Moving a Schlumpf Drive...

[[XAP]Bob]

I've bitten the bullet and hired the Schlumpf cutting tool for a bit.

So I'm going to shift the drive from the Rapto (which will need a replacement) to the ICE Sprint.
Will get me 17.5-127 GI gearing (4-30mph @ 80RPM) alongside the motor...

Anyone fitted them before?


The Rapto will then need a new chainset, I haven't decided whether to go ST or use the spare hollowtechII I have in the drawer.
Need to work out chainring sizes though (and a sane shifter - the heel shift was great)

[squeaker]

Ran 53/38 on 150s on mine (I like to spin, but don't bother pedaling down steep hills) using a Shimano 105 mech and SRAM X5 twist shifter.
HTH

[[XAP]Bob]

The other obvious question....

Fitting an external BB onto a BB shell machined for a Schlumpf drive.
The facing is there to ensure that the bearings are square - The Shclumpf has a bevel on that edge, but the outside of the bevel is likely to still be square anyway - I can't see that there would be any pressure on that face, so is there a reason not to fit an External BB onto a shell which has had an HSD removed?

[[XAP]Bob]

Well.. that was fun.

Three hours it took us.

Going carefully obviously.

Removing the HSD was Ok, needed a tiny socket because I didn't have the schlumpf protector tool for crank extraction (the spine that does the gear changing would get mashed if it wasn't protected), but no major dramas. Who decided on a 1.5mm Allen key for the buttons? Bends and twists....
There was still a good amount of flatt bb outside the bevelled area, so the HT2 BB (with metal spacers) went on easily.

Cutting the bevel was nerve wracking, but we Got them dome (39.5-40mm wide at the widest part, 40.5 is dangerous!)

Then the drive went on easily. 100ftlb of torque needs a car mechanics torque wrench, but was OK...

Specialist tools are a pita though.

Target 3-30 mph (60-90rpm) on the trike and 4-40 (same) on the raptobike - but that needs a new wheel.

Got to decide whether to keep the CS-RK3 (3spd SA & 9spd cassette) rear wheel or to sell it as well....

[breakwellmz]

Just by chance i put the Quest tv channel on the other day and the Schlumpf drive hub was featured in a `How is it made` program.It`s used by unicyclists it seems.

[[XAP]Bob]

Yes, they do a low backlash version, as well as short BBs and heavy duty ones. Many for handcycles...

[[XAP]Bob]

Well, having now done a few commutes on the new system...


It's doing very well on my trike, moving them is actually rather easy - just make sure you line it up right wrt the lubrication port (I managed to rotate that behind the boom first time).

Also the noise I had suspected was the Schlumpf, and then thought was the idler on the Rapto was at least partly the rear mech. I can hear the jockey wheels spinning up when I am in the higher gear range - 75 teeth at 90rpm is 600+rpm for the poor little things...

[[XAP]Bob]

Update.

I've actually moved it back (although having just had the trike serviced I'm wondering whether I was right (I think I was)).

The issue I had on the trike was that the very high gears were simply higher than I need on a commute - the lower 'high' gears were fine for most of the journey, but pulling off meant dropping to the higher 'low' gears.

So I was doing too much double shifting - I'm not using basically just the outer of the original triple. I max out at about 30mph, but at a somewhat higher cadence than I would have done, not that big a deal.

Whilst I was in the states I tried some short (142mm) cranks, and decided to buy a pair of shorter cranks for the Schlumpf (155mm). I also picked up a package containing the 'schlumpf installation and maintenance' toolset. Basically everything other than the BB chamfer tool.

So I have got the Schlumpf back on the raptobike, and properly adjusted (which is a bonus, somehow the bearings had been significantly tightened...)
New pedals as well (since I pulled the clips off the previous pedals). Short test ride was fine. Now I need to solder up the lights and take it out for some real riding.