Crank Shortening

Price-list and order-form
Crank length

I can shorten most solid aluminium cranks by reshaping their ends and then drilling, tapping and facing new pedal holes. Special jigs are used to ensure the accuracy of this work.

By how much?	Cranks can be shortened by 20mm or more. See Crank length for advice on choosing the length of your cranks.
Options	Cranks can be threaded left or right, for normal (9/16") or junior (1/2") pedals.
Tandem cranks	Cranks can also be reverse-threaded for tandem cross-over drives.
Extra holes	Extra holes give you a choice of pedal positions, but they also weaken your cranks, so I will only add them if you indemnify me against breakage. Why not use Pulse Crank Shorteners instead?

shorten

Cranks suitable for shortening

They must be made from solid aluminium and should be as chunky as possible. Most old cranks are suitable but some of the modern ones aren't - see below.

I'm often asked to recommend the best cranks to purchase for shortening, but this is difficult as designs change frequently according to the whims of fashion. However most current Truvativ cranks seem to be ok - I'll add more recommendations here as and when I can. (Last updated 18 March 2010).

	Not possible...

		Some cranks can't be shortened (use Pulse Crank Shorteners instead) :
			hollow cranks steel cranks carbon cranks very narrow cranks (narrower than 25mm at the new pedal position) deeply fluted cranks (leaving less than 10mm material thickness)

Your guarantee

If I have doubts about the suitability of your cranks, I will contact you before proceeding.
Special jigs are used to ensure that every new pedal hole is true to the bottom-bracket axle (even if your crank is bent!)

But please note

Don't ask me to work on your cranks unless you accept my terms and conditions.

The alternative: Pulse Crank Shorteners

These attach to your cranks to provide a choice of three new pedal positions. They can also be removed and do not alter your cranks in any way. Click here for further information.

Prices

Crank shortening		GB pounds

1 crank		£ 25.00
1 pair of cranks		£ 40.00
plus each extra hole (see above)		£ 7.50
plus extra if chainrings attached (see below)		£ 5.00

Post and packing	UK	£ 4.00
	Europe	£ 8.00
	World	£ 15.00

How to send your cranks

Remove the chainrings and clean your cranks (otherwise please add £ 5.00 to your payment).
Attach a label to each crank with your name on it.
Include clear instructions, your address and a daytime phone number or email address.
Enclose a cheque or postal-order payable to 'Chris Bell', arrange a bank transfer (bank details on request), or request a PayPal invoice to be emailed to you.
Wrap everything carefully and send it by a secure service (eg. Royal Mail 'Signed-For').
If requesting extra pedal holes, add the following note to your instructions, date and sign it: 'I understand that extra holes will weaken my cranks. I indemnify Highpath Engineering against crank breakage'.

Timescale and Delivery

You should allow 4 weeks for the work to be completed. There may be delays at certain times of the year (eg. busy periods and holidays). Please contact Chris if you need more information. Click here for full delivery information.

Crank length

It is important to use the correct length of crank to ensure that your legs can work efficiently. You risk damaging your knees if you habitually use cranks which are too long, especially as you get older. 170mm cranks, which most cycle manufacturers fit as standard to most bicycles, are unsuitable for anyone shorter than the average European adult male and are therefore too long for most people in the World!

Normally fit adult riders should use cranks which measure about 20% of their effective leg length, rounded to the nearest 5mm, whereas growing children can safely increase this figure to 22%. This length goes all the way to your hip joint and cannot be measured directly. Ask a friend to measure your height twice - first when you are standing upright against a wall, without shoes on, and second when you are sitting squarely against it. Then subtract one measurement from the other one, as shown below.

The following table shows recommended crank lengths for normally fit riders on upright bicycles, based on the 20% to 22% range. Even shorter cranks may be required by disabled riders with restricted knee movement and by users of faired racing recumbents (due to space restrictions). Additionally, riders with very long legs may need shorter cranks on standard upright bicycles, to prevent their toes hitting the front wheel or their pedals hitting the ground when cornering.

	leg :	50	52.5	55	57.5	60	62.5	65	67.5	70	72.5	75	77.5	80	82.5	85	87.5	90	92.5
	child : adult :	110 100	115 105	120 110	125 115	130 120	140 125	145 130	150 135	155 140	160 145	160 150	165 155	170 160	175 165	175 170	180 175	180 180	185 185

Note that, not only do riders with shorter legs need shorter cranks, they also need smaller chainrings and will probably ride slower than riders with long legs and long cranks (rear cranks on tandems are an exception to this). Never try to achieve a higher gear ratio by using longer cranks.

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Chris Bell, HIGHPATH ENGINEERING
Cornant, Cribyn, Lampeter, Ceredigion, SA48 7QW, Wales, UK