Thorn Crank Shorteners

I recommend this product

I fitted the variable crank arm to left crank to allow me to utilise static bike during recovery from knee replacement. Allowed me to have pedal less than half way up the crank and gradually adjust as the knee flexed more each day.

I recommend this product

I found this product very well made, if a bit “chunky “ having said that it does inspire confidence in its durability. The fit was very good as was all the threaded parts cleanly made.

I recommend this product

My partner needed to shorten her cranks on our tandem following hip and knee surgery. We looked at a variety of shorteners but these are by far the best. Easy to fit and super easy to adjust.

The range of lengths available with no incremental steps is amazing, you could fit a small child and adjust as they grew.

We have them.different lengths and often stop on the road for fine tuning as her joint mobility is variable, you just need an 8mm hex key.

I recommend this product

I recently had a replacement knee which means that I can’t bend my leg enough to pedal a full circle with a normal crank. These crank shortness provided the ideal answer. They are very well made and easy to fit (I only fitted one) and as my knee gets more flexible I can just adjust the shortner to gradually provide a larger turning circle. I’m very pleased with them as they’ve allowed me to get back on my bike after my operation. For anyone who has a problem similar to mine I can thoroughly recommend them.

I recommend this product

My partner has knee replacements and was struggling with knee flexion. She rides in the recumbent stoker seat of our Hase Pino. We had short (150mm) drilled cranks but she needed something shorter.
There are other crank adjusters but these are the only ones with infinitely variable length, the others give a couple of alternative holes some distance apart and nothing in between.
These were easy to fit, cleverly designed to fit a wide variety of cranks and very east to adjust. We were able to make very fine adjustment to the crank length and boom extension (think saddle height on an upright bike) and reach a perfect compromise.
But once we are on the road we'll be able to continue to fine tune them (just needs a 6mm hex key) and the exercise will probably help improve flexion so we can gradually adjust the length to suit. Absolutely brilliant and she is thrilled.
Perfect for adapting a tandem or bike to a growing child as well as helping people with short legs or joint problems.

I recommend this product

Looking for crank shorteners several times and I looked at these more then once and past them over as being too flimsy, I was wrong these shorteners are very robust !
Easily fitted to bike and very pleased with them.
Fast service and had a quick delivery.

I recommend this product

I used this on a tandem to adjust the stoker cranks- they have been very effective. Fitting is very easy and only requires a couple of basic tools. The only issue is that they do increase Q factor by a fair amount (maybe 12mm or so each side), however the same problem arises no matter which crank shortener you use- so these are still a clear winner.

I recommend this product

Well designed and well engineered. Good finish and fully adjustable to any crank length within the published parameters. I looked at several different designs and these are by far the best design I found and very simple to fit.

I recommend this product

flexibel einstellbar, gut zu montieren, stabile Ausführung

I recommend this product

Bought this to enable my daughter who is disabled to reach the pedals on her trike. Easy to fit and adjust (had to make a spacer to convert M10 to M8 using an M8 threaded rod joiner to fit the crank lower bracket fixing for her trike) Works a treat

I recommend this product

Bought for partner following knee replacement as bend now restricted. Well made, easy to fit. A plus is that it length is continuously adjustable. Not just for tandems.

I recommend this product

Good simple well engineered product. Not cheap, but it will be a small volume product. Ideal when a child is too big for kiddy cranks, but too small to ride an unaltered bike.

I recommend this product

Quality product, easy to fit, works great. My children, 7 and 9 years old, can now fully enjoy our tandem rides.

I recommend this product

Precise machined with a nice finish. Needed longer M8 (i recommend 12.9) bolts and some extra washers to fit the shorteners to Simano cranks with large offset. Easy to assemble and supposedly indestructible.

I recommend this product

Easy install and setup. Make 11 year old a better stoker. Some concern about Q angle but did not present a problem. Replaced pedal blocks that made it difficult to mount. Very adjustable, but limited future options on a 170 crank, Can also adjust for leg length difference.

Nach einer Keiminfektion im Knie kann ich nach Prothesenwechsel
mein Knie nur noch ca 90 Grad abbiegen. Durch die Kurbelverkürzung
kann ich wieder Fahrradfahren. Danke und schöne Grüße.

I recommend this product

These crank shorteners arrived so quickly & in 10 minutes I had them fitted to my Halfords Carrerra Kraken 18" MTB. I had a new right knee in January & could not peddle around fully with the ball of my foot on the peddle. Once the shortners were on & adjusted I had full circular peddling ability. I have just reyturned from a week riding in the Lakedistrict & it was fantastic. I am only 70 as well GREAT THANKS TO SJS CYCLES

I recommend this product

Good to get on the bike so my daughter can get stoking on the way to school! promptly delivered and easy to fit, happy days!

I recommend this product

Yes a beautiful quality product that enables my 6 year old daughter to be stoker on our Viking tandem.
The man in my bike shop fitted them and commented that the bolts were only just long enough. I was surprised as I thought our tandem to be standard. If I find they come loose I will buy the longer bolts.

I recommend this product

got these to allow me to get back on my bike soonest. easy to fit, well made and simple instructions. i would have liked to buy one side only as opposed to the pair so will probably sell the other side on ebay (anyone interested?)

I recommend this product

One word, brilliant!
My 7 year old son was rapidly outgrowing the tag a long used for the school run on a daily basis. The crank shorteners mean that he can act as stoker on my tandem and grow into it as his legs get longer.
It is a quality product,beautifully machined and with everything included to fit them.