Fork spring dimensions

[baroquenride]

Anyone know the fork spring dimensions? I don't want to take my springs out to check as I'm still riding it lately and hoping someone knows the length and diameter.

[DAVID THOMPSON]

is it the newer 4 stroke rt125
dave

[baroquenride]

125SM

[Puffs]

Gabel 125SM,SX.jpg (18.85 KiB) Viewed 419 times

For changing the pre-load, just use a different spacer #5. Use same on either side.

Obviously that will adjust the ride height & handling.

[baroquenride]

Changing preload does absolutely nothing for the spring rate which is what needs to change for me. I'm just hoping someone knows before I take one of the springs out myself. I'm hoping to cheat and reuse one of the several sets of springs I have stored.

I had some time to pull the spring out and it measured 32mm x 55cm long with a progressive section on one end about 2" long. Nope, I don't have a spring I can substitute.

[Puffs]

I see. But knowing only length & diameter is insufficient to calculate the spring rate, for that you need more info:

Spring rate formula.jpg (11.85 KiB) Viewed 419 times

(There are spring rate calculators on the web.)

If you feel you need another spring rate for this bike, for whatever reason, the spring you desire might be difficult to find. Either have it custom made, or play with:
- preload (length of spacer 5),
- damping (if there is no adjustment: oil viscosity),
- changing the oil level (higher for a stronger progressive spring action),
- you could even consider additional air support (via a channel through caps 3).

[baroquenride]

I'm very familiar with all that, but might be helpful for someone else in the future.

[Puffs]

But of course you are. You asked, I just tried to help.

Out of interest: what problems do you have with the stock springs?

[baroquenride]

--The spring rate. I'm 230lbs out of the shower. The stock springs are probably meant for a 150lb rider. I'd have to measure them against a scale and yard stick to calculate the rate, which I could have done the other day when I pulled one out. Perhaps next week I'll check.

[Puffs]

Thanks, I suspected something like that, or bottoming-out @ hard braking. You might find more suitable springs from another bike at a breaker?

Otherwise still: a bit of extra spacer to increase preload, + bit higher oil level.

[baroquenride]

Yes, I'm considering cutting off the progressive end of the springs to increase the rate and using a longer spacer to match the length and add preload, however that still wouldn't give me the correct rate for my weight and riding ability and my thought is, "what's the point?" I'd rather leave it stock in case I someday sell it. This is a fantastic bike for a smaller person and it may someday get sold to someone smaller and lighter person than me who would appreciate the stock springs.

[DAVID THOMPSON]

i weighed 230 to 235 LB most of the time i have owned mine
and found it to be a delight to ride

dave

[Puffs]

Not trying to say anything about your ancestors, of either of you, but I'd guess the bike was primarily designed for its home market, and Germans are not commonly regarded as 'petite'. But indeed, the bike was probably aimed at young guys, which tend to be lighter than Helmut Kohl (6'4", 300+lbs).

Anyway, on replacing the narrow spaced part by a longer spacer: yes, that will increase the spring rate (see formula above), BUT: you'll ruin 2 otherwise perfectly fine stock springs, and if you cut off a spring (angle grinder) without first properly shaping the end (oxyacetylene torch) it will bend on load & grind onto the stanchion. Yes, "what's the point?" springs to mind (pun intended).
I'd just add an ½" spacer (nylon ring) on top of the existing ones, raise the oil level a bit, and then just enjoy the bike the way it is.

You can't always get everything exactly as you want it. Which is good, for it leaves things to be desired!