bike whilst holding it on the front brake and the seat height feels comfortably lower.
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

BB7 brake fitted. The caliper aligned on the 6th attempt. It sounds easy, squeeze brake lever and tighten caliper bolts but the inboard pad has to be in the right place to begin with, which isn't its position when it comes out of the box. It took me 5 attempts to find it.

The outboard pad adjuster conflicts with the rack leg. I'll need to undo and spring the leg in order to access the adjuster.

I realise now that the wheel swap has tilted the bike back 3mm, the front hub was lowered by 28.5mm whereas the rear was lowered by 31.5mm. The smaller front wheel decreases trail, tilting the bike back slackens the headtube which increases the trail. The amount of fork flop isn't noticeably altered.

I haven't yet shortened the seat stays, nor have I yet changed to shorter cranks, so the hip angle is the same. But the seat height is lower. I shall go for a potter and reacquaint myself with the bike.
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Back from a short jaunt to bed the back brake in down a steep hill. The steering is a bit lighter and quicker, but not alarmingly so. The bike is more manageable with the lower seat height. I felt more confident is slow tight turns. Next step is to lay the seat back. Hope the handlebars aren't then too high and/or block my vision. I can always cut down the riser more but it's not a reversible process.
UpWrong
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Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Everything is a compromise! I put the seat back and it changes the weight distribution and affects the handling. The front was lighter and it felt more like riding an upright folder or something, or maybe just more like other tail heavy SWBs. Still manageable. I had to rotate the bars to bring the grips closer. Visibility was still ok. However it became more awkward to reach the ground, making stop/starts in traffic more stressful. BUT, the hip angle was more open and I felt I could employ my leg muscles and back muscles better which was the main reason for switching to the smaller wheels.

So what now? I'm torn between riding it more like it is, or raising the seat halfway back to where it was (i.e. 75% laidback). Changing the seat angle is quite laborious so tempted to ride it more as it is, although the boom needs to come in a little I think. Another tricky adjustment because the torque setting has to be just so, 9 Nm I think, 8 wasn't enough to stop it slipping.
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

The front hub colour nicely matches the frame :D
IMG_20220723_181834_HDR-1024x1024.jpg
After taking this I rotated the bars back a little, and I have now brought the boom back in by 1/4 inch.

You can see that my head will now only be a short distance ahead of the rear axle. The stay-less front mudguard can come off easily if the weather is dry and I want to improve the aerodynamics a bit.

EDIT: the crank shortening service wasn't available so this is still with 160mm cranks. The cassette on the 26" rear wheel is 11-32, it was 11-34 on the 700c wheel. I'll take a link out if I keep it as 11-32.
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

I had a decent 15 mile ride this morning. No problems with stability when pushing 30 mph downhill. I was unlucky with traffic and riding into a moderate breeze on what should have been the faster sections of the course. The hip angle didn't feel closed anymore but stopping and starting was a bit tricky with the raised front edge of the seat. I think I shall raise the back of the seat by a cm on the stays. It's a question of finding that compromise position.
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

This is a never ending story. Another ride today. Happy with the seat recline and with reaching the ground. The seat stays have only about 1/2" extension from being fully laid back. Handling was good. BUT the riding position still feels a little too closed. So I do need shorter cranks. I'll probably steal them off the Paseo since it's impossible to buy 150mm triple cranks with a reasonable chainline in the UK. (Unless you know otherwise?) I can't swap the cranksets over because the Paseo is a 10 speed set up and the XD-2 cranks on the P-38 are 9-speed. The shortened Paseo cranks are TD-2s which are 10 speed compatible. I have a set of 165mm TD-2s which I can try on the Paseo in place of the 150mm ones. Conversely the Paseo hip angle feels a bit too open so the 165mm cranks might help :) .
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Tigerbiten
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Joined: 29 Jun 2009, 6:49am

Re: P-38 build

Post by Tigerbiten »

Are you after a good chainline or Q factor ??

As mentioned earlier, SJS Cycles do 104/64 triple cranks from 150mm upwards.
JIS Square Taper
110mm bracket required to get a 51mm chainline on middle ring.
107mm can be used if only using a single ring in the outer position.

Both SJS and Spa do 150mm length 110mm BCD doubles, but you'd need a Double to Triple Conversion Chainring.
I can find one in 130mm BCD but not 110mm BCD.

Possible more options from this page -> http://velovoice.blogspot.com/2014/11/c ... of-it.html

Luck .......... :D
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Tigerbiten wrote: 27 Jul 2022, 5:43am Are you after a good chainline or Q factor ??

As mentioned earlier, SJS Cycles do 104/64 triple cranks from 150mm upwards.
JIS Square Taper
110mm bracket required to get a 51mm chainline on middle ring.
107mm can be used if only using a single ring in the outer position.

Both SJS and Spa do 150mm length 110mm BCD doubles, but you'd need a Double to Triple Conversion Chainring.
I can find one in 130mm BCD but not 110mm BCD.

Possible more options from this page -> http://velovoice.blogspot.com/2014/11/c ... of-it.html

Luck .......... :D
I'm after a good chainline to the idler and a low Q-factor. I spent a long time looking at the SJS cranksets. I think there are mistakes in some of their descriptions. I'm sure they are all the same and that they are designed for a 54mm chainline with a 110mm bracket, which is what is required for a Rohloff hub. Thanks for the Velovoice link.
Jdsk
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Re: P-38 build

Post by Jdsk »

UpWrong wrote: 27 Jul 2022, 10:13am I spent a long time looking at the SJS cranksets. I think there are mistakes in some of their descriptions.
They are very good at answering questions, both in the public Q&As and by email.

Jonathan
UpWrong
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Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Jdsk wrote: 27 Jul 2022, 10:15am
UpWrong wrote: 27 Jul 2022, 10:13am I spent a long time looking at the SJS cranksets. I think there are mistakes in some of their descriptions.
They are very good at answering questions, both in the public Q&As and by email.

Jonathan
It looks like the same crankset with different ring options, and different staff have answered the question about chainline slightly inconsistenty but it's clear that the primary aim of the crankset is for Rohloff hubs with a 54mm chainline. It looks like I might be selling the Paseo anyway so I don't mind swapping cranks around.
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

I am setting some personal strava segment records incrementally on the P-38 so I don't appear to be slower with the smaller wheels. It actually feels harsher at the back with the 559 wheel and 32 mm tyre than the front with 349 wheel and 40 mm tyre. I'm definitely more relaxed in traffic with the lower seat height.

What I will say is the the faster yiou go on damaged country lanes, the bumpier the ride gets, Not rocket science of course!
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Oh dear, I'm getting chain jam and chain suck with the current XD-2 crankset. Oddly I also had chain jam with the same chanset when it was on my Spa Wayfarer and it was running different rings, a different chain and a different FD. Guess I really will have to pinch the TD-2 crankset off the Nazca now. That's currently set up as a 32-46 super compact double. I have considered using that on the P-38 stretching it to a 30-46 double with a 12-36 cassette. But that's a rather high bottom gear of gearing (20.4" to 93.8") expecially when the cranks are 150mm. The existing triple set up gives 18.4" to 98" and I'm not using all the derailleur capacity. The triple wins.
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Tigerbiten
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Joined: 29 Jun 2009, 6:49am

Re: P-38 build

Post by Tigerbiten »

If you want to run a sub-compact double then, I think, the best cassette to match it up with is the 11-42 SRAM 11 speed.
With that combo, setting the top gear at 100" it will give you 2 gears sub 20".
That's the same as a maximized triple.
A theoretical max range of 5.85x vs the 6x of a triple.

Luck ......... :D
UpWrong
Posts: 2409
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: P-38 build

Post by UpWrong »

Tigerbiten wrote: 31 Jul 2022, 8:30am If you want to run a sub-compact double then, I think, the best cassette to match it up with is the 11-42 SRAM 11 speed.
With that combo, setting the top gear at 100" it will give you 2 gears sub 20".
That's the same as a maximized triple.
A theoretical max range of 5.85x vs the 6x of a triple.

Luck ......... :D
Yes, I agree an 11 speed 11-42 cassette is the best option for a double, but that would mean changing all the transmission components to 11-speed. I have a custom 10 speed 13-42 cassette with the double on the Paseo which comes close. It just lacks the top end. I could move all the 10-speed stuff across from the Paseo to the P--38. One advantage is I could take the P-38 to BHPC races since it would have a chainguard.
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